MESSENGER MASCS UVVS
Calibrated and Derived Data Record
Software Interface Specification 

Version 5.7
April 11, 2017





Prepared by:

Noam Izenberg
Applied Physics Laboratory

Jennifer Ward
PDS Geosciences Node
Washington University



Document Review

This document and the archive it describes have been through PDS Peer Review 
and have been accepted into the PDS archive.

William McClintock, MESSENGER Cognizant Co-Investigator/MASCS, has reviewed 
and approved this document.

Noam Izenberg, MESSENGER MASCS Instrument Scientist, has reviewed and 
approved this document.

Lyle Huber, PDS Atmospheres Node Representative, has reviewed and approved 
this document.

Susan Ensor, MESSENGER Science Operations Center Lead, has reviewed and 
approved this document.



Document Change History

Revision Number
Revision Date
Author
Section 
Remarks

1.5
4/7/09
Start of revision history. Version submitted to PDS for Release 4.

1.6
1/8/10
J. Ward, GEO
5.3.4, Tables 3a & 3b, 6.3.2, Appendix B
1. Replaced sample PDS labels with new versions containing PRODUCT_VERSION_ID.
2. Added PRODUCT_VERSION_ID to  UHCINDEX.TAB and USCINDEX.TAB column lists.
3. Updated UVVSSCIC.FMT columns to match file delivered in PDS Release 5.
 
1.7
9/15/10
J. Ward, GEO
5.2, 5.3.4.1, 5.3.4.2, 6.1.2, 6.1.3, 6.1.4, 6.3.2, Appendix B
1. Updated to describe new macro-based files.
2. Updated data product naming convention.
3. Added EXTRAS directory tables.
4. Removed <HHHH> subdirectories from CDR directory structure.

1.8
12/6/10
J. Ward, GEO
6.3.1, 6.3.2, Appendix A, Appendix B
1. Corrected formula for MIDSTEP_TIME.
2. Appended statement to PACKET_SUBSECONDS description.

1.9
5/5/11
J. Ward, GEO
6.1.3, 6.1.4
Updated to reflect new data directory structure.

2.0
6/10/11
J. Ward, GEO
6.1.4
Updated EXTRAS directory contents.

2.1
6/14/11
S. Ensor, SOC
Document Review
Replaced signature page with Document Review information.

2.2
6/17/11
J. Ward, GEO
6.1.4
Renamed SUPERTABLE.XLS TO MASTER_CRUISE_TABLE.XLS.

2.3
1/24/12
N. Izenberg, MASCS;
J. Ward, GEO
2, Table 2, 6.1.4, 6.3.2, Appendix B
1. Added reference to calibration update document. 
2. Temperature and solar scattering correction added to EDR to CDR 
processing steps table.
3. Added new documents to DOCUMENT and EXTRAS directory contents.
4. Spare column in UVVSSCIC.FMT converted to PMT temperature.

2.4
3/26/12
W. McClintock, MASCS;
J. Ward, GEO
All
Converted to CDR/DDR Data Product SIS, adding new DDR data product. Draft 
version.

2.5
4/10/12
J. Ward, GEO
5.3.4.2, 6.3.1.2, Appendix B
Revised CDR sample label and format file.
2.6
4/13/12
W. McClintock, MASCS; J. Ward, GEO; R. Espiritu, ACT
Figures, Section 7
1. Added figures 2a-2c.
2. Deleted "UVVS position vectors in the inertial J2000 coordinate frame" 
figure.
3. Renumbered all figures.
4. Removed Section 7 Archive Release schedule.
5. Revised DDR index table columns.

2.7
4/20/12
N. Izenberg, MASCS; R. Vervack, MASCS
5.2.2, 5.3.4, 6.1.2, 6.1.3, 6.1.4, 6.3.2, Appendix C
1. Deleted DDR HDR file references (no DDR HDR file).
2. Revised DDR SCI file structure and description.
3. Renumbered sections/appendices.
4. Inserted new directory structure figure.

2.8
4/30/12
J. Ward, GEO
5.2.2, 5.3.4, 6.1.3, 6.1.4
Formatting and consistency edits.

2.9
5/3/12
J. Ward, GEO
Appendix C
Updated UVVSSCID.FMT.

3.0
5/11/12
A. Merkel, MASCS; J. Ward, GEO
5.3.4.3, 6.3.2.1, Appendix C
1. Format file edits.
2. Changed DDR file naming convention.

3.1
5/14/12
J. Ward, GEO
Appendix C
Fixed typo in UVVSSCID.FMT.

3.2
5/16/12
S. Ensor, SOC
2, 3, 4, 5.3.3, 5.5
Updated Applicable Document 4 name and references to it.  Referenced 
Applicable Document 4 for delivery schedule.

3.3
5/18/12
J. Ward, GEO
6.1.4, Figure 4, Tables 3a-3c
1. Edited catalog directory contents.
2. Minor edits to directory structure.
3. Removed length column from index table contents table.

3.4
5/30/12
J. Ward, GEO
5.2.1, 5.3.4
Minor typo.

3.5
7/17/12
J. Ward, GEO
6.1.4
EXTRAS directory contents.

3.6
12/13/12
J. Ward, GEO
6.1.4
DOCUMENT and EXTRAS directory contents.

3.7
4/22/13
P. Bedini, SOC, J. Ward, GEO
All
Editorial changes.

3.8
4/25/13
J. Ward, GEO
All
Added new surface reflectance and atmosphere surface density data products.  
Draft version.

3.9
6/5/13
N. Izenberg, MASCS
All
Added Surface DDR information.

4.0
6/13/13
J. Ward, GEO
All
Additional edits.

4.1
6/19/13
R. Vervack, MASCS, J. Ward, GEO
5.2.2.3, 5.3.4, 6.1.2, 6.3.4
Added Atmospheric Model DDR information.

4.2
10/10/13
J. Ward, GEO
6.3.2.2, Table 3c
DDR-DAP peer review revisions.

4.3
12/4/13 
J. Ward, GEO
2, 6.1.4
Added Applicable Document. Updated DOCUMENT and EXTRAS directory contents.

4.4
12/6/13
J. Ward, GEO
2, 6.1.4
Minor edit.

4.5
1/10/14
J. Ward, GEO
6.1.2, 6.1.4
Minor edits.

4.6
1/16/14
J. Ward, GEO
6.1.4
Minor typo.

4.7
2/18/14
J. Ward, GEO
5.2.2.3, 5.3.4.6, 6.1.4
1. Added Ca Chamberlain model document.
2. Updated Na atmospheric model sample label.

4.8
7/9/14
N. Izenberg
5.4.2, Various
MET/UT fixes, standardization between products, minor edits.

4.9
1/20/16
S. Ensor, SOC
All
Mission edits. Reflect use of DEM in final surface pointing parameters.

5.0
1/21/16
J. Ward, GEO
All
Additional minor edits.

5.1
1/27/16
J. Ward, GEO
6.1.4
Additional minor edits.

5.2
2/22/16
R. Vervack, MASCS, J. Ward, GEO
All
Additional edits from Vervack for final release.

5.3
9/1/16
R. Vervack, G. Holsclaw, MASCS, J. Ward, GEO
All
Added information for new data products: UVVS+VIRS Combined DDR, UVVS 
Atmosphere Summary DDR, and UVVS FUV Surface DDR.

5.4
1/23/17
J. Ward, GEO
Appendix L
Added Appendix L.

5.5
3/30/17
R. Vervack, MASCS, G. Holsclaw, MASCS, J. Ward, GEO
All
Various edits for PDS release 16.

5.6
4/7/17
A. Merkel, MASCS, J. Ward, GEO
5.2.2.3, 6.1.4
Additional minor edits.

5.7
4/11/17
J. Ward, GEO
6.1.4, 6.3.1, Appendix B
Additional minor edits.



Table of Contents

1.  Purpose and Scope of Document  
1.1  Purpose  
1.2  Scope  
2.  Applicable Documents  
3.  Relationships with other Interfaces  
4.  Roles and Responsibilities  
5.  Data Product Characteristics and Environment  
5.1  Overview of Instrument and UVVS Observation Types  
5.1.1  Instrument Description  
5.1.2  Description of UVVS Observation Types  
5.1.2.1  UVVSDaysideScan  
5.1.2.2  UVVSPolarScan  
5.1.2.3  UVVSExoScan  
5.1.2.4  UVVSExoStare  
5.1.2.5  UVVSExoNadir
5.1.2.6  UVVS360Roll  
5.1.2.7  UVVSPAARideAlong  
5.1.2.8  UVVSExoTargetObs  
5.1.2.9  UVVSLimbStare  
5.1.2.10  UVVSLimbOpp  
5.1.2.11  UVVSNightColumn  
5.1.2.12  UVVSNightShadow  
5.1.2.13  UVVSFIPSMPTangentRideAlong  
5.1.2.14  UVVSFIPSNightsideRideAlong  
5.1.2.15  UVVSFIPSZStareRideAlong  
5.1.2.16  UVVSFIPSPAOptRideAlong  
5.1.2.17  UVVSEPSEquatorRideAlong  
5.1.2.18  UVVSEPSPoleRideAlong  
5.1.2.19  UVVSDownlinkRideAlong  
5.1.2.20  UVVSStarCal  
5.1.2.21  UVVSSurfaceTarget  
5.1.2.22  UVVSGridPoint  
5.1.2.23  UVVSPhotometry  
5.1.2.24  UVVSSatSearchRideAlong  
5.1.2.25  UVVSVulcanoidRideAlong  
5.2  Data Product Overview  
5.2.1  Calibrated Data Records (CDRs)  
5.2.2  Derived Data Records (DDRs)  
5.2.2.1  MUV Surface DDRs  
5.2.2.2  FUV Surface DDRs  
5.2.2.3  Atmosphere DDRs  
5.2.2.4  Atmospheric Model DDRs  
5.3  Data Processing  
5.3.1  Data Processing Level  
5.3.2  Data Product Generation  
5.3.3  Data Flow  
5.3.4  Labeling and Identification  
5.3.4.1  Example PDS Label for the UVVS Science Header CDR  
5.3.4.2  Example PDS Label for the UVVS Science CDR  
5.3.4.3  Example PDS Label for the UVVS MUV Surface Header DDR  
5.3.4.4  Example PDS Label for the UVVS MUV Surface Science DDR  
5.3.4.5  Example PDS Label for the UVVS FUV Surface Header DDR  
5.3.4.6  Example PDS Label for the UVVS FUV Surface Science DDR  
5.3.4.7  Example PDS Label for the UVVS Atmosphere DDR  
5.3.4.8  Example PDS Label for the UVVS Atmosphere Summary DDR  
5.3.4.9  Example PDS Label for the UVVS Atmospheric Model DDR  
5.4  Standards Used in Generating Data Products  
5.4.1  PDS Standards  
5.4.2  Time Standards  
5.4.3  Coordinate Systems  
5.4.4  Data Storage Conventions  
5.5  Data Validation  
6.  Detailed Data Product Specifications  
6.1  Data Archive Structure and Organization  
6.1.1  Handling Errors  
6.1.2  File Naming Conventions  
6.1.3  Directory Structure and Contents for MASCS CDR/DDR/DAP Archive Volume
6.1.4  Directory Contents  
6.2  Data Format Description  
6.3  Label and Header Descriptions  
6.3.1  CDR Column Descriptions  
6.3.1.1  Fields in Science Header CDR Format File (UVVSHDRC.FMT)  
6.3.1.2  Fields in Science Data CDR Format File (UVVSSCIC.FMT)  
6.3.2  Surface DDR Column Descriptions  
6.3.2.1  Fields in Surface HDR DDR Format File (UVVSHDRD_SUR.FMT)  
6.3.2.2  Fields in MUV Surface SCI DDR Format File (UVVSSCID_SUR.FMT)  
6.3.2.3  Fields in FUV Surface SCI DDR Format File (UVVSSCID_FUV_SUR.FMT)  
6.3.3  Atmosphere DDR Column Descriptions  
6.3.2.1 Fields in Atmosphere DDR Format File (UVVSSCID.FMT)  
6.3.4  Atmosphere Summary DDR Column Descriptions (UVVSSUMD.FMT)  
6.3.5  Atmospheric Model DDR Column Descriptions  
7.  Appendices  
APPENDIX A- UVVSHDRC.FMT FILE  
APPENDIX B- UVVSSCIC.FMT FILE  
APPENDIX C- UVVSHDRD_SUR.FMT FILE  
APPENDIX D- UVVSSCID_SUR.FMT FILE  
APPENDIX E- UVVSSCID_FUV_SUR.FMT FILE  
APPENDIX F- UVVSSCID.FMT FILE  
APPENDIX G- UVVSSUMD.FMT FILE  
APPENDIX H- SPICE Kernel Files Used In Messenger Data Products  
APPENDIX I- CODMAC/NASA Definition of Processing Levels for Science Data Sets
APPENDIX J- ACRONYMS  
APPENDIX K- MASCS Instrument Overview  
APPENDIX L- MASCS Data Product Summary  



1. 
Purpose and Scope of Document

1.1 Purpose
This document provides users of the MESSENGER Ultraviolet and Visible 
Spectrometer (UVVS) data products with a detailed description of the 
instrument (Figure 1) and observation types (Figures 2a-2q), as well as 
Calibration Data Record (CDR) and Derived Data Record (DDR) generation and 
storage. The UVVS data products are deliverables to the Planetary Data 
System (PDS) and the scientific community that it supports. All data formats 
are compliant with PDS standards. In addition, this Software Interface 
Specification (SIS) documents the format and content of the MESSENGER MASCS 
CDR/DDR/DAP PDS archive volume. This document is both a CDR/DDR data product 
SIS and a CDR/DDR/DAP archive volume SIS.

Figure 1: MASCS Instrument, UVVS Subsystem.
See PDF version of document for figure.


1.2 Scope
This specification is useful to those who wish to understand the format and 
content of the UVVS CDR and DDR data products. Typically, these individuals 
include software engineers, data analysts, and planetary scientists. The SIS 
applies to CDR/DDR data products produced during the course of MESSENGER 
mission operations. Experiment Data Records (EDRs), the raw, uncalibrated 
data from MASCS UVVS, are addressed in the UVVS EDR SIS (Applicable 
Document 8).  EDR data products are archived in a separate PDS archive 
volume.



2. Applicable Documents
This SIS references the following documents:
1. MESSENGER Mercury: Surface, Space Environment, Geochemistry, Ranging; A 
mission to Orbit and Explore the Planet Mercury, Concept Study, March 1999. 
Document ID number FG632/ 99-0479.
2. Planetary Data System Archive Preparation Guide, NASA/JPL, August 29, 
2006, Version 1.1, JPL D-31224.
3. Planetary Data System Standards Reference, NASA/JPL, March 20, 2006, 
Version 3.7, JPL D-7669, Part-2.
4. MESSENGER Data Management and Archiving Plan. The Johns Hopkins 
University, APL. Document ID number 7384-9019.
5. [PLR] Appendix 7 to the discovery program Plan; Program Level Requirement 
for the MESSENGER Discovery project; June 20, 2001. 
6. MASCS Users Guide. Laboratory for Atmospheric and Space Physics, 
University of Colorado. Document ID number 20580-T5-5103.
7. Instrument Calibration Report. Mercury Atmospheric and Surface 
Composition Spectrometer (MASCS) on the Mercury: Surface, Space 
Environment, Geochemistry, Ranging (MESSENGER) Mission. LASP/CU Document 
Number 20580-T6-7915.
8. MESSENGER MASCS/UVVS EDR SIS: APL doc no. SIE-06-044 D.
9. MASCS Instrument Paper: W. E. McClintock and M. R. Lankton (2007) Space 
Sci. Rev. 131, 481-522.
10. MASCS Calibration Release Notes: W. E. McClintock and G. M. Holsclaw. 
APL document ID number: TSSD-19929.
11. UVVS Calibration Changes for PDS Delivery 7: Aimee Merkel, Ron Vervack, 
Noam Izenberg and the MASCS Team, APL Doc. No. SRE-02-12.
12. MESSENGER MASCS UVVS Calibration Update - PDS 11: Aimee Merkel and the 
MASCS Team, APL Doc. No. SRE-02-13, December 5, 2013.



3. Relationships with other Interfaces
The UVVS data products are stored on hard disk and in an SQL (Structured 
Query Language) relational database for rapid mission access during mission 
operations. The data products are electronically transferred to the PDS 
Geosciences and Atmospheres Nodes according to the delivery schedule in the 
MESSENGER Data Management and Archiving Plan [Applicable Document 4]. The 
UVVS and VIRS CDRs, DDRs, and DAPs contain some data that are useful in 
cross-comparison, therefore both the UVVS and VIRS CDRs/DDRs/DAPs are 
grouped together in the MASCS CDR/DDR/DAP archive volume stored at both PDS 
nodes.



4. Roles and Responsibilities
The roles and responsibilities of the instrument teams, Applied Physics 
Laboratory (APL), Applied Coherent Technology Corporation (ACT), and the PDS 
are defined in the MESSENGER Data Management and Archiving Plan [Applicable 
Document 4].



5. Data Product Characteristics and Environment

5.1  Overview of Instrument and UVVS Observation Types
5.1.1 Instrument Description
The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) was 
comprised of a small Cassegrain telescope with a 257-mm effective focal 
length and a 50-mm aperture that simultaneously fed both an UltraViolet and 
Visible Spectrometer (UVVS) and a Visible and InfraRed Spectrograph (VIRS). 
MASCS investigated Mercury's exosphere by measuring altitude profiles of 
known species as well as searching for previously undetected species. MASCS 
investigated the mineralogical composition of the surface of Mercury by 
obtaining maps of surface reflectance spectra on spatial scales of 5 km.

UVVS was a scanning grating, Ebert-Fastie monochromator with a focal length 
of 125 mm and equipped with three photomultiplier tube detectors 
(see Table 1). The three detectors covered the wavelength ranges of the far 
ultraviolet (115-190 nm), middle ultraviolet (160-320 nm), and visible 
(250-600 nm) with an average spectral resolution of 0.6 nm. The UVVS 
detector helped determine the global composition and spatial structure of 
Mercury's exosphere by measuring emission from known species (H, Na, and Ca) 
and from newly discovered species (Mg, Al, Mn, and Ca+). In addition to 
determining the composition and structure of the exosphere, these confirmed 
detections provide the basis for determining exospheric processes, studying 
the relationship between surface and exospheric composition, and studying 
surface-exosphere-magnetosphere interactions. Searches were made for 
numerous additional predicted species (e.g. S, C, Si, Fe, OH, and Mg+). 
Observations were also acquired that covered emissions from O, which may or 
may not have been detected by Mariner 10, and K, which is known from 
ground-based observations but which was difficult for UVVS given that the 
strongest resonance line was outside the UVVS wavelength range. These 
searches are still undergoing analysis and will provide stringent upper 
limits even if no detections are found through detailed analysis.

VIRS was a fixed concave grating spectrograph with a 210-mm focal length 
(see Table 1). A beam splitter simultaneously dispersed the spectrum onto 
two solid-state array detectors: a 512-element silicon photodiode array, 
with a sensitivity to visible wavelengths (300-1050 nm), and a 256-element 
indium-gallium-arsenide photodiode array, to measure near-infrared 
wavelengths (850-1450 nm). It was optimized to measure visible and 
near-infrared surface reflectance, and VIRS obtained data with a resolution 
of 5 nm. Together, the VIRS and UVVS detectors measured surface reflectance 
at middle ultraviolet to visible to near-infrared wavelengths to search for 
ferrous-bearing minerals, Fe-Ti bearing phases, and ferrous iron. These 
measurements were made with a spatial resolution of 5 km or better. The VIRS 
data products are described in a separate VIRS data product SIS. The UVVS 
data products are described below.

Table 1: MASCS Instrument Overview.
See PDF version of document for table.

Please see Applicable Document 9 and Appendix K for additional details about 
the MASCS instrument.

5.1.2 Description of UVVS Observation Types
The UVVS data were acquired during a number of different observational 
sequences that are representative of the geometry of the observation and/or 
the particular science goal.  The following subsections describe each 
observation type.  The observation type for each individual measurement is 
indicated in column 52 of the UVVS CDRs.  There may be multiple observation 
types within a given CDR as several different observational scenarios can be 
spanned during the timeframe of a single macro execution.

5.1.2.1 UVVSDaysideScan
These were radial limb scans on the dayside. They generally spanned local 
times from dawn to dusk, but there were certain orbital geometries that 
allowed for observations only at dawn and dusk. There are three general 
cases for these scans that are illustrated in Figure 2a, and an example set 
of limb scans is shown in Figure 2b. In the final two Mercury years of the 
mission, there was also a mode that allowed these limb scans to cluster in 
smaller sets centered on a fixed local time on either the dayside or the 
nightside, despite the observation type name.

Figure 2a. This schematic illustrates the three general implementation cases 
for the dayside limb scans.  See the text for a discussion of the individual 
cases.
See PDF version of document for figure.

Figure 2b.  Illustration of a typical set of dayside limb scans.  In this 
and all similar figures that follow, the UVVS observations are represented 
by colored lines that run from the spacecraft orbit (represented by the red 
line at the start of each observational line) to the point where the line of 
sight is tangent to the radial line from Mercury's center (i.e., the tangent 
point).  Blue lines of sight represent less emission and red lines of sight 
represent more emission.  At the tangent point, the projected UVVS slit size 
is plotted.  The axes representations are as follows: blue = dawn, 
red = dusk, white = rotational (north pole), yellow = Sun direction.  The 
surface of Mercury is properly shaded to represent day and night, and the 
shadow of the planet is also shown.

The nominal seven-scan scenario with full local-time coverage is shown at 
the left in Figure 2a. The maximum altitude of each scan was fixed at 4000 
km, or at whatever maximum altitude was achievable within spacecraft 
pointing constraints. The scans took 9 minutes each. The numbers indicate 
the order in which the scans occurred (note that the order is often reversed 
depending on the orbital configuration and the direction the spacecraft is 
moving in orbit), the back-and-forth step-like nature across the planet 
being necessary to keep the particular local times within the allowed 
pointing window as the spacecraft moved in its orbit. This nominal 
seven-scan scenario covers the majority of the limb scans.

The thirteen-scan scenario (middle panel) covers some cases from early in 
the orbital phase (mostly Mercury years 1-5) and occurred when spacecraft 
pointing constraints did not allow for higher altitudes to be reached. To 
offset the lower altitude ranges (up to 2500 km maximum) the number of local 
times was increased. The time per scan in this case was reduced to 4 minutes 
per scan.

The four-scan scenario (right panel) occurred when full local-time coverage 
was not possible within the spacecraft pointing constraints. Instead, four 
scans were conducted, two at dawn and two at dusk, to study the important 
dawn-dusk asymmetries. These scans could reach 4000 km altitude maximum and 
take 9 minutes each.

In all cases, A and B indicate a particular macro.  A and B may be the same, 
but having different macros on the interleaved scans allowed for multiple 
species to be observed in a given sequence.  A and B may also indicate a 
change in the maximum altitude, with the A (or B) scans having a higher 
maximum altitude relative to the B (or A) scans.  This option was employed 
in various ways throughout the orbital phase to provide a mix of spatial 
resolutions during any given sequence.  The most common combination was A 
scans with maximum altitude of 4000 km and B scans with maximum altitude of 
2500 km.

It should be noted that some sets of observations are not, in fact, limb 
scans despite being labeled that way. These usually occurred when the limb 
scan window overlapped with either a downlink track or a lengthy non-UVVS 
observation such that the resulting limb scan set could not be completed in 
time. These scans generally initiated too late and drifted across local 
times because they ran into the SKI (Sun-avoidance constraint) limits. 
These "limb scans" should be filtered out of any analysis if true limb scans 
are expected. They tend to be characterized by abrupt changes in the 
altitude and/or local time scanning and can be filtered by searching those 
fields.

5.1.2.2 UVVSPolarScan
These were back-and-forth scans across the terminator over the polar 
regions. Nominally they occurred in sets of four (two north, two south), but 
sometimes parts of a set were lost due to a variety of circumstances. The 
northern scans were not very altitude-scan-like in their behavior owing to 
the spacecraft coming up over the north pole from the equator very fast. The 
southern scans were more like a normal altitude scan. If the spacecraft was 
inbound toward Mercury, the scan started at the highest altitude and moved 
down in altitude. If the spacecraft was outbound, the scan started at the 
lowest altitude and moved up in altitude. This was done to maximize the 
spatial resolution at the lowest altitudes. Be aware that toward the end of 
the extended mission and the beginning of the second extended mission, the 
original polar scan algorithm failed to keep some of the northern scans off 
of the planet, with the last instances of these before the problem was 
corrected actually falling completely on the planet. Users are advised to 
always check in all observations that the slit is completely off of the 
planet.  An example set of polar scans is shown in Figure 2c.

Figure 2c.  Illustration of a typical set of polar scans.  The left panel 
shows the zig-zag motion of the UVVS line of sight back and forth across the 
terminator for a southern polar scan, whereas the right panel shows how the 
northern polar scans were not well-confined to the northern pole as 
discussed in the text.
See PDF version of document for figure.

5.1.2.3 UVVSExoScan
These were back-and-forth sweeping scans that are generally referred to as 
"tail sweeps" even though they occur on both the nightside and dayside of 
the planet (although the vast majority is on the nightside). The scans may 
have actually swept across the planet at times, so care must be exercised to 
separate lines of sight completely in the exosphere from those that 
intersect the surface (as well as the rare case of a slit partially on and 
off the surface). All ExoScans were conducted with the line of sight 
perpendicular to the Sun-Mercury line.  The geometry of these scans is 
illustrated in Figure 2d, and an example set of ExoScans is shown in Figure 
2e.

Figure 2d. Schematic of two end-member examples of the exosphere mapping 
scans (tail sweeps). The left two illustrations show the 
noon-midnight/nightside apoapse case and the right two illustrations show 
the dawn-dusk/dawn side apoapse case.  As indicated in the illustrations, 
the exosphere mapping scans proceeded by rocking the spacecraft back and 
forth about the line from the spacecraft to the Sun-Mercury line. The angle 
of the rocking was adjustable, generally smaller near apoapse, and the 
resulting observational sequence was a series of "fans" stacked one after 
the other.
See PDF version of document for figure.
 
Figure 2e.  Illustration of a typical set of ExoScans.  The left panel shows 
a view from above the planet's north pole and shows how the back-and-forth 
scans progressed as the spacecraft moved from the far tail region toward the 
planet.  The right panel shows the fan-like nature of the scans and how they 
sampled inside and outside of the shadow region of the planet.
See PDF version of document for figure.

5.1.2.4 UVVSExoStare
During the primary mission, these were the default replacement for ExoScans 
when there wasn't enough time to do such a scan.  The ExoScan scheduling 
algorithm required that complete scans be made (i.e., no partial scans), so 
if there wasn't enough time in the ExoScan window to complete the scan 
fully, an ExoStare was scheduled instead. During these observations, the 
line of sight was perpendicular to and tracked the Sun-Mercury line at all 
times (this was the so-called "nominal" pointing mode). They often occurred 
in combination with LimbOpps (as an alternating series of ExoStares and 
LimbOpps; see UVVSLimbOpps below) because the most common occurrence was 
when UVVS was either riding along with a series of MDIS images or the 
spacecraft was "pausing" at the nominal position during a switch from one 
pointed observation to another. During the extended missions, these were the 
default replacement for ExoScans only when the ExoNadir observation (see 
UVVSExoNadir below) would place the line of sight on the planet or when both 
ExoStares and ExoNadirs would point at the planet.  ExoStares are similar 
enough to ExoNadirs that no separate figure is shown for this type.

5.1.2.5 UVVSExoNadir
In order to increase the time the exosphere was probed close to the planet, 
this mode was created as the default replacement for ExoScans in the 
extended mission and beyond. Rather than nominal pointing as done for 
ExoStares, these were observations in which the spacecraft was turned to 
point the UVVS line of sight as close to nadir as possible while still 
keeping the line of sight off of the planet and not violating the SKI 
restrictions, the goal being greater sampling at lower altitudes. Compared 
to the nominal pointing of ExoStares, the ExoNadirs always looked at lower 
tangent altitudes. These were still interleaved with LimbOpps in the 
schedule much of the time because of changes in the driver for G&C (UVVS 
versus MDIS); however, in those cases, both observations were in a 
nadir-pointing mode, so there is a distinction in name only. It should be 
kept in mind that not all LimbOpps were nadir-pointing, however, just the 
ones that occurred under the ExoNadir/LimbOpp combination (and not even all 
of those LimbOpps were nadir-pointing as LimbOpps were always something of a 
catch-all).  A typical example of an ExoNadir is shown in Figure 2f.

Figure 2f.  Illustration of a typical ExoNadir observation.  The UVVS line 
of sight drifted slowly toward or away from the planet with a slight tilt 
that kept the tangent point as close to the planet as possible while not 
going onto the surface or violating the SKI restrictions.  ExoStares are 
similar but the line of sight was perpendicular to the Sun-Mercury line and 
not tilted toward the planet.  These appear similarly on both the dayside 
and the nightside.

5.1.2.6 UVVS360Roll
These were 360 deg. rolls of the spacecraft that occurred on the nightside 
as close to the Sun-Mercury line as possible. The goal was to have these 
occur while the spacecraft was fully in shadow so as to provide a view of 
the exosphere in which dawn-looking lines of sight could be separated from 
the dusk-, north-, and south-looking directions. They were an attempt to 
repeat the flyby roll observations on a regular basis.

During the second extended mission and beyond, FIPS instituted a series of 
spacecraft rolls of their own.  Because these FIPS rolls mostly paralleled 
the UVVS dedicated rolls, UVVS piggybacked on these observations and the 
same UVVS360Roll label was used for these FIPS ride-alongs. The only 
difference between the two is that the FIPS rolls started at a different 
part of the orbit than the traditional UVVS rolls, which sometimes had the 
benefit that the FIPS rolls made it through two complete rotations 
(i.e., 720 deg.).  A typical roll observation is shown in Figure 2g.

Figure 2g.  Illustration of a typical roll observation.  The line of sight 
representations in this figure are odd-looking only because the line is 
plotted from the spacecraft to the tangent point, and at some point in the 
roll, the distance between the two reaches a minimum.  The primary purpose 
of this figure is to show that the rolls probed all directions relative to 
the Sun-Mercury line while the spacecraft was in the tail/shadow region of 
Mercury.
See PDF version of document for figure.

5.1.2.7 UVVSPAARideAlong
These observations started in the extended mission as ride-alongs during the 
hot seasons when the spacecraft attitude had to be adjusted to protect the 
phased-array antenna (PAA) from getting too hot. During the second extended 
mission and beyond, this label was also applied to dedicated, low-altitude 
UVVS observations over mid to high northern latitudes because this 
orientation provided a known compromise between low tangent altitudes and a 
thermally safe attitude for the spacecraft.  The look direction was more or 
less always toward dusk, and the tangent altitude generally swept from a few
hundred kilometers down to a few tens of kilometers before sweeping back up 
(i.e., a parabola-like trace in tangent altitude space).  Note that at 
times the line of sight did sweep onto the planet's surface, both dayside 
and nightside, so care must be exercised with these.  A typical PAA 
ride-along is shown in Figure 2h.
 
Figure 2h.  Illustration of a PAA ride-along.  The left panel shows how 
these progressed over the dayside of the planet, with the look direction 
always being to the dusk direction.  The right panel shows that these 
observations generally probed low altitudes.
See PDF version of document for figure.

5.1.2.8 UVVSExoTargetObs
These were targeted exosphere observations during the second extended 
mission and beyond designed to observe localized enhancements over certain 
geologic features or other regions of the planet. The goal was to sweep over 
a feature at low tangent altitudes when the spacecraft was also at low 
altitudes. Unfortunately, difficulties in scheduling these observations due 
to the various spacecraft and instrument health and safety restrictions, 
coupled with the high speeds of the spacecraft at low altitudes near 
periapse, led to these observations being of limited utility. An example of 
three ExoTarget sequences is shown in Figure 2i.

Figure 2i.  Illustration of three ExoTarget sequences.  These observations 
were of short duration and focused on geologic targets of interest to search 
for mini-exospheres.  The nearly constant color in each sequence shows that 
these observations were primarily measuring a constant background exosphere 
or, more likely, were overwhelmed by light scattered from the surface.
See PDF version of document for figure.

5.1.2.9 UVVSLimbStare
These were observations in which the UVVS line of sight was kept as close to 
the limb as possible for long periods of time. The target altitude was 
200 km, but spacecraft/instrument constraints (for other instruments) often 
resulted in the target altitude not being achieved, and sometimes the 
longer-duration LimbStares continued to high, non-fixed tangent altitudes 
once the SKI limits were reached and the spacecraft moved to high altitudes. 
Typical examples of LimbStares on a single orbit are shown in Figure 2j.

Figure 2j.  Illustration of several LimbStares in a single orbit.  These 
occured anywhere around the planet, day or night, and they did not always 
achieve the target altitude of 200 km.  Away from low altitudes, they tended 
to provide a random sampling of the exosphere.
See PDF version of document for figure.

5.1.2.10 UVVSLimbOpp
These were catch-all ride-alongs during observations by other instruments or 
during spacecraft slews. They occurred randomly in both space and time. 
Although intended to represent limb opportunities, the label was often 
misapplied to other types of observation and the line of sight often 
intersected the planet. These intersections occurred on both the nightside 
and the dayside. The general rule-of-thumb with these is: pay attention to 
where the UVVS line of sight was pointed.  Typical examples of several 
LimbOpps on a single orbit are shown in Figure 2k.

Figure 2k.  Illustration of several LimbOpps on a single orbit.  LimbOpps 
probed in any direction, day or night, and were generally the ride-alongs on 
slews between one observation type and another.  In this case, there are 
LimbOpps connecting ExoScans together and a LimbOpp (near the north pole) 
that connects nightside observations to a dayside sequence for the MDIS 
imager.

5.1.2.11 UVVSNightColumn
These were ride-alongs during observations by other instruments. Although 
intended to be observations when the UVVS line of sight intersected the 
nightside of the planet AND the spacecraft was not in shadow, they were not 
always identified properly. Sometimes, the UVVS line of sight did not 
intersect the nightside of the planet, and other times when it did the 
observation was labeled as something else.  These labels should be used as a 
guideline only and cannot be fully trusted.  A typical NightColumn 
observation is shown in Figure 2l.

Figure 2l.  Illustration of a typical NightColumn observation.  These 
generally probed the region between the spacecraft and the nightside 
planetary surface.
See PDF version of document for figure.

5.1.2.12 UVVSNightShadow
These were ride-alongs during observations by other instruments. Although 
intended to be observations when the UVVS line of sight intersected the 
nightside of the planet AND the spacecraft was in shadow, like the 
NightColumn observations, they were also not always identified properly. The 
line of sight may not have intersected the nightside of the planet or the 
spacecraft may not have been in shadow.  These labels should be used as a 
guideline only and cannot be fully trusted.  NightShadows are similar enough 
to NightColumn observations that no separate figure is shown.

5.1.2.13 UVVSFIPSMPTangentRideAlong
These were ride-along observations during one of the FIPS pointed 
observations implemented during the extended mission and beyond. They 
occurred when FIPS was attempting to view tangent to the magnetopause to 
capture incoming solar wind ions. These generally involved observations when 
the spacecraft was at high altitudes south of the magnetic equator, and the 
UVVS line of sight was usually looking away from the planet toward deep 
space; however, there were instances where these occurred closer to the 
planet (generally near noon-midnight orbits). They occurred on both the 
dayside and nightside of the planet.  A typical FIPSMPTangent observation is 
shown in Figure 2m.

Figure 2m.  Illustration of a typical FIPSMPTangent ride-along.  These 
generally occurred when the spacecraft was far from the planet in the Sun 
direction, with the UVVS line of sight pointed into deep space.
See PDF version of document for figure.

5.1.2.14 UVVSFIPSNightsideRideAlong
These were ride-along observations during one of the FIPS pointed 
observations implemented during the extended mission only (phased out in the 
second extended mission and beyond). They occurred when FIPS was trying to 
"see down the tail". The name "nightside" was chosen because they always 
occurred on the nightside. These generally involved observations when the 
spacecraft was north of the magnetic equator, and the UVVS line of sight 
rotated through a partial roll, often looking away from the planet but 
sometimes towards it.  These are similar enough to the FIPSZStares and 
FIPSPAOpts (see below) that no separate figure is provided.

5.1.2.15 UVVSFIPSZStareRideAlong
These were ride-along observations during one of the FIPS pointed 
observations implemented during the second extended mission and beyond. 
These were designed to execute in pairs, with the FIPS FOV centered along 
the +Z (magnetic) direction on one orbit and the -Z (magnetic) direction on 
the following orbit. For UVVS, this pointed the line of sight north of dusk 
on the first orbit and south of dawn on the following one, with a slight 
angle in the tailward direction in both cases. Because the orientation was 
fixed, these provided north-south cuts through the exosphere in dusk and 
dawn directions on back-to-back orbits.  A typical example of a set of 
FIPSZStares is shown in Figure 2n.

Figure 2n.  Illustration of a typical set of FIPSZStares ride-alongs.  These 
observations on back-to-back orbits provided north-south slices through the 
tail region of the exosphere, with a look direction toward the dusk on one 
orbit and toward the dawn on the other.  There was a slight tilt away from 
the planet in these observations.
See PDF version of document for figure.

5.1.2.16 UVVSFIPSPAOptRideAlong
These were ride-along observations during one of the FIPS pointed 
observations implemented during the second extended mission. These were 
designed to execute in pairs, with the FIPS FOV looking "up" on one orbit 
and "down" on the following orbit to give FIPS the best chance to observe 
the ion pitch-angle distributions. For UVVS, this pointed the line of 
slightly farther north of dusk on the first orbit than the 
FIPSZStareRideAlongs and slightly farther south of dawn on the following 
one. In this case there was a slight angle of the UVVS line of sight toward 
the dayside direction. Because the orientation was fixed, these provided 
north-south cuts through the exosphere in dusk and dawn directions on 
back-to-back orbits. A typical example of a set of FIPSPAOpts is shown in 
Figure 2o.

Figure 2o.  Illustration of a typical set of FIPSPAOpt ride-alongs.  These 
observations on back-to-back orbits provided north-south slices through the 
tail region of the exosphere, with a look direction toward the dusk on one 
orbit and toward the dawn on the other.  There was a slight tilt toward the 
planet in these observations.
See PDF version of document for figure.

5.1.2.17 UVVSEPSEquatorRideAlong
These were ride-along observations during one of the EPS pointed 
observations implemented during the extended mission and beyond. These were 
supposed to occur when EPS was near the magnetic equator, hence the naming 
convention. In practice, these were not always that close to the magnetic 
equator. The UVVS line of sight often rotated through a partial roll during 
these observations, with the general look direction tending to be away from 
the planet. Observations closer to the planet swept through a larger angle 
than the ones that occurred farther from the planet.  A typical example is 
shown in Figure 2p.

Figure 2p.  Illustration of a typical EPSEquator ride-along.  These short 
observations occurred at various places in the nightside exosphere, and 
usually involved the UVVS line of sight looking in a particular direction 
with a slight roll at times.
See PDF version of document for figure.

5.1.2.18 UVVSEPSPoleRideAlong
These were ride-along observations during one of the EPS pointed 
observations implemented during the extended mission and beyond. These were 
supposed to occur when EPS was near the magnetic pole, hence the naming 
convention. In practice, NONE of these were scheduled during the extended 
mission, but they became the EPS observation of choice during the second 
extended mission and beyond when the spacecraft was in the "low-altitude" 
phase (i.e., when spacecraft altitudes were <350 km). They generally had the 
UVVS line of sight pointed straight down at the planet's surface, crossing 
dayside and/or nightside depending on the MTA range. These are similar 
enough to EPSEquator ride-alongs that no separate figure is shown.

5.1.2.19 UVVSDownlinkRideAlong
These were ride-along observations during downlink. The UVVS line of sight 
was almost always pointed inertially in a fixed position, but sometimes the 
beginning or end of a downlink observation may include the slew to the 
downlink orientation. These came in two flavors: UVVS line of sight pointed 
toward the planet (usually good) and UVVS line of sight pointed away from 
the planet (often not very useful). The particular orientation depended on 
the Earth-Mercury configuration.  A typical example of a downlink ride-along 
is shown in Figure 2q.

Figure 2q.  Illustration of a typical downlink observation.  The direction 
of the UVVS line of sight was inertially fixed during these observations, so 
they provided slices through the exosphere in a fixed geometry.  The look 
directions depended on the Earth-antenna orientation but were mostly in the 
north-south direction.
See PDF version of document for figure.

5.1.2.20 UVVSStarCal
These were the stellar calibrations. They occurred every so often but were 
more common toward the end of the mission when the goal was to track the 
possible degradation of the instrument due to aging and increased thermal 
heating.  No figure is provided for these are they are not useful 
measurements of the surface or exosphere.

5.1.2.21 UVVSSurfaceTarget
These were UVVS observations of specific surface geologic regions. For these 
the UVVS line of sight was pointed AT the surface, so these are reflectance 
measurements.  No figure is provided for these as they are self-explanatory.

5.1.2.22 UVVSGridPoint
These were UVVS observations of specific surface points laid out in a 
regular grid pattern. For these the UVVS line of sight was pointed AT the 
surface, so these are reflectance measurements. No figure is provided for 
these as they are self-explanatory.

5.1.2.23 UVVSPhotometry
These were UVVS observations of specific surface regions for the purpose of 
establishing the photometric correction. For these the UVVS line of sight 
was pointed AT the surface, so these are reflectance measurements. No figure 
is provided for these as they are self-explanatory.

5.1.2.24 UVVSSatSearchRideAlong
These were ride-alongs with MDIS satellite search observations.  They could 
be pointed in any direction, including at the planet's surface if MDIS was 
using its pivot (but rarely was that the case), but the majority of these 
pointed into deep space.  No figure is provided for these but they were 
similar to the MPTangent ride-alongs shown in Figure 2m.

5.1.2.25 UVVSVulcanoidRideAlong
These were ride-alongs with MDIS Vulcanoid search observations.  They could 
be pointed in any direction, including the planet's surface if MDIS was 
using its pivot (but rarely was that the case), but the majority of these 
pointed into deep space.  No figure is provided for these but they were 
similar to the MPTangent ride-alongs shown in Figure 2m.


5.2 Data Product Overview
Please see Appendix L for a summary table of all MASCS data products.

5.2.1 Calibrated Data Records (CDRs)
The UVVS CDRs consist of calibrated data derived from MASCS UVVS EDRs. The 
Science EDRs are the raw data records used to derive emission and 
reflectance data used for scientific analysis. The Science EDRs contain raw 
counts of the UVVS photomultiplier tubes (PMT) at the commanded step of the 
UVVS grating, which correspond to a specific wavelength of light. Wavelength 
range and sensitivity of each PMT at each grating step vary, as documented 
in the MASCS Calibration Report, MASCS_CAL_RPT.PDF, provided in the DOCUMENT 
directory. Before the science data can be used for scientific analysis, the 
count rates in the EDRs must be converted to physical units and the data 
must be transformed into meaningful physical reference systems. This 
conversion yields calibrated data that are stored in CDRs. 

Table 2a lists the general processing steps from the EDR to the CDR level, 
along with the corresponding CDR table column names and numbers. The *.FMT 
files and their columns are fully described in section 6.3. The algorithms 
and tables used to convert raw, uncalibrated data to calibrated radiance at 
the sensor can be found in the CALIB and DOCUMENT directories of this 
archive volume.  Additional, non-standard corrections have been applied to 
some of the CDR data, for example, to account for unexpected grating 
offsets. These corrections are detailed in the file 
UVVS_PROCESSING_UPDATES_PDS16.PDF, located in the DOCUMENT directory. 
Information on the relevant time periods for these corrections may be found 
in UVVS_CDR_DS.CAT, located in the CATALOG directory.

Table 2a: UVVS EDR to CDR to Surface DDR Processing Steps.
See PDF version of document for table.

The UVVS CDR data product contains all the data from one observation set. An 
observation set is defined in three ways. 1) Before adoption of macro-based 
commanding on the spacecraft, one observation set contains all the CCSDS 
(Consultative Committee for Space Data Systems) packets generated by one 
photomultiplier tube in a given hour of operation. UVVS produces one CCSDS 
packet per scan of the instrument grating (one scan may have repeated passes 
and/or a zigzag across a defined number of steps). 2) After macro-based 
commanding of the instrument commenced, an observation set consists of the 
all scans and packets produced by a single macro call. The exception to this 
is case 3) for very long executions of high-data rate macros that produce 
hundreds of megabytes of calibrated data. These "fat" macros are subdivided 
into several hour chunks. A variable number of CDR products are generated 
each day depending on the UVVS observation plan. Macros were used to acquire 
all science data during the Mercury flybys and orbital phase of the mission.

One observation set is associated with two CDR data products: a science 
header table (HDR), showing the instrument command parameters for a given 
observation, and a science data table (SCI), showing counts, derived science 
data, and pointing information for each step of an observation. The CDRs are 
in binary table format, and each is described by a detached PDS label. The 
label files define the start and end time of the observation, product 
creation time, etc.  The label points to an associated format file that 
defines the fields of the binary table contained within the data file. 

The UVVS macro-based science header (HDR) CDR (case 2) contains engineering 
data that does not change over the entire packet. It has N records, where N 
is the same number as in the corresponding EDR, and there is 1 record per 
packet. Thus, there is a 1-1 correspondence between the science header CDR 
and the corresponding EDR.  The UVVS macro-based science (SCI) CDR contains 
per step data: 1 record = 1 step.  The file contains N * f(N) records, where 
N is the number of records in the corresponding EDR and f(N) is a function 
of how many steps are extracted from a given packet in the EDR. Thus, the 
records f(N) in the macro science CDR correspond to record N in the macro 
science header CDR, which corresponds to record N in the EDR.

There are three EDR data products produced by the UVVS instrument, one for 
each detector (FUV, MUV, VIS). The detectors are also referred to as the 
Photomultiplier Tube detectors (FUV PMT, MUV PMT, VIS PMT). These are 
identified in the EDR PDS label as the "UVVSFUV," "UVVSMUV," and "UVVSVIS" 
standard data products, respectively. There is also a MASCS housekeeping EDR 
data product generated by the MASCS instrument. This is identified in the 
PDS label as the "MASCSHK" standard data product. The housekeeping EDR is 
defined in both the UVVS and the VIRS EDR SISs. UVVS EDR and associated 
housekeeping data are input into the UVVS calibration pipeline to derive 
Calibrated Data Records (CDRs).

The CDR archive consists of 6 standard data products, 2 for each detector 
(FUV, MUV, VIS). These are identified as "UVVSCFUVHDR," "UVVSCFUVSCI," 
"UVVSCMUVHDR," "UVVSCMUVSCI," "UVVSCVISHDR," and "UVVSCVISSCI" CDRs.

There are three types of data stored in each data file: "raw" counts 
(RAW_STEP_DATA; SCI table column 39), count rates (SCI table columns 40-44), 
and calibrated radiances (STEP_RADIANCE; _KR & _W, 
SCI table columns 46 & 47, respectively).  Please see the table column 
definitions in section 6.3 for detailed descriptions of these columns.

5.2.2 Derived Data Records (DDRs)

5.2.2.1 MUV Surface DDRs
For the UVVS MUV surface DDR data products, one DDR contains all the 
derived reflectance data from one MUV surface observation. Only targeted 
surface observations acquired during Mercury orbit were processed to a DDR 
(i.e., flyby measurements are excluded).  Thus, there are only 4596 total 
UVVS DDRs.  The first step is to bin the CDR spectral radiance (L) to 2 nm 
intervals in the wavelength range 210-300 nm.  Next, this is divided by the 
expected spectral irradiance (Esun), equivalently binned, from a Lambertian 
surface normally illuminated by the Sun:

See PDF version of document for equation.

We use the measured solar irradiance from the SORCE-SOLSTICE instrument 
[McClintock et al, 2005], averaged over its first year of operation 
(starting in May 2003), and scaled in magnitude to the Mercury orbital 
distance at the time of each observation.  The derived radiance is known as 
the "radiance factor" or "I/F", and is contained in the field IOF_BIN_DATA.  
An estimate of the uncertainty is contained in the field IOF_BIN_NOISE_DATA. 
A photometric normalization procedure, described in Izenberg et al (2014), 
is used to convert the spectral reflectance to a common photometric geometry 
(i=45, e=45, a=90 deg.); this is contained in the field PHOTOM_IOF_BIN_DATA 
and the associated uncertainty in PHOTOM_IOF_BIN_NOISE_DATA.
 
There are two types of MUV surface observations, with macro identifiers 48 
and 49; both use a grating step of 1 and the surface slit position, and both 
have a minimum wavelength of 172.20 nm.  They differ by the total number of 
steps and thus the maximum wavelength, with macro 48 at 378.34 nm and macro 
49 at 320.62 nm.  Because the MUV surface DDRs are restricted to the 
wavelength range 210-310 nm, these two types of observations result in 
equivalent data products.

One observation set is associated with two surface DDR data products: a 
science header table, containing the instrument command parameters for a 
given observation, and a science data table, containing counts, derived 
science data, and pointing information for each wavelength bin (~5 grating 
steps) of an observation.  The surface DDRs are in binary table format, and 
the science header and data tables are each described by a detached PDS 
label. The label points to an associated format file that defines the fields 
of the binary table contained within the data file.

Table 2a lists the processing steps from the EDR to the CDR and DDR levels, 
along with the corresponding CDR and DDR table column names and numbers. The 
*.FMT files and their columns are fully described in section 6.3. The 
algorithms and tables used to convert EDRs to CDRs and DDRs can be found in 
the CALIB and DOCUMENT directories of this archive volume.

Izenberg, N.R., Klima, R.L., Murchie, S.L., Blewett, D.T., Holsclaw, G.M., 
McClintock, W.E., Malaret, E., Mauceri, C., Vilas, F., Sprague, A.L., 
Helbert, J., Domingue, D.L., Head, J.W., Goudge, T.A., Solomon, S.C., 
Hibbitts, C.A., Dyar, M.D., 2014. The low-iron, reduced surface of Mercury 
as seen in spectral reflectance by MESSENGER. Icarus 228, 364-374. 
doi:10.1016/j.icarus.2013.10.023.

McClintock, W.E., Rottman, G.J., Woods, T.N., 2005. Solar-Stellar Irradiance 
Comparison Experiment II (SOLSTICE II): Instrument Concept and Design, in: 
Rottman, G., Woods, T., George, V. (Eds.), The Solar Radiation and Climate 
Experiment (SORCE). Springer New York, pp. 225-258.

5.2.2.2 FUV Surface DDRs
FUV surface DDRs are structured similarly to MUV DDRs. There are only a few 
solar atomic emissions that are bright enough to be observed in the FUV 
channel; therefore, we restrict FUV DDRs to surface observations that have 
used macro 63, typically used for atmospheric scans of hydrogen Lyman alpha 
(121.6 nm) and oxygen (130.4 nm).  For any single observation, there are two 
distinct scan ranges: a 31-step scan from 119.1 nm to 122.45 nm and a 
21-step scan from 129.24 nm to 131.46 nm.  Each of these two ranges consists 
of contiguous grating positions in 1-step increments.  A notable difference 
from the MUV DDRs is that these FUV observations use the long, atmospheric 
slit position in order to obtain sufficient signal. The measured radiance 
and the solar irradiance are integrated in the spectral ranges 
121.5 +/- 0.5 nm and 130.5 +/- 0.5 nm.  The reflectance (I/F) is otherwise 
calculated identically as that for the MUV DDRs, resulting in values at only 
these two wavelengths.  

The Sun is much more variable at FUV wavelengths than in the MUV 
[Rottman, 1999]. We use the daily-averaged solar spectral irradiance 
provided by SORCE-SOLSTICE [McClintock et al, 2005] and available from the 
LISIRD database (http://lasp.colorado.edu/lisird/).  The SORCE spacecraft 
operates in a low-Earth orbit (LEO) and, in general, views a different 
hemisphere of the Sun than that which contributes to the solar irradiance 
experienced at Mercury.  A temporal/spatial interpolation is required that 
produces an estimated solar spectral irradiance at any arbitrary time and 
position of Mercury.  There are a few periods of time when SOLSTICE was not 
operating nominally and did not produce data products.  In these cases, we 
used the Flare Irradiance Spectral Model (FISM), also available on LISIRD.  
In order to match the measurements of SOLSTICE, we smooth both datasets with 
a 60-day filter using the LOWESS algorithm.  The FISM time-series of the 
1-nm binned 121.5 nm and 130.5 nm flux was normalized to the low-frequency 
response measured by SOLSTICE.  Next, the contrast of the corrected FISM 
time-series was adjusted to match that of SOLSTICE; it was determined that a 
factor of 0.7 was required to minimize the error.  A composite time-series 
was then constructed with the SOLSTICE measurements and the corrected FISM 
fluxes to fill the gaps.  Compared to the MUV DDR surface data products, a 
new field (BIN_SOLAR_IRRADIANCE_W) was created to contain the solar 
irradiance used to calculate the reflectance.

McClintock, W.E., Rottman, G.J., Woods, T.N., 2005. Solar-Stellar Irradiance 
Comparison Experiment II (SOLSTICE II): Instrument Concept and Design, in: 
Rottman, G., Woods, T., George, V. (Eds.), The Solar Radiation and Climate 
Experiment (SORCE). Springer New York, pp. 225-258.

Rottman, G., 1999. Solar ultraviolet irradiance and its temporal variation. 
Journal of Atmospheric and Solar-Terrestrial Physics 61, 37-44. 
doi:10.1016/S1364-6826(98)00114-X.

The UVVS+VIRS Combined DDRs are described in a separate specification 
document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory 
of this volume.

5.2.2.3 Atmosphere DDRs
The UVVS Atmosphere Derived Data Records consist of time-ordered sequences 
of radiance values that are measured along lines of sight perpendicular to 
Mercury radius vectors.  The viewing direction for each measurement is 
provided by the latitude, longitude, and altitude of the spacecraft and the 
latitude, longitude, and altitude of the minimum ray (Figure 5a).  There are 
three general geometry-based classifications of Atmosphere DDRs and a series 
of orbit-level summary Atmosphere DDRs.

The first geometry-based classification is the dayside limb scans (LS), 
which are acquired as sets of limb altitude profiles at specific local 
times.  These are all of the observation type UVVSDaysideScan and are 
illustrated in Figures 2a and 2b.

The second geometry-based classification is the dayside and nightside limb 
drift profiles (LD), which are acquired in a more random fashion.  These 
drift observations were serendipitous exospheric limb profile measurements 
during ride-alongs with other instruments, and they can be composed of data 
from several of the defined observation types depending on the geometry of 
the given observation.  They occurred anywhere in the orbit as long as the 
UVVS line of sight observed off the planetary limb. As ride-along 
observations, the pointing was dictated by the other instruments; thus, the 
UVVS pointing may have varied during any given drift observation, and the 
altitudes covered ranged from as few as a hundred kilometers to as many as 
several thousand kilometers. They are an attempt to provide as many altitude 
profiles as possible in addition to the defined limb scans in the first DDR 
classification. The basic geometry of these is illustrated in Figure 2r.

Figure 2r. Schematic illustration of the geometry that is typical of the 
limb drift observations. 
See PDF version of document for figure.

The final geometry-based classification is the nightside tail sweeps (NS), 
which are simply the UVVSExoScans that occurred on the nightside of the 
planet.  These are illustrated in Figures 2d and 2e.

Each of these three geometry-classified Atmosphere DDR products is generated 
for the three major exosphere species that were regularly observed by the 
UVVS: sodium (Na), magnesium (Mg), and calcium (Ca).  The Mg data in the 
DDRs are observations of the emission line at 285.3 nm, the Ca data are 
observations of the emission line at 422.8 nm, and the Na data are 
observations of the doublet emission lines at 589.2 nm (D2) and 
589.8 nm (D1). All wavelengths are specified in vacuum. The total radiance 
calculated for Na pertains to the sum of the D1 and D2 lines, which overlap 
to some extent at the spectral resolution of the UVVS.

A single file for the geometry-classified Atmosphere DDRs contains all of 
the observations for a given species and geometry classification that were 
acquired during a single Mercury year. "Mercury year" is defined as the time 
to cover the full 360 degrees of Mercury's orbit around the Sun, with the 
starting point being at 0 degrees true anomaly. Because MESSENGER orbit 
insertion and the start of science data acquisition occurred at 73 degrees 
true anomaly, the first Mercury year only covered a range from 73 degrees to 
360 degrees. The final Mercury year was also a partial year, covering true 
anomalies from 0 to 64 degrees at mission end.

Table 2b summarizes the general processing of the geometry-classified 
Atmosphere DDR products.  They were assembled from the CDRs by filtering 
each species to identify the particular geometry classification and 
eliminating observations of marginal to no use (e.g., saturated spectra, 
spectra with the slit half on/half off the planet).  Each Atmosphere DDR 
product consists of time-ordered sequences of spectra (wavelength versus 
radiance value), total radiance (total column emission rate), and pointing 
information for each minimum ray altitude within the given Mercury year. 
Additional, non-standard corrections were applied to certain Mg and Ca data 
and are outlined in the UVVS_PROCESSING_UPDATES_PDS16.PDF file in the 
DOCUMENT directory.

The final Atmosphere DDR type is the orbit-level summary file. As opposed to 
the geometry-based classification Atmosphere DDRs described above, which 
group observations of a particular geometry together by Mercury year and 
species, these orbit-level summary Atmosphere DDRs are comprised of all 
the observations for a given species for a given orbit in a single 
Atmosphere DDR file.  There are thus a series of Atmosphere DDR files for 
every orbit during which science data for a given species were acquired.  
All observation types are included in these files, but as with the 
geometry-classified Atmosphere DDRs, some data are excluded (e.g., saturated 
spectra, spectra with the slit half on/half off the planet).  There are 
versions of these orbit-level summary files for Na, Ca, and Mg.  These 
orbit-level summary Atmosphere DDRs represent the most complete set of 
usable exospheric data on Na, Ca, and Mg.  The geometry-classified 
Atmosphere DDRs are simply subsets of the data in these orbit-level summary 
Atmosphere DDRs that have been broken out into specific observational 
geometries for ease of finding those specific geometries.  A typical 
orbits-worth of observations that may be contained in the orbit-level 
summary Atmosphere DDRs is shown in Figure 2s.

Figure 2s.  Illustration of the various observations that comprise a typical 
orbit of UVVS exospheric data as found in a single orbit-level summary 
Atmosphere DDR file.  There are DaysideScans, tail sweep ExoScans, and a 
variety of LimbOpps, ExoNadirs, and NightColumn observation types in this 
particular orbit.  Note that the colors of the UVVS lines of sight have been 
stretched to emphasize the variations in exospheric emission around the 
planet.
See PDF version of document for figure.

All of the various Atmosphere DDRs are in binary format and each is 
described by a detached PDS label.  The label files define the start and end 
time, creation date, etc.  The label points to an associated format file 
that defines the fields of the binary table contained within the data file. 
The UVVS Atmosphere DDR file contains pointing data and N records, where N 
is the number of sequential spectra recovered from the filtering process.

There are nine geometry-classified Atmosphere DDR standard data products 
produced from the CDRs, three for each species.  These are identified as 
"UVVSDNALS,"  "UVVSDNALD," and "UVVSDNANS" for sodium.  Names for Mg and Ca 
are produced by replacing 'NA' with 'MG' and 'CA', respectively.  There are 
two types of data stored in each science file: RADIANCE versus WAVELENGTH 
(spectra, table column 23) and TOTAL_RADIANCE in each observed emission line 
(total radiance measured at each altitude (pointing), table column 25).

There are three orbit-level summary Atmosphere DDR standard data products 
produced from the CDRs, one for each species.  These are identified as 
"UVVSDNASUM", "UVVSDCASUM", and "UVVSDMGSUM".  There are two types of data 
stored in each science file: RADIANCE versus WAVELENGTH (spectra, 
table column 22) and TOTAL_RADIANCE in each observed emission line (total 
radiance measured at each altitude (pointing), table column 24).

Table 2b: UVVS CDR to Atmosphere DDR Processing Steps.
See PDF version of document for table.

5.2.2.4 Atmospheric Model DDRs
The UVVS Atmospheric Model Derived Data Records consist of a series of model 
fits to data averaged over specific Mercury true anomalies and local times.  
These model fits, and the parameters provided in the DDRs, are described 
below.  The description is given for Na, but Ca and Mg are similarly fitted. 
For a full description of the Ca model, please see 
CALCIUM_CHAMBERLAIN_MODELS.PDF in the DOCUMENT directory.

It should be noted that these models are intended only as a first-order 
approximation of the average atmospheric state on the dayside using a 
well-known and accepted model (the Chamberlain model).  However, such models 
lack some of the relevant physics that are pertinent to the Mercury 
exosphere.  As such, they are excellent starting points for more detailed 
models but should not be interpreted as a true representation of the actual 
exosphere.  More detailed models are too complicated to provide in any 
meaningful way.

The model employed is adapted from the model developed by Chamberlain 
(1963).  The temperature and density of the dayside sodium exosphere were 
found by fitting the estimated column densities from individual limb scans. 
The fit applies only to the lower 700-1000 km of the exosphere, which is 
relatively cold and dense compared to the exosphere at higher altitudes. The 
DDRs give the averages of these fits as a function of true anomaly in 5 
degree increments.

The column density N (cm^-2) is derived from radiance I (kR) using

      N = I/(g 10^6)                                    (1)

The g-value is the rate (s^-1) at which an atom scatters sodium D1 and D2 
solar photons. It depends on distance from, and radial velocity relative to, 
the Sun. The sodium atoms have a distribution of speeds, but because this 
distribution is relatively narrow for the low-altitude, low-temperature 
portion of the exosphere described in this data product, we use Mercury's 
radial velocity and distance from the Sun to calculate g. 

The exospheric column density is related to the density via

      N = KHn                                           (2)

where n is the density of the exosphere at the line-of-sight tangent point, 
H is the scale height of the exosphere, and K is the ratio between the 
line-of-sight column density and the vertical column density (~Hn) and 
given, approximately, by [pi*r/(2H)]^1/2. These formulas come from 
Chamberlain (1963).

The density is approximated by

      n = n0e^-(U/kT)                                   (3)

where U is the gravitational potential energy due to gravity and photon 
acceleration, T the temperature, and n0 the surface density (see Feynman 
(1963) for a general discussion of this formula). The temperature and 
surface density are the free parameters of our fits to the limb scans and 
are provided in the DDR.

Photon acceleration (also called photon pressure or radiation pressure) is 
an antisunward acceleration due to the resonant scattering of sunlight. It 
is directly proportional to the g-value. At Mercury, for sodium, it can be 
nearly half as large as surface gravity (e.g., Wang and Ip, 2011). For that 
reason we included it along with the gravitational potential term in 
Eq. (1), so that the potential energy is written as

      U = GMm/r + mbrcos(theta)                         (4)

as described in Bishop (1985), where b is the photon acceleration, theta is 
the angle between the local radial vector and the Mercury-Sun axis, G is the 
gravitational constant, M is the mass of Mercury, m is the mass of a sodium 
atom, and r is the distance from Mercury's center. For each limbscan, 
because they all have line-of-sight tangent points near the equator, theta 
is derived, approximately, by the angular distance from noon as measured by 
the local time provided in the DDR.

The scale height, used in the formulas above and provided in the data 
product, is defined by

      H = n/(dn/dr) = kT/( GMm/r^2 + mbcos(theta) )     (5)

Note that in the absence of photon pressure and ignoring the radial 
variation in gravity, this definition reduces to the classic kT/ma, where a 
is gravitational acceleration. Alternately, we can write H as

      H = kT/m(a + bcos(theta) )                        (6)

where the parenthetical term in the denominator can be seen as a sum of two 
terms, the gravitational term and the radial component of the photon 
pressure. This scale height (measured in km) is also provided in the DDR.

Bishop, J., 1985. Geocoronal structure - The effects of solar radiation 
pressure and the plasmasphere interaction. Journal of Geophysical Research 
90, 5235-5245.

Chamberlain, J. W., 1963. Planetary coronae and atmospheric evaporation. 
Planetary and Space Science 11, 901.

Feynman, R. P., 1963.  Feynman lectures on physics - Volume 1, Chapter 40.  
Reading, Ma.: Addison-Wesley, 1963, edited by Feynman, Richard P.; Leighton, 
Robert B.; Sands, Matthew. 

Wang, Y. C. and W. H. Ip, 2011. Source dependency of exospheric sodium on 
Mercury. Icarus 216, 387-402.


5.3 Data Processing
5.3.1 Data Processing Level
The CDR/DDR archive includes level 3 (CDR) and level 4 (DDR) data as defined 
by the Committee on Data Management and Computation (CODMAC, Appendix I).  
The archive also contains calibration information, a description of the 
SPICE kernels that are needed to generate viewing geometry, and 
documentation describing the characteristics and generation of the data 
products.  Each product has a unique file name across all MASCS data 
products, see section 6.1.2.

5.3.2 Data Product Generation
The UVVS CDR/DDR files were produced by the MESSENGER Science Operations 
Center (SOC), operated jointly by APL and ACT.  The 'PIPE-MASCS2CDR' and 
'PIPE-MASCS2DDR' software, derived from MASCS-team produced calibration 
algorithms, converted the data to the proper PDS labeled format.  These 
software were not supported products deliverable to the PDS; however the 
algorithms and tables are included in the archive.  The CDR/DDR data 
products were made available to the MESSENGER Science Team during the 
mission for initial evaluation and validation.  At the end of the evaluation 
and validation period, the data were organized and stored in the directory 
structure described in section 6.1.3 for transmittal to the Geosciences and 
Atmospheres Nodes.  The transmittal process is described in the following 
section, Data Flow.  PDS provides public access to the data products through 
its online data distribution system.  These products are used for 
engineering support, direct science analysis, and construction of other 
science products.  Although there is enough information in the header to 
perform some processing, for more sophisticated processing, ancillary data 
are required.  Examples of ancillary data include calibration files and 
viewing geometry files (SPICE kernels).  Calibration files for UVVS are 
located in the CALIB directory.  Calibration and data reduction details and 
tables are described in the UVVS_EDR2CDR.TXT, UVVS_CDR2DDR.TXT, 
UVVS_CDR2DDR_SUR.TXT, and MASCS_CAL_RPT.TXT documents, located in the 
DOCUMENT directory.  The geometry.txt file located in the GEOMETRY 
directory (section 6.1.4) contains a listing of the SPICE kernel types that 
are needed by a user to generate viewing geometry.  The SPICE kernel files 
are archived with the PDS NAIF Node.

5.3.3 Data Flow
The MESSENGER SOC operated under the auspices of the MESSENGER Project 
Scientist to plan data acquisition and generate and validate data archives.  
The SOC supported and worked with the Mission Operations Center (MOC), the 
Science Team, instrument scientists, and the PDS (Figure 3).  The SOC was 
located at the Johns Hopkins University Applied Physics Lab (JHU/APL).  
During the mission operations phase, the SOC produced early versions of 
products to be used by the science and instrument teams. 

The MESSENGER SOC delivered data to both the PDS Geosciences and Atmospheres 
Nodes in standard product packages according to the schedule outlined in the 
MESSENGER Data Management and Archiving Plan [Applicable Document 4].  The 
UVVS and VIRS data sets are archived at both Nodes.  Each package comprises 
both data and ancillary data files, organized into directory structures 
consistent with the volume design described in Section 6.1.3.

In preparation for the delivery, the directory structure was copied onto 
hard disk and mailed to the Geosciences and Atmospheres PDS nodes.  Also 
transferred was a checksum file created using the MD5 algorithm.  This 
provided an independent method of verifying the integrity of the archive 
after it was transferred to disk.  Within several days of delivery, the PDS 
Node acknowledged receipt of the archive and checksum file.  If 
acknowledgement was not received, or if problems were reported, the 
MESSENGER SOC immediately took corrective action.

After receipt of the hard disk, the PDS Nodes transferred the archive files 
to their local archive staging areas and checked for data integrity using 
the checksum file.  The Nodes performed any additional verification and 
validation of the data provided and reported any discrepancies or problems 
to the MESSENGER SOC.  It was expected that the Nodes perform these checks 
in about two weeks.  After inspection was completed to the satisfaction of 
the PDS Nodes, the Nodes issued to the MESSENGER SOC acknowledgement of 
successful receipt of the data.

Following receipt of a data delivery, each Node organized the data into PDS 
archive volume structure within its online data system.  The Science Team 
generated all of the required files associated with a PDS archive volume 
(index file, readme files, etc.) as part of its routine processing of 
incoming MASCS data.  Newly delivered data were made available publicly from 
PDS once accompanying labels and other documentation were validated.

Changes and/or updates in instrument calibration resulted in an incremented 
calibration version number and regeneration of CDRs/DDRs. Regenerated data 
were included in the next scheduled delivery, as appropriate.

5.3.4 Labeling and Identification
The PDS label conforms to the PDS version 3 standards.  For more information 
on this standard consult the PDS Standards Reference JPL D-7669 Document 
[Applicable Document 3].  The purpose of the PDS label is to describe the 
data product and provide ancillary information about the data product.

One UVVS observation is associated with two CDR data products: a science 
header table (HDR), showing the instrument command parameters for a given 
observation, and a science data table (SCI), showing counts, science data at 
various stages of calibration, and pointing information for each step of an 
observation. The CDRs are in binary table format, and each is described by a 
detached PDS label. There are six standard data products, "UVVSCFUVHDR," 
"UVVSCFUVSCI," "UVVSCMUVHDR," "UVVSCMUVSCI," "UVVSCVISHDR," and 
"UVVSCVISSCI" (Section 5.2). 

UVVS Surface DDRs consist of individual scans with the FUV or MUV channel 
where the spacecraft attempts to maintain the instrument boresight on a 
fixed location during the entire grating scan.  Two data files (header and 
science) are produced for any one observation; for the FUV they are named 
"UVVSDFUVHDR" and "UVVSDFUVSCI" while for the MUV they are "UVVSDMUVHDR" and 
"UVVSDMUVSCI".

The UVVS Atmosphere DDRs consist of time-ordered sequences of calibrated 
spectra and radiance values that are measured along lines of sight 
perpendicular to Mercury radius vectors. The Atmosphere DDRs are in binary 
format and each is described by a detached PDS label. Each file contains N 
records where N is the number of sequential steps recovered from the 
filtering process. There are nine standard geometry-classified Atmosphere 
DDRs produced from the CDRs: the dayside limb scans, the dayside and 
nightside limb drift profiles, and nightside tail sweeps.  These are 
identified as "UVVSDNALS," "UVVSDNALD," and "UVVSDNANS" for sodium.  Names 
for Mg and Ca are produced by replacing 'NA' with 'MG' and 'CA', 
respectively.  These nine products are produced for each Mercury year that 
MESSENGER was in orbit about Mercury, with the first and last years being 
partial years owing to a year "starting" at Mercury true anomaly 0 degrees.  
There are also three standard orbit-level summary Atmosphere DDRs produced 
from the CDRs.  These are identified as "UVVSDNASUM", "UVVSDCASUM", and 
"UVVSDMGSUM".  These three products are produced for every MESSENGER orbit 
about Mercury during which data for the given species were acquired.

The UVVS Atmospheric Model DDRs consist of average fits to observations at a 
series of Mercury true anomaly and local times.  The model parameters 
near-surface density, temperature, and scale height are provided.  The data 
are provided in an ASCII table format.  There are 3 atmospheric model DDRs, 
identified as "UVVSDNAMOD", "UVVSDMGMOD", and "UVVSDCAMOD" for the sodium, 
magnesium, and calcium models, respectively.

The following are examples of UVVS PDS labels for the "UVVSFUVHDR" and 
"UVVSFUVSCI" CDR data products and the "UVVSDMUVHDR", "UVVSDMUVSCI", 
"UVVSDFUVHDR", "UVVSDFUVSCI", "UVVSDNALS", "UVVSDCASUM", and "UVVSDNAMOD" 
DDR data products, respectively. Details about the label format are 
specified in section 6.3. 

The UVVS+VIRS Combined DDR label and format are described in a separate 
specification document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the 
DOCUMENT directory of this volume.

5.3.4.1 Example PDS Label for the UVVS Science Header CDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 50
FILE_RECORDS                   = 480

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UFC_MC4_07_09343_064005_HDR_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2010-07-28T19:53:37
PRODUCT_TYPE                   = "CDR"
SOFTWARE_NAME                  = "PIPE-MASCS2CDR"
SOFTWARE_VERSION_ID            = "2.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-3-UVVS-CDR-CALDATA-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSCFUVHDR"
MISSION_PHASE_NAME             = "MERCURY 4 CRUISE"
TARGET_NAME                    = "VENUS"
TARGET_DESC                    = "Venus-As-Star Cal"
START_TIME                     = 2009-12-09T06:40:05
STOP_TIME                      = 2009-12-09T10:08:02
SPACECRAFT_CLOCK_START_COUNT   = "168828279.009"
SPACECRAFT_CLOCK_STOP_COUNT    = "168840756.989"
^TABLE                         = "UFC_MC4_07_09343_064005_HDR.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 23
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 50
   ROWS                           = 480
   DESCRIPTION                    = "
       This table contains instrument engineering data collected by the
       FUV detector.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR SIS document.

       The complete column definitions are contained in an external file
      found in the LABEL directory of the archive volume.   
   "
   ^STRUCTURE = "UVVSHDRC.FMT" 
END_OBJECT                     = TABLE
END
 
5.3.4.2 Example PDS Label for the UVVS Science CDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 752
FILE_RECORDS                   = 1216

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UFC_ORB_29_12056_051641_SCI_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2012-03-26T18:13:40
PRODUCT_TYPE                   = "CDR"
SOFTWARE_NAME                  = "PIPE-MASCS2CDR"
SOFTWARE_VERSION_ID            = "9.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-3-UVVS-CDR-CALDATA-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSCFUVSCI"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
OBSERVATION_TYPE               = {"LimbOpp","ExoScan"}
START_TIME                     = 2012-02-25T05:16:41
STOP_TIME                      = 2012-02-25T05:22:26
SPACECRAFT_CLOCK_START_COUNT   = "238634468.125"
SPACECRAFT_CLOCK_STOP_COUNT    = "238634813.953"
^TABLE                         = "UFC_ORB_29_12056_051641_SCI.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 63
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 752
   ROWS                           = 1216
   DESCRIPTION                    = "
       This table contains MESSENGER UVVS spectra collected by the 
       FUV detector and instrument engineering data.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR SIS document.

       The complete column definitions are contained in an external file
       found in the LABEL directory of the archive volume.   
   "  
   NOTE                           = "
     SPICE Kernels:
     msgr20120224.bc
     msgr20120225.bc
     msgr20120226.bc
     msgr_dyn_v600.tf
     msgr_v210.tf
     msgr_mascs_v100.ti
     naif0010.tls
     pck00009_MSGR_v10.tpc
     messenger_1444.tsc
     msgr_de405_de423s.bsp
     msgr_20040803_20140820_od259sc_0.bsp
   "

   ^STRUCTURE = "UVVSSCIC.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.3 Example PDS Label for the UVVS MUV Surface Header DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 36
FILE_RECORDS                   = 1

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UMD_ORB_48_11112_111324_HDR_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2013-05-31T19:53:37
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDMUVHDR"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
TARGET_DESC                    = "UVVS SURFACE OBSERVATION"
START_TIME                     = 2011-04-22T11:13:26
STOP_TIME                      = 2011-04-22T11:13:31
SPACECRAFT_CLOCK_START_COUNT   = "1/211958275"
SPACECRAFT_CLOCK_STOP_COUNT    = "1/211958280"
^TABLE                         = "UMD_ORB_48_11112_111324_HDR.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 16
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 36
   ROWS                           = 1
   DESCRIPTION                    = "
       This table contains instrument engineering data collected by the
       MUV detector. Each record contains the values over a single UVVS
       observation. A UVVS observation is defined as all the scan data
       contained within one UVVS science packet.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR-DDR SIS document.

       The complete column definitions are contained in an external file
      found in the LABEL directory of the archive volume.   
   "
   ^STRUCTURE = "UVVSHDRD_SUR.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.4 Example PDS Label for the UVVS MUV Surface Science DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 270
FILE_RECORDS                   = 46

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UMD_ORB_48_11112_111324_SCI_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2012-03-26T18:13:40
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDMUVSCI"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
OBSERVATION_TYPE               = "UVVSPhotometry"
START_TIME                     = 2011-04-22T11:13:26
STOP_TIME                      = 2011-04-22T11:13:31
SPACECRAFT_CLOCK_START_COUNT   = "1/211958275"
SPACECRAFT_CLOCK_STOP_COUNT    = "1/211958280"
^TABLE                         = "UMD_ORB_48_11112_111324_SCI.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 25
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 270
   ROWS                           = 46
   DESCRIPTION                    = "
       This table contains MESSENGER UVVS spectra collected by the 
       MUV detector and instrument engineering data.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR-DDR SIS document.

       The complete column definitions are contained in an external file
       found in the LABEL directory of the archive volume.   
   "  
   NOTE                           = "
     SPICE Kernels:
     msgr20110421.bc
     msgr20110422.bc
     msgr20110423.bc
     msgr_dyn_v600.tf
     msgr_v220.tf
     msgr_mascs_v100.ti
     naif0010.tls
     pck00010_MSGR_v10.tpc
     messenger_1728.tsc
     msgr_de405_de423s.bsp
     msgr_20040803_20140822_od301sc_0.bsp
   "

   ^STRUCTURE = "UVVSSCID_SUR.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.5 Example PDS Label for the UVVS FUV Surface Header DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 36
FILE_RECORDS                   = 2

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UFD_ORB_63_11333_234230_HDR_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2016-08-11T09:41:37
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDFUVHDR"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
TARGET_DESC                    = "UVVS SURFACE OBSERVATION"
START_TIME                     = 2011-11-29T23:42:36
STOP_TIME                      = 2011-11-29T23:42:43
SPACECRAFT_CLOCK_START_COUNT   = "1/231097622.669"
SPACECRAFT_CLOCK_STOP_COUNT    = "1/231097629.771"
^TABLE                         = "UFD_ORB_63_11333_234230_HDR.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 16
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 36
   ROWS                           = 2
   DESCRIPTION                    = "
       This table contains instrument engineering data collected by the
       FUV detector. Each record contains the values over a single UVVS
       observation. A UVVS observation is defined as all the scan data
       contained within one UVVS science packet.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR-DDR SIS document.

       The complete column definitions are contained in an external file
      found in the LABEL directory of the archive volume.   
   "
   ^STRUCTURE = "UVVSHDRD_SUR.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.6 Example PDS Label for the UVVS FUV Surface Science DDR

DS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 270
FILE_RECORDS                   = 2

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UFD_ORB_63_11333_234230_SCI_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2016-08-11T09:50:02
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDFUVSCI"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
OBSERVATION_TYPE               = "UVVSSurfaceTarget"
START_TIME                     = 2011-11-29T23:42:36
STOP_TIME                      = 2011-11-29T23:42:43
SPACECRAFT_CLOCK_START_COUNT   = "1/231097622.669"
SPACECRAFT_CLOCK_STOP_COUNT    = "1/231097629.771"
^TABLE                         = "UFD_ORB_63_11333_234230_SCI.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 26
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 270
   ROWS                           = 2
   DESCRIPTION                    = "
       This table contains MESSENGER UVVS spectra collected by the 
       FUV detector and instrument engineering data.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR-DDR SIS document.

       The complete column definitions are contained in an external file
       found in the LABEL directory of the archive volume.   
   "  
   NOTE                           = "
     SPICE Kernels:
     msgr20111128.bc
     msgr20111129.bc
     msgr20111130.bc
     msgr_dyn_v600.tf
     msgr_v231.tf
     msgr_mascs_v100.ti
     naif0011.tls
     pck00010_MSGR_v21.tpc
     messenger_2548.tsc
     msgr_20040803_20150430_od431sc_2.bsp
   "

   ^STRUCTURE = "UVVSSCID_FUV_SUR.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.7 Example PDS Label for the UVVS Atmosphere DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 906
FILE_RECORDS                   = 1234

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UD_05_LS_NA_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2013-01-14T15:02:30
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDNALS"
MISSION_PHASE_NAME             = "MERCURY ORBIT YEAR 2"
TARGET_NAME                    = "MERCURY"
OBSERVATION_TYPE               = "LimbScan"
START_TIME                     = 2013-12-09T06:40:05
STOP_TIME                      = 2013-12-09T10:08:02
SPACECRAFT_CLOCK_START_COUNT   = "268828279.009"
SPACECRAFT_CLOCK_STOP_COUNT    = "268840756.989"
^TABLE                         = "UD_05_LS_NA.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 30
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 906
   ROWS                           = 1234
   DESCRIPTION                    = "
       This table contains dayside limb scan data collected by the UVVS for a 
       given Mercury year.
    
       Detailed descriptions for the parameters defined below are contained
       in the CDR/DDR SIS document.

       The complete column definitions are contained in an external file
       found in the LABEL directory of the archive volume.   
   " 
   ^STRUCTURE = "UVVSSCID.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.8 Example PDS Label for the UVVS Atmosphere Summary DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 908
FILE_RECORDS                   = 496

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UD_01_ORB0133_11144_SUMMARY_CA_DAT"
PRODUCT_VERSION_ID             = "V1 "
PRODUCT_CREATION_TIME          = 2016-07-20T07:38:57
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDCASUM"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
OBSERVATION_TYPE               = 
   {"UVVSLimbOpp","UVVSNightColumn","UVVSExoScan","UVVSExoStare"}
START_TIME                     = 2011-05-23T21:31:02.86
STOP_TIME                      = 2011-05-24T08:00:56.86
SPACECRAFT_CLOCK_START_COUNT   = "1/214673731.141"
SPACECRAFT_CLOCK_STOP_COUNT    = "1/214711525.141"
^TABLE                         = "UD_01_ORB0133_11144_SUMMARY_CA.DAT"

OBJECT                         = TABLE
   COLUMNS                        = 30
   INTERCHANGE_FORMAT             = BINARY
   ROW_BYTES                      = 908
   ROWS                           = 496
   DESCRIPTION                    = "
       This table contains data collected by the UVVS for a given Mercury
       orbit.
       
       Detailed descriptions for the parameters defined below are contained
       in the CDR/DDR SIS document.

       The complete column definitions are contained in an external file
       found in the LABEL directory of the archive volume.   
   "  

   ^STRUCTURE = "UVVSSUMD.FMT" 
END_OBJECT                     = TABLE
END

5.3.4.9 Example PDS Label for the UVVS Atmospheric Model DDR

PDS_VERSION_ID                 = "PDS3" 

/*** FILE FORMAT ***/
RECORD_TYPE                    = FIXED_LENGTH
RECORD_BYTES                   = 128
FILE_RECORDS                   = 504

/*** GENERAL DATA DESCRIPTION PARAMETERS ***/
PRODUCT_ID                     = "UD_NA_MOD_TAB"
PRODUCT_VERSION_ID             = "V1"
PRODUCT_CREATION_TIME          = 2014-02-18T16:23:13
PRODUCT_TYPE                   = "DDR"
SOFTWARE_NAME                  = "PIPE-MASCS2DDR"
SOFTWARE_VERSION_ID            = "1.0"
INSTRUMENT_HOST_NAME           = "MESSENGER"
INSTRUMENT_NAME                = "
 MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER"
INSTRUMENT_ID                  = "MASCS"
DETECTOR_ID                    = "UVVS"
DATA_SET_ID                    = "MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0"
STANDARD_DATA_PRODUCT_ID       = "UVVSDNAMOD"
MISSION_PHASE_NAME             = "MERCURY ORBIT"
TARGET_NAME                    = "MERCURY"
START_TIME                     = 2011-04-04T21:02:28
STOP_TIME                      = 2013-03-17T23:51:20
SPACECRAFT_CLOCK_START_COUNT   = "1/210438416.311"
SPACECRAFT_CLOCK_STOP_COUNT    = "2/005888279.695"
^TABLE                         = "UD_NA_MOD.TAB"

OBJECT                         = TABLE
  COLUMNS                      = 9
  INTERCHANGE_FORMAT           = ASCII
  ROW_BYTES                    = 128
  ROWS                         = 504
  DESCRIPTION                  = "                                            
   The table contains a series of model fits to data averaged over 
   specific Mercury true anomalies and local times for sodium.
   The table contains data processed from UVVS CDRs for the time period
   specified by START_TIME and END_TIME in the PDS label.
   "                       

  OBJECT                       = COLUMN
    NAME                       = TRUE_ANOMALY
    COLUMN_NUMBER              = 1
    START_BYTE                 = 1
    BYTES                      = 7
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F7.3"
    DESCRIPTION                = "Mercury orbital position in degrees. Fit 
    parameters are provided as averages over 5 degree increments, the middle
    of that 5 degree increment is listed in the file (e.g. 2.5 degrees for 
    the 0-5 degree bin)."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = LOCAL_TIME
    COLUMN_NUMBER              = 2
    START_BYTE                 = 9
    BYTES                      = 6
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F6.3"
   DESCRIPTION                 = "Local time of the model fit. Only limb
   scans taken within half an hour of the given local time are included in
   the average."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = NEAR_SURFACE_DENSITY
    COLUMN_NUMBER              = 3
    START_BYTE                 = 16
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Average near-surface density from modified
    Chamberlain model fits. A value of -1 indicates no model fit for this
    combination of TRUE_ANOMALY and LOCAL_TIME. Units of cm-3."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = NEAR_SURFACE_DENSITY_UNCERTAINTY
    COLUMN_NUMBER              = 4
    START_BYTE                 = 32
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Average one-sigma standard deviation of the
    fit to near-surface density. A value of -1 indicates no model fit for 
    this combination of TRUE_ANOMALY and LOCAL_TIME. Units of cm-3."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = TEMPERATURE
    COLUMN_NUMBER              = 5
    START_BYTE                 = 48
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Average temperature modified from 
    Chamberlain model fits. A value of -1 indicates no model fit for this
    combination of TRUE_ANOMALY and LOCAL_TIME. Units of K."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = TEMPERATURE_UNCERTAINTY
    COLUMN_NUMBER              = 6
    START_BYTE                 = 64
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Average one-sigma standard deviation of the
    fit to temperature. A value of -1 indicates no model fit for this
    combination of TRUE_ANOMALY and LOCAL_TIME. Units of K."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = SCALE_HEIGHT
    COLUMN_NUMBER              = 7
    START_BYTE                 = 80
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Scale height corresponding to the model
    fit. A value of -1 indicates no model fit for this combination of
    TRUE_ANOMALY and LOCAL_TIME. Units of km."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = SPARE_1
    COLUMN_NUMBER              = 8
    START_BYTE                 = 96
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Spare column, placeholder for future
    parameter. Default to spare value of 0.000000."
  END_OBJECT = COLUMN

  OBJECT                       = COLUMN
    NAME                       = SPARE_2
    COLUMN_NUMBER              = 9
    START_BYTE                 = 112
    BYTES                      = 15
    DATA_TYPE                  = ASCII_REAL
    FORMAT                     = "F15.6"
    DESCRIPTION                = "Spare column, placeholder for future
    parameter. Default to spare value of 0.000000."
  END_OBJECT = COLUMN

END_OBJECT                     = TABLE
END


5.4 Standards Used in Generating Data Products
5.4.1 PDS Standards
The UVVS CDR/DDR data products were constructed according to the data object 
concepts developed by the PDS.  By adopting the PDS standards, the data 
products are consistent in content and organization with other planetary 
data collections.  The UVVS CDR and Surface DDR data are grouped into fours: 
a binary table of science data, a binary table of science header 
information, and detached PDS labels describing each of the binary tables.  
The UVVS Atmosphere and Atmosphere Summary data are grouped into pairs: a 
table of binary data and a detached PDS label describing the data.  The UVVS 
Atmospheric Model data are provided as ASCII tables (*.TAB) with detached 
PDS labels.

5.4.2 Time Standards
The SC_TIME field matches the spacecraft time in integer seconds that is 
transmitted to MESSENGER subsystems by the Integrated Electronics Module 
(IEM).  It is intended to be the Mission Elapsed Time (MET).  MET = 0 is 
August 3, 2004, at 05:59:16UTC, which is 1000 seconds prior to the MESSENGER 
launch.  Relativistic effects and circumstances occurring during the mission 
would result in MET not being a true account of seconds since launch.  
Following a planned spacecraft clock reset in early 2013, partition numbers 
(1/, or 2/) were added to product labels to disambiguate MET seconds after 
the spacecraft clock reset (if partition number is not present, SPICE 
defaults to partition 1/). The SPICE spacecraft clock coefficients file (see 
Appendix H) should be used to calculate the conversion between MET and UTC. 
Product label files express MET in 
<met_partition>/<met_seconds>.<met_milliseconds> format (note: MET 
milliseconds are only used in CDR and DDR product labels). UTC times in some 
products had a 1-second quantization issue before PDS Delivery 12 that has 
been solved (and the affected products redelivered).

5.4.3 Coordinate Systems
The computational assumptions for the geometric and viewing data provided in 
the PDS label are listed below.  There are two coordinate systems in use: 
1) the celestial reference system used for target and spacecraft position 
and velocity vectors; and 2) the planetary coordinate system for geometry 
vectors and target location.  The celestial coordinate system is J2000 (Mean 
of Earth equator and equinox of J2000).  The planetary coordinate system is 
planetocentric.

* For individual spectra in VIRS and individual steps in UVVS, the midpoint 
of the observation is used for determination of most geometric elements 
(such as center of observation, subspacecraft latitude/longitude/altitude, 
etc.). For VIRS, the "leading" and "trailing" point of the footprint smear 
use interpolation of the start and end time of the observation. 

* Label parameters reflect observed, not true, geometry. Therefore, 
light-time and stellar aberration corrections are used as appropriate.

* The inertial reference frame is J2000 (also called EME2000).

* Latitudes and longitudes are planetocentric. 

* The "sub-point" of a body on a target is defined by the surface intercept 
of the body-to-target-center vector.  This is not the closest point on the 
body to the observer.  

* Distances are in km, speeds in km/sec, angles in degrees, angular rates in 
degrees/sec, unless otherwise noted.

* Angle ranges are 0 to 360 degrees for azimuths and local hour angle. 
Longitudes range from 0 to 360 degrees (positive to the East).  Latitudes 
range from -90 to 90 degrees.

* SPICE kernel files used in the geometric parameters are outlined in 
APPENDIX H- SPICE Kernel Files Used in MESSENGER Data Products.
         
5.4.4 Data Storage Conventions
The data are organized following PDS standards and stored on hard disk and 
an SQL (Structured Query Language) relational database for rapid access 
during mission operations.  The MESSENGER SOC transfers data to PDS via 
electronic transfer and delivery methods as detailed in section 5.3.3.  
After verification of the data transfer, PDS provides public access to 
MESSENGER science data products through its online data distribution system. 
Data are stored under a unique file name as defined in section 6.1.2.


5.5 Data Validation
The UVVS CDR/DDR data products are validated by the UVVS Instrument 
Scientist for science content and for compliance with PDS archive standards 
and the MESSENGER Data Management and Archiving Plan [Applicable Document 4].



6. Detailed Data Product Specifications
6.1 Data Archive Structure and Organization
The UVVS EDR data set is a static dataset.  Static data sets, once produced 
and validated, are not subject to update or modification.  The UVVS CDR/DDR 
data set is a dynamic dataset.  Dynamic data sets have the inherent property 
that they continue to evolve and improve as the knowledge of the mission 
parameters improve.  These data sets are periodically updated or replaced 
with new versions, and are likely to be updated by post-mission data 
analysis programs.  As an example, the calibration files continue to evolve 
as knowledge of the MASCS sensor, as well as of the pointing accuracy of the 
MESSENGER spacecraft, improves.

6.1.1 Handling Errors
It is inevitable that errors are introduced into the archive even with data 
validation procedures applied to the volumes.  As errors were discovered, 
they are reported to the MESSENGER SOC. An errata report file (ERRATA.TXT), 
located in the ROOT directory, was maintained to track and document all 
discovered errors during the mission, including any CDRs/DDRs that were 
revised during the course of the mission.  Revised CDRs/DDRs or CDRs/DDRs 
that were missing from a previous PDS delivery were provided at the next 
scheduled PDS delivery or at the final PDS delivery as needed.  PDS replaces 
the outdated files with the revised files when provided in the data 
directories of the archive volume.

MASCS followed similar procedures as other instruments have historically. 
The CONFIDENCE_LEVEL_NOTE in the uvvs_cdr/ddr_ds.cat files located in the 
CATALOG directory was updated with each regeneration, and CDR/DDR 
regenerations were delivered at normal periodic delivery times.  
Redeliveries followed the same pattern as standard deliveries. As SPICE 
kernels were updated periodically, updated pointing information flowed down 
to CDR/DDR geometry fields of all CDRs/DDRs. File delivery manifests were 
provided with deliveries, including MD5 checksums.

6.1.2 File Naming Conventions
The file names developed for PDS data volumes are restricted to a 
36-character file name and a 3-character extension name with a period 
separating the file and extension names.  

The general form of the UVVS CDR and Surface DDR file name is 
"UdL_mmm_XX_YYDDD_HHMMSS_xxx" where:

     U: UVVS
     d: detector. F = FUV, M = MUV, V = VIS
     L: data-level. E = EDR, C = CDR, D = DDR
   mmm: mission phase
        EAC = Earth cruise to Earth flyby
        EAF = Earth flyby
        VC1 = cruise, post Earth flyby to pre-Venus 1 flyby
        VF1 = Venus 1 flyby
        VC2 = cruise, post Venus 1 to pre-Venus 2 flyby
        VF2 = Venus 2 flyby
        MC1 = cruise, post Venus 2 to pre-Mercury 1 flyby
        MF1 = Mercury 1 flyby
        MC2 = cruise, post Mercury 1 to pre-Mercury 2 flyby
        MF2 = Mercury 2 flyby
        MC3 = cruise, post Mercury 2 to pre-Mercury 3 flyby
        MF3 = Mercury 3 flyby
        MC4 = cruise, post Mercury 3 to pre-orbit insertion
        ORB = Orbit insertion until end of nominal orbit mission
        OB2 = Extended mission (orbit year 2)
        OB3 = Extended mission (orbit year 3)
        OB4 = Extended mission (orbit year 4)
        OB5 = Extended mission (orbit year 5)
    XX: two digit macro id. Value 00 for data created prior to the    
        existence of UVVS macros or when PIPE cannot determine the macro 
        id used. Value 48 or 49 for surface observations.
    YY: The last two digits of the year in which the data were acquired.
   DDD: The three digit day of year in which the data were acquired.
HHMMSS: The 6 digit hour, minute, second of the start of the observation.
   xxx: data-type. HDR = per observation (science header) data, SCI = per  
        step (science CDR) or per bin (surface science DDR) data. 

The general form of the geometry-classified UVVS Atmosphere DDR file name 
is "UL_mm_XX_ss" where:

     U: UVVS
     L: data-level. D = DDR
    mm: mercury year
        01-04 = Primary mission
        05-09 = Extended mission (orbit year 2)
        10-13 = Extended mission (orbit year 3)
        14-17 = Extended mission (orbit year 4)
        18    = Extended mission (orbit year 5)
    XX: the record category
        LS = Dayside Limb Scan
        LD = Dayside and Nightside Limb Drift
        NS = Nightside Sweep 
    ss: species. NA = sodium, MG = magnesium, CA = calcium

The general form of the orbit-level summary UVVS Atmosphere DDR file name 
is "UL_mm_ORBnnnn_yyddd_SUMMARY_ss" where:

     U: UVVS
     L: data-level. D = DDR
    mm: mercury year
        01-04 = Primary mission
        05-09 = Extended mission (orbit year 2)
        10-13 = Extended mission (orbit year 3)
        14-17 = Extended mission (orbit year 4)
        18    = Extended mission (orbit year 5)
  nnnn: orbit number
    yy: The last two digits of the year during which the given orbit starts   
        (2011-2015)
   ddd: The three digit day of year during which the given orbit starts
    ss: species. NA = sodium, MG = magnesium, CA = calcium

The general form of the UVVS Atmospheric Model DDR file name is "UL_ss_XXX" 
where:

     U: UVVS
     L: data-level. D = DDR
    ss: species. NA = sodium, MG = magnesium, CA = calcium
   XXX: MOD = model

The file naming convention of the UVVS+VIRS Combined DDR products are 
described in a separate specification document, 
UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory of this 
volume.

6.1.3 
Directory Structure and Contents for MASCS CDR/DDR/DAP Archive Volume
The following illustrations (Figures 4a-4c) show the directory structure 
overview for the MASCS CDR/DDR/DAP archive volume.  A detailed description 
of the directory tree is provided in section 6.1.4.  Empty directories are 
not included on the volume.

Note that the volume contains both UVVS and VIRS CDRs/DDRs/DAPs.  Details 
for the VIRS CDRs/DDRs/DAPs are contained in the document 
VIRS_CDR_DDR_DAP_SIS.PDF, and details for the UVVS+VIRS Combined DDR are 
contained in the document UVVS_VIRS_COMBINED_DDR_SPEC.PDF, both located in 
the DOCUMENT directory.  This archive volume is stored at both the 
Atmospheres and Geosciences PDS Nodes.  

Figure 4a: Directory Structure Overview.

                                       <ROOT>                                 
_________________________________________|___________________________
    |          |        |        |       |       |       |       |   
<DOCUMENT> <CATALOG> <INDEX> <GEOMETRY>  |   <CALIB> <LABEL> <EXTRAS>
                                       <DATA>                                 
                                         |                                    
                             ____________|____________                        
                              |          |         |                          
                            <CDR>      <DDR>     <DAP>                        
                              |          |         |                          
                          [Fig. 4b]  [Fig. 4c]   <VIRS>


Figure 4b: CDR Directory Structure.
               <CDR>         
                 |           
                 |           
          <mission phase>    
                 |           
                 |           
          <MASCSYYYYMMDD>    
                 |           
          _______|_______    
          |             |    
       <UVVS>        <VIRS>  
          |             |    
 _________|___       ___|___ 
 |    |      |       |     | 
FUV  MUV    VIS     VIS   NIR
                       

Figure 4c: DDR Directory Structure.
                                    <DDR>                                    
                                      |                                      
                                      |                                      
                               <mission phase>                               
                                      |                                      
______________________________________|___________________________________   
   |                 |                |               |              |       
<UVVS_             <UVVS_           <UVVS_          <UVVS_         <VIRS>    
ATMOSPHERE>        SUMMARY_         SURFACE>        VIRS_            |       
   |               ATMOSPHERE>         |            COMBINED>        |       
___|_____________      |               |                |            |       
   |         |         |        <MASCSYYYYMMDD>         |     <MASCSYYYYMMDD>
<models> <mercury  <species>           |                |            |       
          year>        |            ___|___             |         ___|____   
                       |            |     |             |          |    |    
                   <mercury        FUV   MUV     <MASCSYYYYMMDD>  VIS  NIR   
                    year>                                                    


6.1.4 Directory Contents

<ROOT> Directory

This is the top-level directory of a volume. The following are files 
contained in the root directory.

AAREADME.TXT - General information file. Provides users with information 
about the MESSENGER MASCS data products. Directs user to other documents on 
the volume containing more detailed information.

VOLDESC.CAT - PDS file containing the VOLUME object. This gives a high-level
description of the contents of the volume. Information includes: production 
date, producer name and institution, volume ID, etc.

ERRATA.TXT - Text file for identifying and describing errors and/or 
anomalies found in the current volume, and possibly previous volumes of a 
set. Any known errors for the associated volume are documented in this file. 
This includes revised data products meant to replace data products in a 
previous PDS delivery. 


<DOCUMENT> Directory

This subdirectory contains the documentation that is needed in order to 
understand and analyze the data products. The documentation files exist in 
several formats in order to facilitate access to the documents. Updated 
documents include incrementing version numbers.

DOCINFO.TXT - Identifies and describes the function of each file in the 
DOCUMENT directory.

VIRS_CDR_DDR_DAP_SIS.PDF - The MASCS VIRS CDR/DDR/DAP SIS: "MESSENGER MASCS 
VIRS Calibrated Data Record, Derived Data Record, and Derived Analysis 
Product Software Interface Specification" in Adobe Acrobat format. Note 
that, in contrast to the .TXT version, the illustrations, tables, etc. 
display appropriately in this format.

VIRS_CDR_DDR_DAP_SIS.TXT - The MASCS VIRS CDR/DDR/DAP SIS: "MESSENGER MASCS 
VIRS Calibrated Data Record, Derived Data Record, and Derived Analysis 
Product Software Interface Specification" in ASCII text format. Only the 
text is provided; for illustrations, tables, etc. the PDF should be 
consulted.

VIRS_CDR_DDR_DAP_SIS.LBL - A detached PDS label that describes the text and 
PDF files.

UVVS_CDR_DDR_SIS.PDF - The MASCS UVVS CDR/DDR SIS: "MESSENGER MASCS UVVS 
Calibrated and Derived Data Record Software Interface Specification" in 
Adobe Acrobat format.  Note that, in contrast to the .TXT version, the 
illustrations, tables, etc. display appropriately in this format.

UVVS_CDR_DDR_SIS.TXT - The MASCS UVVS CDR/DDR SIS: "MESSENGER MASCS UVVS 
Calibrated and Derived Data Record Software Interface Specification" in 
ASCII text format. Only the text is provided; for illustrations, tables, 
etc. the PDF should be consulted.

UVVS_CDR_DDR_SIS.LBL - A detached PDS label that describes the text and PDF 
files.

UVVS_VIRS_COMBINED_DDR_SPEC.TXT - The MASCS UVVS/VIRS COMBINED DDR 
Specification: "MESSENGER MASCS UVVS+VIRS Combined Derived Data Record 
Specification" in ASCII text format. Only the text is provided; for 
illustrations, tables, etc. the PDF should be consulted.

UVVS_VIRS_COMBINED_DDR_SPEC.PDF - The MASCS UVVS/VIRS COMBINED DDR 
Specification: "MESSENGER MASCS UVVS+VIRS Combined Derived Data Record 
Specification" in Adobe Acrobat format. Note that, in contrast to the .TXT 
version, the illustrations, tables, etc. will display appropriately.

UVVS_VIRS_COMBINED_DDR_SPEC.LBL - A detached PDS label that describes the 
text and PDF files.

VIRS_EDR2CDR.TXT - Detailed procedures and tables for EDR to CDR calibration.

VIRS_EDR2CDR.LBL - The detached label for the calibration document.

UVVS_EDR2CDR.TXT - Detailed procedures and tables for EDR to CDR calibration.

UVVS_EDR2CDR.LBL - The detached label for the calibration document.

VIRS_CDR2DDR.TXT - Detailed procedures and tables for CDR to DDR data 
reduction.

VIRS_CDR2DDR.LBL - The detached label for the CDR to DDR document.

UVVS_CDR2DDR.TXT - Detailed procedures and tables for CDR to Atmosphere DDR 
data reduction. 

UVVS_CDR2DDR.LBL - The detached label for the CDR to Atmosphere DDR document.

UVVS_CDR2DDR_SUR.TXT - Detailed procedures and tables for CDR to Surface DDR 
data reduction. 

UVVS_CDR2DDR_SUR.LBL - The detached label for the CDR to Surface DDR 
document.

UVVSVIRS_DDR2DDR_COMBINED.TXT - Detailed procedures for UVVS-VIRS DDR to 
Combined DDR data reduction.

UVVSVIRS_DDR2DDR_COMBINED.LBL - The detached label for the UVVS-VIRS DDR to 
Combined DDR document.

MASCS_CAL_RPT.PDF - The MESSENGER instrument calibration report for MASCS, 
in Adobe Acrobat format.  Note that, in contrast to the .TXT version, the 
illustrations, tables, etc. display appropriately in this format.

MASCS_CAL_RPT.TXT - The MESSENGER instrument calibration report for MASCS, 
in ASCII text format. Only the text is provided; for illustrations, tables, 
etc. one of the other formats should be consulted.

MASCS_CAL_RPT.LBL - A detached PDS label that describes the text and PDF 
file.

VIRS_DARK_ANALYSIS_REPORT_1.PDF - "VIRS IR Dark Analysis Report 1: 
Operational Changes" in Adobe Acrobat format. Details the evolving 
understanding of MASCS dark current during Mercury orbit, describing 
temperature dependence and effects on the NIR data in particular. Note that, 
in contrast to the .TXT version, the illustrations, tables, etc. display 
appropriately in this format.

VIRS_DARK_ANALYSIS_REPORT_1.TXT - "VIRS IR Dark Analysis Report 1: 
Operational Changes" in ASCII text format. Details the evolving 
understanding of MASCS dark current during Mercury orbit, describing 
temperature dependence and effects on the NIR data in particular. Only the 
text is provided; for illustrations, tables, etc. the PDF should be 
consulted.

VIRS_DARK_ANALYSIS_REPORT_1.LBL - A detached PDS label that describes the 
text and PDF file.

VIRS_DARK_ANALYSIS_REPORT_2.PDF - "VIRS IR Dark Analysis Report 2: 
Calibration Changes" in Adobe Acrobat format. Describes the adjustments to 
MASCS calibration to improve dark subtraction and account for pixels 
saturated due to temperature. Note that, in contrast to the .TXT version, 
the illustrations, tables, etc. display appropriately in this format.

VIRS_DARK_ANALYSIS_REPORT_2.TXT - "VIRS IR Dark Analysis Report 2: 
Calibration Changes" in ASCII text format. Describes the adjustments to 
MASCS calibration to improve dark subtraction and account for pixels 
saturated due to temperature. Only the text is provided; for illustrations, 
tables, etc. the PDF should be consulted.

VIRS_DARK_ANALYSIS_REPORT_2.LBL - A detached PDS label that describes the 
text and PDF file.

VIRS_CALIBRATION CHANGES_PDS9.PDF - "VIRS Calibration changes for PDS 
delivery 9" in Adobe Acrobat format. Describes the calibration changes 
implemented to simplify the handling of dark subtractions for VIRS, and an 
adjustment to the DATA_QUALITY_INDEX provided in the data records.

VIRS_CALIBRATION CHANGES_PDS9.TXT - "VIRS Calibration changes for PDS 
delivery 9" in Adobe Acrobat format. Describes the calibration changes 
implemented to simplify the handling of dark subtractions for VIRS, and an 
adjustment to the DATA_QUALITY_INDEX provided in the data records.

VIRS_CALIBRATION CHANGES_PDS9.LBL - A detached PDS label that describes the 
text and PDF file.

UVVS_CALIBRATION_CHANGES_PDS7.PDF - "UVVS Calibration Changes for PDS 
Delivery 7" in Adobe Acrobat format. Describes the need for and method of 
removing solar background signal in several emission wavelength regions. 

UVVS_CALIBRATION_CHANGES_PDS7.TXT - "UVVS Calibration Changes for PDS 
Delivery 7" in ASCII text format. Describes the need for and method of 
removing solar background signal in several emission wavelength regions. 

UVVS_CALIBRATION_CHANGES_PDS7.LBL - A detached PDS label that describes the 
text and PDF file.

VIRS_CALIBRATION_CHANGES_PDS11.PDF - "VIRS Calibration Changes for PDS 
Delivery 11" in Adobe Acrobat format. Describes changes to the calibration 
procedure that have been implemented to remedy an observed shift in the 
wavelength scale of the VIRS visible channel. 

VIRS_CALIBRATION_CHANGES_PDS11.TXT - "VIRS Calibration Changes for PDS 
Delivery 11" in ASCII text format. Describes changes to the calibration 
procedure that have been implemented to remedy an observed shift in the 
wavelength scale of the VIRS visible channel. 

VIRS_CALIBRATION_CHANGES_PDS11.LBL - A detached PDS label that describes the 
text and PDF file.

UVVS_CALIBRATION_CHANGES_PDS11.PDF - "MESSENGER MASCS UVVS Calibration Update
- PDS 11" in Adobe Acrobat format. Describes the UVVS FUV CDR calibration 
sensitivity update. 

UVVS_CALIBRATION_CHANGES_PDS11.TXT - "MESSENGER MASCS UVVS Calibration Update
- PDS 11" in ASCII text format. Describes the UVVS FUV CDR calibration 
sensitivity update. 

UVVS_CALIBRATION_CHANGES_PDS11.LBL - A detached PDS label that describes the 
text and PDF file.

CALCIUM_CHAMBERLAIN_MODELS.PDF - Description of the calcium Chamberlain 
models in Adobe Acrobat format.

CALCIUM_CHAMBERLAIN_MODELS.TXT - Description of the calcium Chamberlain 
models in ASCII text format. Only the text is provided; for equations, 
tables, etc. the PDF should be consulted.

CALCIUM_CHAMBERLAIN_MODELS.LBL - A detached PDS label that describes the 
text and PDF file.

UVVS_PROCESSING_UPDATES_PDS16.PDF - "MESSENGER MASCS UVVS Processing Updates 
- PDS 16" in Adobe Acrobat format. Describes the UVVS CDR and DDR processing 
updates for PDS delivery 16.  

UVVS_PROCESSING_UPDATES_PDS16.TXT - "MESSENGER MASCS UVVS Processing Updates 
- PDS 16" in ASCII text format. Describes the UVVS CDR and DDR processing 
updates for PDS delivery 16. 

UVVS_PROCESSING_UPDATES_PDS16.LBL - A detached PDS label that describes the 
HTML and PDF file.

VIRS_FLATFIELD_REPORT.PDF - "MASCS/VIRS Lamp-Based Flat Field Report" in 
Adobe Acrobat Format. Describes the results of an investigation to derive a 
flat-field correction for the MASCS VIRS surface observations.

VIRS_FLATFIELD_REPORT.HTM - "MASCS/VIRS Lamp-Based Flat Field Report" in HTML 
Format. Describes the results of an investigation to derive a flat-field 
correction for the MASCS VIRS surface observations.

VIRS_FLATFIELD_REPORT.LBL - A detached PDS label that describes the HTML and 
PDF file.

VIRS_TUTORIAL.PDF - MASCS VIRS Tutorial/User's Guide in PDF/A format.

VIRS_TUTORIAL.LBL - A detached PDS label that describes the PDF/A file.


<CATALOG> Directory

This subdirectory contains the catalog object files for the entire volume. 
The following files are included in the catalog subdirectory.

CATINFO.TXT - Identifies and describes the function of each file in the 
catalog directory.

MISSION.CAT - Describes the scientific goals and objectives of the MESSENGER 
mission.

INSTHOST.CAT - Describes the MESSENGER spacecraft.

INST.CAT - Describes physical attributes of the MASCS instrument and 
provides relevant references to published literature.

UVVS_CDR_DS.CAT, VIRS_CDR_DS.CAT - Describes the general content of the 
MASCS UVVS and MASCS VIRS CDR datasets, and includes information about the 
duration of the mission and the person or group responsible for producing 
the data.

UVVS_DDR_DS.CAT, VIRS_DDR_DS.CAT - Describes the general content of the 
MASCS UVVS DDR and MASCS VIRS DDR datasets, and includes information about 
the duration of the mission and the person or group responsible for 
producing the data.    

VIRS_DAP_DS.CAT - Describes the general content of the MASCS VIRS DAP 
dataset, and includes information about the duration of the mission and the 
person or group responsible for producing the data.    

UVVS_VIRS_DDR_DS.CAT - Describes the general content of the MASCS UVVS+VIRS 
Combined DDR dataset.

DAP_MAP.CAT - Describes the DAP dataset equirectangular map projection.

PERSON.CAT - Lists and provides contact information for the people involved 
with the MASCS instrument on the MESSENGER mission.

REF.CAT - Contains the complete citations of references mentioned in the
above catalog files, along with citations of additional documents that may 
be useful to the person using the MASCS data.


<INDEX> Directory

This subdirectory contains the indices for all data products on the volume.  
The following files are contained in the index subdirectory.

INDXINFO.TXT - Identifies and describes the function of each file in the 
index subdirectory.

MD5.TAB - Provides the MD5 checksum (message digest) for each file in the 
archive, with the exception of the MD5.TAB file itself.

MD5.LBL - Detached PDS label for MD5.TAB.

VICINDEX.TAB - The VIRS CDR index file is organized as a table: there is one 
entry for each of the data files included in the VIRS data set; the columns 
contain parameters that describe the observation, instrument, and spacecraft 
parameters.

VICINDEX.LBL - Detached PDS label for VICINDEX.TAB.

VIDINDEX.TAB - The VIRS DDR index file is organized as a table: there is one 
entry for each of the data files included in the VIRS DDR data set; the 
columns contain parameters that describe the observation, instrument, and 
spacecraft parameters.

VIDINDEX.LBL - Detached PDS label for VIDINDEX.TAB.

VDAPINDEX.TAB - The VIRS DAP index file is organized as a table: there is 
one entry for each of the data files included in the VIRS DAP data set; the 
columns contain parameters that describe the observation, instrument, and 
spacecraft parameters.

VDAPINDEX.LBL - Detached PDS label for VDAPINDEX.TAB.

UHCINDEX.TAB - The UVVS CDR header index file is organized as a table: there 
is one entry for each of the data files included in the UVVS data set; the 
columns contain parameters that describe the observation, instrument, and 
spacecraft parameters.

UHCINDEX.LBL - Detached PDS label for UVCINDEX.TAB.

USCINDEX.TAB - The UVVS CDR science index file is organized as a table: 
there is one entry for each of the data files included in the UVVS data set; 
the columns contain parameters that describe the observation, instrument, 
and spacecraft parameters.

USCINDEX.LBL - Detached PDS label for UVCINDEX.TAB.

USDINDEX.TAB - The UVVS DDR science index file is organized as a table: 
there is one entry for each of the data files included in the UVVS DDR data 
set; the columns contain parameters that describe the observation, 
instrument, and spacecraft parameters.

USDINDEX.LBL - Detached PDS label for USDINDEX.TAB.

UVDINDEX.TAB - The UVVS+VIRS Combined DDR index file is organized as a 
table: there is one entry for each of the data files included in the 
UVVS+VIRS Combined DDR data set; the columns contain parameters that 
describe the observation, instrument, and spacecraft parameters.  

UVDINDEX.LBL - Detached PDS label for UVDINDEX.TAB.

Tables 3a-3d below list the columns in the UHCINDEX.TAB, USCINDEX.TAB, 
USDINDEX.TAB, and UVDINDEX.TAB files, respectively. They are the most 
significant keywords pulled from the labels of the various products. For any 
given data product, some of the fields are inapplicable and are set to N/A.

Table 3a: UHCINDEX.TAB Columns.
Table 3b: USCINDEX.TAB Columns.
Table 3c: USDINDEX.TAB Columns.
Table 3d: UVDINDEX.TAB Columns.
See PDF version of document for table.


<GEOMETRY> Directory 

This subdirectory contains information about the files (e.g. SPICE kernels, 
etc.) needed to describe the observation geometry for the data.

GEOMETRY.TXT - Identifies and describes the SPICE kernels that a user must 
have in order to determine observation geometry for the data. The SPICE 
kernel files are archived with the PDS NAIF node.


<CALIB> Directory 

This subdirectory contains a look up table for calibration.

CALINFO.TXT - Describes the contents of this directory.

UVVS_GRATING_OFFSET.TAB - Time tag table of UVVS grating offsets. A grating 
offset correction was implemented for PDS Release 16. This table is a record 
of the time periods relevant to and the magnitudes (in grating steps) of the 
offsets.

UVVS_GRATING_OFFSET.LBL - Detached PDS label for UVVS_GRATING_OFFSET.TAB.


<LABEL> Directory 

This subdirectory contains format files (label fragments) that are 
referenced in the PDS labels for data files. These format files define the 
structure and contents of the binary data tables. Software that interprets 
PDS labels automatically include these files to determine how to read the 
data.

LABINFO.TXT - Describes the contents of this directory.

VIRSVC.FMT - Format of the VIRS VIS (visible wavelength) CDR data table.

VIRSNC.FMT - Format of the VIRS NIR (near infrared wavelength) CDR data 
table.

VIRSVD.FMT - Format of the VIRS VIS (visible wavelength) DDR data table.

VIRSND.FMT - Format of the VIRS NIR (near infrared wavelength) DDR data 
table.

UVVSHDRC.FMT - Format of the UVVS CDR science header table file.

UVVSSCIC.FMT - Format of the UVVS CDR science data table file.

UVVSSCID.FMT - Format of the UVVS atmosphere science DDR data table.

UVVSSUMD.FMT - Format of the UVVS atmosphere summary DDR data table.

UVVSHDRD_SUR.FMT - Format of the UVVS surface header DDR data table.

UVVSSCID_SUR.FMT - Format of the UVVS MUV surface science DDR data table.

UVVSSCID_FUV_SUR.FMT - Format of the UVVS FUV surface science DDR data 
table.

UVVSVIRSD.FMT - Format of the UVVS+VIRS Combined DDR data table.


<EXTRAS> Directory

This subdirectory contains ancillary material that may be useful but is not 
required for the understanding of the archive.

VIRS_AV/ - This subdirectory contains the VIRS animated visualization 
products, organized by mission phase and provided in .MP4 format. 
VIRS_AV_DESCRIPTION.PDF describes these products in detail.

VIRS_MISSING_PACKETS_R6.TXT - This file describes the investigation and 
resolution of the missing packet error described in the "Data Coverage and 
Quality" section of VIRS_CDR_DS.CAT. Included is a list of the EDRs (and 
thus also CDRs) missing packets for PDS release 6. 

VIRS_VIS_EDR_MISSING_PACKET_ANALYSIS_R6.XLS - This is a companion 
spreadsheet to the file above. It shows a detailed breakdown of the EDRs and 
exactly which packets are missing.

VIRS_VIS_MISSING_PACKETS_R*.TXT - These files list the incomplete VIRS VIS 
EDRs/CDRs for PDS releases, where '*' is the release #. The errors are 
described in the "Data Coverage and Quality" section of VIRS_CDR_DS.CAT.  

VIRS_NIR_MISSING_PACKETS_R*.TXT - These files list the incomplete VIRS NIR 
EDRs/CDRs for PDS releases, where '*' is the release #. The errors are 
described in the "Data Coverage and Quality" section of VIRS_CDR_DS.CAT. 

MASTER_CRUISE_TABLE.XLS - This is an extended instrument operation table 
used during cruise and flyby operations of MASCS, showing details of VIRS 
and UVVS observations, times, and other information useful for quick 
reference. In orbit, the mission planning software SCIBOX takes over the 
function of this table. This file can be viewed using Microsoft Excel.

VIRS_CDR_EXCLUDED.TXT - This is a list of VIRS CDRs that are excluded from 
PDS delivery due to bad dark solutions. See VIRS_CDR_DS.CAT for more 
information.

VIRS_DDR_EXCLUDED.TXT - This is a list of VIRS DDRs that are excluded from 
PDS delivery due to:
1) all footprints have shutter closed
2) all footprints are off planet
3) all footprints are in nightside shadow
4) bad dark solutions
See VIRS_DDR_DS.CAT for more information.


<DATA> Directory

This is the top level directory for the data products (see Figure 3a). 
Directly underneath the <DATA> directory are the <CDR>, <DDR>, and <DAP> 
directories.  Below the <DAP> directory is the <VIRS> subdirectory, wherein 
lies the VIRS DAP images (*.IMG) and associated PDS label (*.LBL). Below the 
<CDR> and <DDR> directories are the three-letter "mission phase" 
subdirectories, detailed in section 6.1.2 above.  

For the CDRs, below the mission phase directories are the <MASCSYYYYMMDD> 
directories, where the "YYYYMMDD" characters define the four-digit year, 
2-digit month, 2-digit day which is common to all the MET times for the CDRs 
stored in that directory. The <MASCSYYYYMMDD> directories are further 
subdivided into two subdirectories, <UVVS> and <VIRS>.  The <UVVS> 
subdirectory is divided into the detector subdirectories <FUV>, <MUV>, and 
<VIS> and the <VIRS> subdirectory into <VIS> and <NIR>. Within the detector 
subdirectories are the CDR data files themselves (*.DAT) and, for each CDR 
data file, a detached label file (*.LBL). Subdirectories only exist if that 
particular type of data exists for that day. If there are no data of a 
particular type for a particular day, no subdirectory is included for that 
type.

For the DDRs, below the mission phase directories are the <UVVS_ATMOSPHERE>, 
<UVVS_SUMMARY_ATMOSPHERE>, <UVVS_SURFACE>, <UVVS_VIRS_COMBINED>, and <VIRS> 
directories. The <UVVS_ATMOSPHERE> directory is further subdivided into 
directories based on the Mercury year of data acquisition (01-04 for primary 
mission, 05+ for extended mission). The <UVVS_SUMMARY_ATMOSPHERE> directory 
is subdivided into species directories which are further subdivided into 
directories based on Mercury year. Each of the <UVVS_SURFACE>, 
<UVVS_VIRS_COMBINED>, and <VIRS> directories is subdivided into 
<MASCSYYYYMMDD> date directories. The VIRS directories are further 
subdivided into <VIS> and <NIR> detector subdirectories following the 
structure of the VIRS CDRs. The <UVVS_SURFACE> directories are further 
subdivided into <FUV> and <MUV> detector subdirectories. Within the Mercury 
year (<UVVS_ATMOSPHERE>, <UVVS_SUMMARY_ATMOSPHERE>), date 
(<UVVS_VIRS_COMBINED>), and detector (<UVVS_SURFACE>, <VIRS>) subdirectories 
are the UVVS and VIRS DDR data files themselves (*.DAT), and, for each DDR 
data file, a detached label file (*.LBL). The atmospheric model data (*.TAB) 
and associated PDS labels (*.LBL) are located in the <models> directory 
beneath <ORB/UVVS_ATMOSPHERE>.


6.2 Data Format Description
Data are stored in binary and ASCII table format. Detached PDS labels 
provide detailed descriptions of the structure of the tables.


6.3 Label and Header Descriptions

6.3.1 CDR Column Descriptions
Each UVVS observation (contiguous time period of data acquisition with a 
given sequence) is associated with two CDR data products: a science header 
table (HDR), showing the instrument command parameters for a given 
observation, and a science data table (SCI), showing counts, derived science 
data, and pointing information for each step of an observation. The table 
columns are described by the format files UVVSHDRC.FMT and UVVSSCIC.FMT, 
respectively. The following are detailed descriptions of the columns in the 
UVVS CDR binary table objects. "OBSERVATION" columns have the same value for 
the whole CDR - these are parameters such as integration time set during the 
UVVS setup command. "PER STEP" columns have different values for each step 
in the observation. Times associated with individual steps refer to the 
middle of the integration period for that step. Replicas of the UVVSHDRC.FMT 
and UVVSSCIC.FMT format files can be found in Appendices A and B, 
respectively.

Note: All undefined field values (e.g., tangent altitudes do not exist if 
the line of sight is looking away from the planet) have been replaced with 
MISSING_CONSTANT = -1.E32, and all fields containing this value should be 
considered as undefined or meaningless.

6.3.1.1 Fields in Science Header CDR Format File (UVVSHDRC.FMT)

1. SEQ_COUNTER          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

CCSDS packet sequence counter. PER OBSERVATION column.

2. SC_TIME          
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Spacecraft time in integer seconds that is transmitted to the MESSENGER 
subsystems by the Integrated Electronics Module. This is assigned as the 
start time of the UVVS observation. A UVVS observation is defined as all the 
scan data contained within one UVVS science packet. This is due to the 
highly configurable nature of the instrument, i.e. it can be commanded to 
take multiple scans over multiple wavelengths. Unit is in mission elapsed 
time which is the number of seconds since launch. PER OBSERVATION column.

3. PACKET_SUBSECONDS          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

The subsecond time in milliseconds that the telemetry packet was initiated. 
SC_TIME plus PACKET_SUBSECONDS is the spacecraft time of the first 
integration. Values of this field are in units of 5 milliseconds. For 
example, a value of 10 refers to a time of 50 milliseconds. PER OBSERVATION 
column.

4. START_POS          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Start position where grating drive begins a scan. Grating drive step 
position corresponds to a given wavelength being observed by an instrument. 
PER OBSERVATION column.

5. STEP_COUNT          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of steps the grating drive took in a scan. This directly corresponds 
to the range of wavelengths that were observed in one UVVS observation. PER 
OBSERVATION column.

6. INT_TIME          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Integration time in grating drive loop control interrupt periods (nominally 
3000 Hz). For example, the actual integration time in seconds is 
INT_TIME/3000. PER OBSERVATION column.

7. STEP_TIME          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Step time in grating drive loop control interrupt periods (nominally 3000 
Hz). For example, the actual step time in seconds is STEP_TIME/3000. PER 
OBSERVATION column.

8. PHASE_OFFSET          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Phase offset in grating drive loop control interrupt periods.  Phase offset 
between the beginning of grating drive step and the start of a PMT 
integration in units of 0.3 milliseconds.  Default value is 0 (no phase 
offset).  Setting the phase offset to a non-zero value (reserved for 
contingency operations), instructed the software to initiate a step before 
the end of an integration, accounting for latencies in the motor 
controller. PER OBSERVATION column.

9. SCAN_CYCLES          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of times to repeat scan. PER OBSERVATION column.

10. ZIGZAG          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether grating drive moves in a 'triangle' (stepping up, then 
stepping down), or 'sawtooth' (stepping up, then 'flying' down) motion. A 
'triangle' observation takes one grating scan stepping up the grating, then 
reverses direction and takes the next grating scan stepping back down the 
grating. Scans in opposite directions are offset from one another by two 
grating step positions such that the wavelength ranges are slightly 
different. A 'sawtooth' observation takes one grating scan stepping up the 
grating, then 'flies' the grating back to the START_POSITION to take the 
next observation. =0 disable, =1 enable. PER OBSERVATION column.

11. COMPRESSION          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Selectable data size, =0 16 bit data, =1 9 bit data. Used to help determine 
the total number of data points contained in the observation. PER 
OBSERVATION column.

12. SLIT_MASK_POS        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether slit mask is in atmospheric (open) or surface (closed) 
position. Atmospheric slit results in a 1 deg. by 0.04 deg. instantaneous 
field of view (iFOV). Surface slit results in a 0.05 deg. by 0.04 deg. 
iFOV. =0 closed, =1 open. PER OBSERVATION column.

13. FUV_ON        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether FUV PMT power is on. A more complete description of this 
field can be found in the MASCS User's Guide (Applicable Document 6 in 
UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER OBSERVATION column.

14. MUV_ON        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether MUV PMT power is on. A more complete description of this 
field can be found in the MASCS User's Guide (Applicable Document 6 in 
UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER OBSERVATION column.

15. VIS_ON        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether VIS PMT power is on. A more complete description of this 
field can be found in the MASCS User's Guide (Applicable Document 6 in 
UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER OBSERVATION column.

16. BUFFER_OVERFLOW        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether scan programmed overflowed data buffer and was therefore 
truncated. =0 false, =1 true. PER OBSERVATION column.

17. SPARE_BITS        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

A two-byte spare location.

18. GD_SETTLE_CTR        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of times during integration that the grating drive wandered outside 
target range. This can happen very rarely with an encoder misread, or motor 
misstep, and would result in an offset of step-number to wavelength 
correlations for subsequent observations in a given scan. PER OBSERVATION 
column.

19. NUM_SCAN_VALUES        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Total number of values or data points in the entire scan observation. Used 
to determine the number of valid data points in the SCAN_DATA column. 
Maximum value is 3626. PER OBSERVATION column.

20. STEP_SIZE        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Step size in arcmin units. PER OBSERVATION column.

21. PAD_BYTE        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

A two-byte spare location. PER OBSERVATION column.

22. COADD        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of steps coadded to make a single observation. Default = 1, i.e. one 
step per observation. PER OBSERVATION column.

23. CALIBRATION_SOFTWARE_VERSION        
Bytes: 4        Type: IEEE_REAL

Indicates version of calibration software used. Increments with reprocessing 
of CDRs. PER OBSERVATION column.

6.3.1.2 Fields in Science Data CDR Format File (UVVSSCIC.FMT)

UVVS "corners" are the corners of the instantaneous field of view rectangle 
described by the atmospheric or surface slit. They are denoted throughout 
the geometry fields as c1, c2, c3, and c4, and shown schematically in 
Figures 5a and 5b. Relative to spacecraft axes, corner 1 (c1) is in the +y, 
+x corner of the field of view; c2 is -y, +x; c3 is -y, -x, and c4 is +y, 
-x. Figure 5c illustrates spacecraft position vectors in the planetocentric 
reference frame.

Figure 5a: UVVS Geometry Illustration. Exosphere Observations.
Figure 5b: UVVS Geometry Illustration. Surface (Ground) Observations. 
Fig. 5c: UVVS Position vectors in the planet-fixed coordinate frame. Two 
different types of observations are shown here on one figure.  For an 
exosphere scan, the boresight makes a right angle with a vector pointed 
radially from the center of the planet.  As defined here, the 'tangent' 
vector lies on this radial line and has a length equal to the radius of the 
planet, while the altitudes of the actual tangent points are given as a set 
of fixed values.  For a surface scan, the instrument boresight intersects 
the planet surface and the 'tangent' vector points to this location. For 
other flybys, Earth, Moon, or Venus is substituted for Mercury.
See PDF version of document for figures.

1. 
STEP_NUMBER        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Step in the observation. PER STEP column.

2. PLANET_SUN_VECTOR_TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet- sun position in 
target body-fixed coordinate system. Unit = kilometers. PER STEP column. 

3. PLANET_SC_VECTOR_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet- spacecraft position 
in target body-fixed coordinate system. Unit = kilometers. PER STEP column.

4. BORESIGHT_UNIT_VECTOR_CENTER_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS center in target 
body-fixed coordinate system. Unit = N/A. PER STEP column.

5. BORESIGHT_UNIT_VECTOR_C1_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS corner 1 in 
target body-fixed coordinate system. Unit = N/A. PER STEP column.

6. BORESIGHT_UNIT_VECTOR_C2_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS corner 2 in 
target body-fixed coordinate system. Unit = N/A. PER STEP column.

7. BORESIGHT_UNIT_VECTOR_C3_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS corner 3 in 
target body-fixed coordinate system. Unit = N/A. PER STEP column.

8. BORESIGHT_UNIT_VECTOR_C4_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS corner 4 in 
target body-fixed coordinate system. Unit = N/A. PER STEP column.

9. SURFACE_TANGENT_VECTOR_CENTER        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Vector from center of target planet through tangent line (a radial line 
which intersects the boresight look direction at a 90 deg. angle) to the 
planet surface, with a magnitude equal to the planet radius, UVVS Center. 
In target body-fixed coordinate system. Unit = kilometers. PER STEP column.

*Note: Value = MISSING_CONSTANT when pointing vector is >50 planetary radii 
from planet.

10. SURFACE_TANGENT_VECTOR_C1        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Vector from center of target planet through tangent line (a radial line 
which intersects the boresight look direction at a 90 deg. angle) to the 
planet surface, with a magnitude equal to the planet radius, UVVS Corner 1. 
In target body-fixed coordinate system. Unit = kilometers. PER STEP column.

*Note: Value = MISSING_CONSTANT when pointing vector is >50 planetary radii 
from planet.

11. SURFACE_TANGENT_VECTOR_C2        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Vector from center of target planet through tangent line (a radial line 
which intersects the boresight look direction at a 90 deg. angle) to the 
planet surface, with a magnitude equal to the planet radius, UVVS Corner 2. 
In target body-fixed coordinate system. Unit = kilometers. PER STEP column.

*Note: Value = MISSING_CONSTANT when pointing vector is >50 planetary radii 
from planet.

12. SURFACE_TANGENT_VECTOR_C3        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Vector from center of target planet through tangent line (a radial line 
which intersects the boresight look direction at a 90 deg. angle) to the 
planet surface, with a magnitude equal to the planet radius, UVVS Corner 3. 
In target body-fixed coordinate system. Unit = kilometers. PER STEP column.

*Note: Value = MISSING_CONSTANT when pointing vector is >50 planetary radii 
from planet.

13. SURFACE_TANGENT_VECTOR_C4        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Vector from center of target planet through tangent line (a radial line 
which intersects the boresight look direction at a 90 deg. angle) to the 
planet surface, with a magnitude equal to the planet radius, UVVS Corner 4. 
In target body-fixed coordinate system. Unit = kilometers. PER STEP column.

*Note: Value = MISSING_CONSTANT when pointing vector is >50 planetary radii 
from planet.

14. RA_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

Right ascension of UVVS footprint center, and 4 corners - 5 total values. 
Format: (center, corner 1, corner 2, corner 3, corner 4). Unit = degrees. 
PER STEP column.

15. DEC_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

Declination of UVVS footprint center, and 4 corners - 5 total values. 
Format: (center, corner 1, corner 2, corner 3, corner 4). Unit =degrees. 
PER STEP column.

16. TARGET_LATITUDE_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

For exosphere observations, this indicates the latitudes below the tangent 
points of the UVVS field-of-view center and corners. For surface 
observations, this indicates the latitudes at the locations where the 
field-of-view center and corners intersect the planet surface. Format: 
(center, corner 1, corner 2, corner 3, corner 4). Unit = degrees. PER STEP 
column.

17. TARGET_LONGITUDE_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

For exosphere observations, this indicates the longitudes below the tangent 
points of the UVVS field-of-view center and corners. For surface 
observations, this indicates the longitudes at the locations where the 
field-of-view center and corners intersect the planet surface. Format: 
(center, corner 1, corner 2, corner 3, corner 4).  Unit = degrees. PER STEP 
column.

18. TARGET_ALTITUDE_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

For exosphere observations, this indicates the altitudes of the actual 
field-of-view center and corner tangent points above the surface along a 
radial line.  For surface observations, these altitudes have a value of 0. 
Format: (center, corner 1, corner 2, corner 3, corner 4). 
Unit = kilometers. PER STEP column.

19. SLIT_ROTATION_ANGLE        
Bytes: 8        Type: IEEE_REAL

Angle of long dimension of the slit with the surface tangent line. 
Unit = degrees. PER STEP column.

20. ALONG_TRACK_FOOTPRINT_SIZE        
Bytes: 8        Type: IEEE_REAL

Derived length of UVVS footprint along track, accounting for smear across 
surface. Unit = meters. PER STEP column.

21. ACROSS_TRACK_FOOTPRINT_SIZE        
Bytes: 8        Type: IEEE_REAL

Derived width of UVVS footprint across track, accounting for jitter across 
surface. Unit = meters. PER STEP column.

22. FOOTPRINT_AZIMUTH        
Bytes: 8        Type: IEEE_REAL

Derived angle of footprint smear relative to a N-S line. 0 is North, 
plus/minus 180 is South, sign denotes east (clockwise) or west rotation of 
azimuth from North. Unit = degrees. PER STEP column.

23. INCIDENCE_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived solar incidence angle of footprint center. Unit = degrees. PER STEP 
column.

24. EMISSION_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived emission angle of footprint center. Unit = degrees. PER STEP column.

25. PHASE_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived phase angle of footprint center. Unit = degrees. PER STEP column.

26. SLANT_RANGE_TO_CENTER        
Bytes: 8        Type: IEEE_REAL

Derived slant range from s/c to footprint center (equal to s/c 
NADIR_ALTITUDE in nadir pointing case). Unit = kilometers. PER STEP column.

27. SUBSPACECRAFT_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft latitude on planet surface. Unit = degrees. PER STEP 
column.

28. SUBSPACECRAFT_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft longitude on planet surface. Unit = degrees. PER STEP 
column.

29. NADIR_ALTITUDE        
Bytes: 8        Type: IEEE_REAL

Derived spacecraft altitude above nadir point. Unit = kilometers. PER STEP 
column.

30. SUBSOLAR_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar latitude on planet surface. Unit = degrees. PER STEP column.

31. SUBSOLAR_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar longitude on planet surface. Unit = degrees. PER STEP 
column.

32. SOLAR_DISTANCE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar distance to footprint center on planet surface.  
Unit = kilometers. PER STEP column.

33. PLANET_TRUE_ANOMALY        
Bytes: 8        Type: IEEE_REAL

Derived true anomaly of planet. Unit = degrees. PER STEP column.

34. MIDSTEP_TIME
Bytes: 8        Type: IEEE_REAL

A calculated value indicating the mission elapsed time since launch at the
middle of an individual UVVS step. Unit = seconds. This is a double 
precision value.

The formula used is:
MIDSTEP_TIME = (N-1)*(INT_TIME+STEP_TIME)/3000 + SC_TIME + 
PACKET_SUBSECONDS*5/1000 + (INT_TIME/3000)/2, 

where N is the Nth step in an observation sequence, and the other values 
are contained in the UVVS Science Header CDR. PER STEP column. 

35. STEP_UTC_TIME        
Bytes: 17       Type: CHARACTER

UTC time in YYDOYTHH:MM:SS.00 format derived from the MIDSTEP_TIME using 
SPICE kernels. PER STEP column.

36. GRATING_OFFSET        
Bytes: 4        Type: IEEE_REAL

Number of grating steps offset from nominal as noted in the 
GRATING_OFFSET.TAB file. A correction for this was implemented in PDS 
delivery 16. PER STEP column.

37. STEP_POSITION        
Bytes: 4        Type: MSB_INTEGER

Actual grating position calculated by start position + 
(step number * step size) + offset. PER STEP column.

38. STEP_WAVELENGTH        
Bytes: 4        Type: IEEE_REAL

From wavelength equation (Eq. 6.2 in calibration report):

See PDF version of document for equations.

where n is grating step number. Unit = nanometers. PER STEP column.

39. RAW_STEP_DATA        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Column of uncompressed raw data. Unit = counts. PER STEP column.

40. COUNT_RATE        
Bytes: 4        Type: IEEE_REAL

Count rate of step. Unit = counts/second. PER STEP column.

41. DEAD_CORRECTED_COUNT_RATE        
Bytes: 4        Type: IEEE_REAL

Count rate corrected for nonlinearity due to dead-time. 
Unit = counts/second. PER STEP column.

42. DARK_RATE       
Bytes: 4        Type: IEEE_REAL

Dark count rate at step from model/module. Unit = counts/second. PER STEP 
column.

43. SCATTERED_LIGHT_RATE        
Bytes: 4        Type: IEEE_REAL

Scattered light at step from model/module. Unit = counts/second. PER STEP 
column.

44. FULLY_CORRECTED_COUNT_RATE        
Bytes: 4        Type: IEEE_REAL

Count rate corrected for dark, scattered light, dead time, etc. 
Unit = counts/second. PER STEP column.

45. FULLY_CORRECTED_COUNT_RATE_UNCERTAINTY        
Bytes: 4        Type: IEEE_REAL

Uncertainty for count rate, equivalent to instrument shot noise. 
Unit = counts/second. PER STEP column.

46. STEP_RADIANCE_KR        
Bytes: 4        Type: IEEE_REAL

Calibrated radiance value at step. Unit = kiloRayleighs/nanometer. PER STEP 
column.

47. STEP_RADIANCE_W        
Bytes: 4        Type: IEEE_REAL

Calibrated radiance value at step.  Unit = W/(m^2 steradian micron). PER 
STEP column.

48. STEP_ RADIANCE_SIGNAL_TO_NOISE        
Bytes: 4        Type: IEEE_REAL

Derived signal to noise in fully calibrated radiance, propagated from fully 
corrected count rate uncertainty and sensitivity uncertainty. Unitless 
ratio, applied to radiance. PER STEP column.

49. PMT_TEMPERATURE        
Bytes: 4        Type: IEEE_REAL

Photomultiplier tube (PMT) temperature in degrees C.

50. DATA_QUALITY_INDEX        
Bytes: 21       Type: CHARACTER

21 character index of data quality. Each digit signifies quality factor of 
measurements. PER STEP column.
Format: A-BCDEF-GHIJ-KLM-NOPQ
A: SBOS trip
  0 = no trip
  1 = trip
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
B: Footprint center on planet
  0 = not on planet
  1 = on planet
C: Footprint C1 on planet
  0 = not on planet
  1 = on planet
D: Footprint C2 on planet
  0 = not on planet
  1 = on planet
E: Footprint C3 on planet
  0 = not on planet
  1 = on planet
F: Footprint C4 on planet
  0 = not on planet
  1 = on planet
G: Partial scan (macro cutoff)
  0 = No partial scan.
  1 = Partial scan.
H: Temperature 1 flag for this UVVS detector
  0 = Temperature does not exceed 25 deg C threshold.
  1 = Temperature exceeds 25 deg C threshold but less than 45 deg C 
  threshold.
  2 = Temperature exceeds 45 deg C threshold.
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
I: UVVS noise spike flag
  0 = No noise spike detected.
  1 = Noise spike detected.
J: VIRS operating flag
  0 = VIRS is not scanning during readout.
  1 = VIRS is scanning during readout.
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
K: Buffer overflow flag
  0 = No buffer overflow.
  1 = Buffer overflow.
L: Background subtraction method
  # = Method used
M: Background quality flag (not yet implemented)
  0 = Not yet implemented.
  1 = Inside TBD threshold.
N: SPICE Version Epoch. Indicates what SPICE is used to determine pointing 
fields in CDR. 'Predict' SPICE may change one or more times before settling 
on 'Final' pointing solutions about 2 weeks from data acquisition.
  0 = No SPICE
  1 = Predict
  2 = Actual
O: Bad data identifier for UVVS. Bad data encompass when a Solar Energetic 
Particle event interacts with the instrument causing noisy data that should 
not be used. There are also times when the instrument wavelength fiducial 
misregisters. The data is compromised when these events happen and should 
not be used. 
  0 = Good Data
  1 = Bad Data
P-Q: Spares

51. SC_TIME        
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Spacecraft time in integer seconds that is transmitted to the MESSENGER 
subsystems by the Integrated Electronics Module. This is assigned as the 
start time of the UVVS observation. A UVVS observation is defined as all the 
scan data contained within one UVVS science packet. This is due to the 
highly configurable nature of the instrument, i.e. it can be commanded to 
take multiple scans over multiple wavelengths. Unit is in mission elapsed 
time which is the number of seconds since launch. PER STEP column.

52. OBSERVATION_TYPE       
Bytes: 30       Type: CHARACTER

Describes the type of observation being executed at this MIDSTEP time. PER 
STEP column..

53. SPARE_2        
Bytes: 8        Type: IEEE_REAL

Orbit number is a unique identifier for a given orbit of the MESSENGER 
spacecraft around Mercury. Orbit number is defined as starting at apoherm 
and is calculated using the MIDSTEP_TIME value and appropriate SPICE 
kernels. Orbit numbering does not start until MESSENGER performs the Mercury 
orbit insertion. Until that time the value for orbit number is 0.

6.3.2 Surface DDR Column Descriptions
Each UVVS surface observation (contiguous time period of data acquisition 
with a given sequence) is associated with two DDR data products: a science 
header table (HDR), showing the instrument command parameters for a given 
observation, and a science data table (SCI), showing counts, derived science 
data, and pointing information for each bin of 5 steps of an observation. 
The table columns are described by the format files UVVSHDRD_SUR.FMT, 
UVVSSCID_SUR.FMT (MUV Surface), and UVVSSCID_FUV_SUR.FMT (FUV Surface). The 
following are detailed descriptions of the columns in the UVVS Surface DDR 
binary table objects. "OBSERVATION" columns have the same value for the 
whole DDR - these are parameters such as integration time set during the 
UVVS setup command. "PER BIN" columns have different values for each bin of 
5 steps in the observation. Times associated with individual bins refer to 
the middle of the integration period for that bin. Replicas of the 
UVVSHDRD_SUR.FMT, UVVSSCID_SUR.FMT, and UVVSSCID_FUV_SUR.FMT format files 
can be found in Appendices C-E.

Note: All undefined field values (e.g., tangent altitudes do not exist if 
the line of sight is looking away from the planet) have been replaced with 
MISSING_CONSTANT = -1.E32, and all fields containing this value should be 
considered as undefined or meaningless.

The UVVS+VIRS Combined DDR format is described in a separate specification 
document, UVVS_VIRS_COMBINED_DDR_SPEC.PDF, located in the DOCUMENT directory 
of this volume.

6.3.2.1 Fields in Surface HDR DDR Format File (UVVSHDRD_SUR.FMT)

1. SC_TIME          
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Spacecraft time in integer seconds that is transmitted to the MESSENGER 
subsystems by the Integrated Electronics Module. This is assigned as the 
start time of the UVVS observation. A UVVS observation is defined as all the 
scan data contained within one UVVS science packet. This is due to the 
highly configurable nature of the instrument, i.e. it can be commanded to 
take multiple scans over multiple wavelengths. Unit is in mission elapsed 
time which is the number of seconds since launch. PER OBSERVATION column.

2. PACKET_SUBSECONDS          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

The subsecond time in milliseconds that the telemetry packet was initiated. 
SC_TIME plus PACKET_SUBSECONDS is the spacecraft time of the first 
integration. Values of this field are in units of 5 milliseconds. For 
example, a value of 10 refers to a time of 50 milliseconds. PER OBSERVATION 
column.

3. START_POS          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Start position where grating drive begins a scan. Grating drive step 
position corresponds to a given wavelength being observed by an instrument. 
PER OBSERVATION column.

4. STEP_COUNT          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of steps the grating drive took in a scan. This directly corresponds 
to the range of wavelengths that were observed in one UVVS observation. PER 
OBSERVATION column.

5. INT_TIME          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Integration time in grating drive loop control interrupt periods (nominally 
3000 Hz). For example, the actual integration time in seconds is 
INT_TIME/3000. PER OBSERVATION column.

6. STEP_TIME          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Step time in grating drive loop control interrupt periods (nominally 3000 
Hz). For example, the actual step time in seconds is STEP_TIME/3000. PER 
OBSERVATION column.

7. PHASE_OFFSET          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Phase offset in grating drive loop control interrupt periods.  Phase offset 
between the beginning of grating drive step and the start of a PMT 
integration in units of 0.3 milliseconds.  Default value is 0 (no phase 
offset).  Setting the phase offset to a non-zero value (reserved for 
contingency operations), instructed the software to initiate a step before 
the end of an integration, accounting for latencies in the motor controller. 
PER OBSERVATION column.

8. SCAN_CYCLES          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of times to repeat scan. PER OBSERVATION column.

9. ZIGZAG          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether grating drive moves in a 'triangle' (stepping up, then 
stepping down), or 'sawtooth' (stepping up, then 'flying' down) motion. A 
'triangle' observation takes one grating scan stepping up the grating, then 
reverses direction and takes the next grating scan stepping back down the 
grating. Scans in opposite directions are offset from one another by two 
grating step positions such that the wavelength ranges are slightly 
different. A 'sawtooth' observation takes one grating scan stepping up the 
grating, then 'flies' the grating back to the START_POSITION to take the 
next observation. =0 disable, =1 enable. PER OBSERVATION column.

10. COMPRESSION          
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Selectable data size, =0 16 bit data, =1 9 bit data. Used to help determine 
the total number of data points contained in the observation. PER 
OBSERVATION column.

11. SLIT_MASK_POS        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether slit mask is in atmospheric (open) or surface (closed) 
position. Atmospheric slit results in a 1 deg. by 0.04 deg. instantaneous 
field of view (iFOV). Surface slit results in a 0.05 deg. by 0.04 deg. iFOV. 
=0 closed, =1 open. PER OBSERVATION column.

12. GD_SETTLE_CTR        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of times during integration that the grating drive wandered outside 
target range. This can happen very rarely with an encoder misread, or motor 
misstep, and would result in an offset of step-number to wavelength 
correlations for subsequent observations in a given scan. PER OBSERVATION 
column.

13. NUM_SCAN_VALUES        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Total number of values or data points in the entire scan observation. Used
to determine the number of valid data points in the SCAN_DATA column. 
Maximum value is 3626. PER OBSERVATION column.

14. STEP_SIZE        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Step size in arcmin units. PER OBSERVATION column.

15. COADD        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Number of steps coadded to make a single observation. Default = 1, i.e. one 
step per observation. PER OBSERVATION column.

16. CALIBRATION_SOFTWARE_VERSION        
Bytes: 4        Type: IEEE_REAL

Indicates version of calibration software used. Increments with reprocessing 
of CDRs. PER OBSERVATION column.

6.3.2.2 Fields in MUV Surface SCI DDR Format File (UVVSSCID_SUR.FMT)
As a single UVVS surface spectrum is acquired by holding the FOV on the 
surface for the duration of a grating scan, Footprint center stability is 
noted in DQI column "O" to denote how much smear across the ground occurs 
during any single observation. 

1. BIN_NUMBER        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

BIN of steps in the observation.

2. TARGET_LATITUDE_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

This indicates the BIN-average latitudes at the locations where the 
field-of-view center and corners intersect the planet   surface. Format: 
(center, corner 1, corner 2, corner 3, corner 4).  Unit = degrees.

3. TARGET_LONGITUDE_SET        
Bytes: 40       Type: IEEE_REAL
Items: 5        Item Bytes: 8

This indicates the BIN-average longitudes at the locations where the 
field-of-view center and corners intersect the planet  surface. Format: 
(center, corner 1, corner 2, corner 3, corner 4).  Unit = degrees.

4. SLIT_ROTATION_ANGLE        
Bytes: 8        Type: IEEE_REAL

BIN average angle of long dimension of the slit with the surface tangent 
line. Unit = degrees.

5. ALONG_TRACK_FOOTPRINT_SIZE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average length of UVVS footprints along track, accounting for 
smear across surface. Unit = meters.
    
6. ACROSS_TRACK_FOOTPRINT_SIZE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average length of UVVS footprints across track, accounting for 
smear across surface. Unit = meters.

7. INCIDENCE_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average solar incidence angle of footprint center. 
Unit = degrees.

8. EMISSION_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average solar emission angle of footprint center. Unit = degrees.

9. PHASE_ANGLE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average solar phase angle of footprint center. Unit = degrees.

10. SOLAR_DISTANCE        
Bytes: 8        Type: IEEE_REAL

Derived BIN average subsolar distance to footprint center on planet surface. 
Unit = kilometers.

11. MIDBIN_TIME
Bytes: 8        Type: IEEE_REAL

A calculated value indicating the average mission elapsed time since launch 
of the BIN of steps. Unit = seconds. This is a double precision value. The 
formula used is:  MIDBIN_TIME = average(MIDSTEP_TIME for each step).   
MIDSTEP_TIME values are taken from the source UVVS Science CDR steps that 
were incorporated into the BIN.

12. BIN_UTC_TIME        
Bytes: 17       Type: CHARACTER

UTC time in YYDOYTHH:MM:SS.00 format in the middle of the BIN of steps.

13. BIN_WAVELENGTH        
Bytes: 4        Type: IEEE_REAL

Center wavelength of BIN, Derived from average step wavelengths from 
wavelength equation. Unit = nanometers..

14. IOF_BIN_DATA        
Bytes: 4        Type: IEEE_REAL

Derived column of BIN reflectance at sensor.

15. PHOTOM_IOF_BIN_DATA        
Bytes: 4        Type: IEEE_REAL

Derived column of BIN photometrically-corrected reflectance at sensor.

16. IOF_BIN_NOISE_DATA        
Bytes: 4        Type: IEEE_REAL

Derived column of BIN reflectance noise/error propagated through 
post-calibration procedure.  PER BIN column.

17. PHOTOM_IOF_BIN_NOISE_DATA        
Bytes: 4        Type: IEEE_REAL

Derived column of BIN photometrically corrected reflectance noise/error 
propagated through post-calibration procedure.

18. FULLY_CORRECTED_COUNT_RATE        
Bytes: 4        Type: IEEE_REAL

Count rate of BIN. Unit = counts/second.

19. BIN_RADIANCE_W        
Bytes: 4        Type: IEEE_REAL

BIN average calibrated radiance value.  Unit = W/(m^2 steradian micron).

20. PMT_TEMPERATURE        
Bytes: 4        Type: IEEE_REAL

BIN average PMT temperature in degrees C.

21. DATA_QUALITY_INDEX        
Bytes: 21       Type: CHARACTER

21 character index of data quality taken from the middle of the BIN of 
steps. Each digit signifies quality factor of measurements. Format: 
A-BCDEF-GHIJ-KLM-NOPQ
A: SBOS trip
  0 = no trip
  1 = trip
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
B: Footprint center on planet
  0 = not on planet
  1 = on planet
C: Footprint C1 on planet
  0 = not on planet
  1 = on planet
D: Footprint C2 on planet
  0 = not on planet
  1 = on planet
E: Footprint C3 on planet
  0 = not on planet
  1 = on planet
F: Footprint C4 on planet
  0 = not on planet
  1 = on planet
G: Partial scan (macro cutoff)
  0 = No partial scan.
  1 = Partial scan.
H: Temperature 1 flag for this UVVS detector
  0 = Temperature does not exceed 25 deg C threshold.
  1 = Temperature exceeds 25 deg C threshold but less than 45 deg C 
  threshold.
  2 = Temperature exceeds 45 deg C threshold.
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
I: UVVS noise spike flag
  0 = No noise spike detected.
  1 = Noise spike detected.
J: VIRS operating flag
  0 = VIRS is not scanning during readout.
  1 = VIRS is scanning during readout.
  9 = Unknown. No information found from MASCS HK EDR for the time period 
  START_TIME to STOP TIME.
K: Buffer overflow flag
  0 = No buffer overflow.
  1 = Buffer overflow.
L: Background subtraction method
  # = Method used
M: Background quality flag (not yet implemented)
  0 = Not yet implemented.
  1 = Inside TBD threshold.
N: SPICE Version Epoch. Indicates what SPICE is used to determine pointing 
fields in CDR. 'Predict' SPICE may change one or more times before settling 
on 'Final' pointing solutions about 2 weeks from data acquisition.
  0 = No SPICE
  1 = Predict
  2 = Actual
O: Footprint center stability. Fraction of FOV smear during the BIN 
observation. 0-9 = 0.0 to 0.9 FOVs movement while obtaining the steps that 
comprise the BIN. A= 1.0 FOVs, B=1.1, C=1.2, etc. each letter representing 
0.1 FOV increments. Z=2.6 or greater FOV's smear.
P-Q: Spares.

22. OBSERVATION_TYPE       
Bytes: 30       Type: CHARACTER

Describes the type of observation being executed at this MIDSTEP time. PER 
STEP column.

23. SPARE       
Bytes: 8        Type: IEEE_REAL

24. SPARE
Bytes: 8        Type: IEEE_REAL

25. SPARE       
Bytes: 8        Type: IEEE_REAL

6.3.2.3 Fields in FUV Surface SCI DDR Format File (UVVSSCID_FUV_SUR.FMT)

The FUV Surface fields are the same as the MUV Surface fields with the 
addition of 1 column, BIN_SOLAR_IRRADIANCE_W.

23. BIN_SOLAR_IRRADIANCE_W       
Bytes: 4        Type: IEEE_REAL

BIN average solar irradiance at Mercury orbital distance. Unit = W/(m^2 
steradian micron). 

24. SPARE       
Bytes: 8        Type: IEEE_REAL

25. SPARE
Bytes: 8        Type: IEEE_REAL

26. SPARE       
Bytes: 8        Type: IEEE_REAL

6.3.3 Atmosphere DDR Column Descriptions
The UVVS observations (contiguous time period of data acquisition with a 
given sequence) are associated with a single Atmosphere DDR data product: 
a science data table (SCI), showing calibrated spectra, total radiance 
integrated over the emission lines, and pointing information for each 
altitude step of a given observational sequence. The table columns are 
described by the format file UVVSSCID.FMT. The following are detailed 
descriptions of the columns in the UVVS Atmosphere DDR binary table objects. 
Each of N time-ordered records in the file represents the observed spectrum 
and radiance at a single altitude. Times and geometry associated with each 
individual record refer to the midpoint of the spectral scan (middle 
wavelength), where the given emission line is centered. A replica of the 
UVVSSCID.FMT format file can be found in Appendix F. 

Note: All undefined field values (e.g., tangent altitudes do not exist if 
the line of sight is looking away from the planet) have been replaced with 
MISSING_CONSTANT = -1.E32, and all fields containing this value should be 
considered as undefined or meaningless.

6.3.2.1 Fields in Atmosphere DDR Format File (UVVSSCID.FMT)

All "PER SPECTRAL SCAN" geometry and time columns are defined at the 
midpoint (middle wavelength) of the observed spectral scan.

1. OBSERVATION_TYPE        
Bytes: 30       Type: CHARACTER
    
Name of the observation type.  PER SPECTRAL SCAN.

2. CDR_NAME 
Bytes: 27       Type: CHARACTER

Name of the CDR from which the data were extracted. PER SPECTRAL SCAN.

3. OBS_SEQUENCE_INDEX
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Counting index for a given observational sequence.  Sequences are arranged 
consecutively in time, so this index allows the points within a given 
sequence to be identified. Resets to 1 with each new sequence. PER SPECTRAL 
SCAN.

4. PLANET_SUN_VECTOR_TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet-sun position in target 
body-fixed coordinate system at midpoint of spectral scan. 
Unit = kilometers. PER SPECTRAL SCAN. 

5. PLANET_SC_VECTOR_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet-spacecraft position in 
target body-fixed coordinate system at midpoint of spectral scan. 
Unit = kilometers. PER SPECTRAL SCAN.

6. BORESIGHT_UNIT_VECTOR_CENTER_ TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS center in target 
body-fixed coordinate system at midpoint of spectral scan. Unit = N/A. PER 
SPECTRAL SCAN.

7. TARGET_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Latitude below the tangent point of the UVVS field-of-view center.  Measured 
at midpoint of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

8. TARGET_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Longitude below the tangent point of the UVVS field-of-view center. Measured 
at midpoint of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

9. TARGET_ALTITUDE 
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Altitude (center, min, max) of the actual field-of-view slit projection.  
Measured at midpoint of spectral scan. Unit = kilometers. PER SPECTRAL SCAN.

10. TARGET_LOCAL_TIME
Bytes: 4        Type: IEEE_REAL

Local time of the tangent point of the UVVS field-of-view center.  Local 
time is defined as 0 at midnight, 6 at dawn, and 12 at noon.  Measured at 
midpoint of spectral scan.  Unit= hour plus fraction of hour. 
(e.g. 1.5 = 90 minutes).  PER SPECTRAL SCAN.

11. SUBSPACECRAFT_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft latitude on planet surface. Measured at midpoint of 
spectral scan. Unit = degrees. PER SPECTRAL SCAN.

12. SUBSPACECRAFT_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft longitude on planet surface. Measured at midpoint of 
spectral scan.  Unit = degrees. PER SPECTRAL SCAN.

13. SPACECRAFT_ALTITUDE        
Bytes: 8        Type: IEEE_REAL

Derived spacecraft altitude above nadir point. Unit = kilometers. PER 
SPECTRAL SCAN.

14. SPACECRAFT_LOCAL_TIME
Bytes: 4        Type: IEEE_REAL

Local time of the subspacecraft point.  Local time is defined as 0 at 
midnight, 6 at dawn, and 12 at noon.  Measured at midpoint of spectral 
scan. Unit=hour plus fraction of hour. (e.g. 1.5 = 90 minutes). PER 
SPECTRAL SCAN.

15. SUBSOLAR_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar latitude on planet surface. Measured at midpoint of 
spectral scan.  Unit = degrees. PER SPECTRAL SCAN.

16. SUBSOLAR_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar longitude on planet surface. Measured at midpoint of 
spectral scan.  Unit = degrees. PER SPECTRAL SCAN.

17. PLANET_TRUE_ANOMALY        
Bytes: 8        Type: IEEE_REAL

Derived true anomaly of planet. Measured at midpoint of spectral scan.  
Unit = degrees. PER SPECTRAL SCAN.

18. ORBIT_NUMBER
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Mercury orbit number. PER SPECTRAL SCAN.

19. MID_SPECTRUM_TIME
Bytes: 8        Type: IEEE_REAL

A calculated value indicating the mission elapsed time since launch at the 
middle of an individual UVVS spectral scan. Unit = seconds. PER SPECTRAL 
SCAN.

20. UTC_TIME        
Bytes: 17       Type: CHARACTER

UTC time in YYDOYTHH:MM:SS.00 format derived from the MID_SPECTRUM_TIME 
using SPICE kernels. PER SPECTRAL SCAN.

21. WAVELENGTH        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Wavelength vector of the spectral scan, which can be up to 25 elements.  
Shorter scans are padded with zeros.  PER SPECTRAL SCAN.

22. RADIANCE_KR        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Vector of calibrated radiances matched with scan WAVELENGTH; up to 25 
elements.  Shorter scans are padded with zeros. 
Unit = kiloRayleighs/nanometer. PER SPECTRAL SCAN.

23. RADIANCE_SNR        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Vector of calibrated radiance SNR matched with scan WAVELENGTH; up to 25 
elements.  Shorter scans are padded with zeros. Derived signal-to-noise in 
fully calibrated radiance, propagated from fully corrected count rate 
uncertainty and sensitivity uncertainty. Unitless fraction, applied to 
radiance. PER SPECTRAL SCAN.

24. TOTAL_RADIANCE_KR        
Bytes: 8        Type: IEEE_REAL

Total radiance integrated over the specified emission line(s) in the given 
calibrated spectrum. Unit = kiloRayleighs. PER SPECTRAL SCAN.

25. TOTAL_RADIANCE_SNR        
Bytes: 8        Type: IEEE_REAL

Derived SNR in the total radiance, propagated from radiance SNR. Unitless 
fraction, applied to total radiance. PER SPECTRAL SCAN.

26. SLIT_POS
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether slit mask is in atmospheric or surface position. 
Atmospheric slit results in a 1 deg. by 0.04 deg. instantaneous field of 
view (iFOV). Surface slit results in a 0.05 deg. by 0.04 deg. iFOV. 
Surface=0, Atmosphere=1.  Unitless, PER SPECTRAL SCAN.

27. SPARE_1        
Bytes: 8        Type: IEEE_REAL

SPARE column.

28. SPARE_2        
Bytes: 8        Type: IEEE_REAL

SPARE column.

29. SPARE_3        
Bytes: 8        Type: IEEE_REAL

SPARE column.

30. SPARE_4        
Bytes: 8        Type: IEEE_REAL

SPARE column.

6.3.4 Atmosphere Summary DDR Column Descriptions (UVVSSUMD.FMT)

Note: All undefined field values (e.g., tangent altitudes do not exist if 
the line of sight is looking away from the planet) have been replaced with 
MISSING_CONSTANT = -1.E32, and all fields containing this value should be 
considered as undefined or meaningless.

All "PER SPECTRAL SCAN" geometry and time columns are defined at the 
midpoint (middle wavelength) of the observed spectral scan.

1. OBSERVATION_TYPE        
Bytes: 30       Type: CHARACTER
    
Name of the observation type. PER SPECTRAL SCAN.

2. CDR_NAME        
Bytes: 27       Type: CHARACTER
    
Name of the CDR from which the data were extracted. PER SPECTRAL SCAN.

3. PLANET_SUN_VECTOR_TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet-sun position in target 
body-fixed coordinate system at midpoint of scan. Unit = kilometers. PER 
SPECTRAL SCAN.

4. PLANET_SC_VECTOR_TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving center-to-center planet-spacecraft position in 
target body-fixed coordinate system at midpoint of scan. Unit = kilometers. 
PER SPECTRAL SCAN.

5. BORESIGHT_UNIT_VECTOR_CENTER_TG        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Derived (x,y,z) vector giving look direction of MASCS UVVS center in target 
body-fixed coordinate system at midpoint of spectral scan. Unit = N/A. PER 
SPECTRAL SCAN.

6. TARGET_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Latitude below the tangent point of the UVVS field-of-view center. Measured 
at midpoint of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

7. TARGET_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Longitude below the tangent point of the UVVS field-of-view center. Measured 
at midpoint of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

8. TARGET_ALTITUDE        
Bytes: 24       Type: IEEE_REAL
Items: 3        Item Bytes: 8

Altitude (center, min, max) of the actual field-of-view slit projection. 
Measured at midpoint of spectral scan. Unit = kilometers. PER SPECTRAL SCAN.

9. TARGET_LOCAL_TIME        
Bytes: 4        Type: IEEE_REAL

Local time of the tangent point of the UVVS field-of-view center. Local time 
is defined as 0 at midnight, 6 at dawn, and 12 at noon. Measured at midpoint 
of spectral scan. Unit= hour plus fraction of hour. (e.g. 1.5 = 90 minutes). 
PER SPECTRAL SCAN.

10. SUBSPACECRAFT_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft latitude on planet surface. Measured at the midpoint 
of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

11. SUBSPACECRAFT_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subspacecraft longitude on planet surface. Measured at the midpoint 
of spectral scan. Unit = degrees. PER SPECTRAL SCAN.

12. SPACECRAFT_ALTITUDE        
Bytes: 8        Type: IEEE_REAL

Derived spacecraft altitude above nadir point. Unit = kilometers. PER 
SPECTRAL SCAN.

13. SPACECRAFT_LOCAL_TIME        
Bytes: 4        Type: IEEE_REAL

Local time of the subspacecraft point. Local time is defined as 0 at 
midnight, 6 at dawn, and 12 at noon. Measured at midpoint of spectral scan. 
Unit= hour plus fraction of hour. (e.g. 1.5 = 90 minutes). PER SPECTRAL SCAN.

14. SUBSOLAR_LATITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar latitude on planet surface. Measured at midpoint of 
spectral scan. Unit = degrees. PER SPECTRAL SCAN.

15. SUBSOLAR_LONGITUDE        
Bytes: 8        Type: IEEE_REAL

Derived subsolar longitude on planet surface. Measured at midpoint of 
spectral scan. Unit = degrees. PER SPECTRAL SCAN.

16. PLANET_TRUE_ANOMALY        
Bytes: 8        Type: IEEE_REAL

Derived true anomaly of planet. Measured at midpoint of spectral scan. 
Unit = degrees. PER SPECTRAL SCAN.

17. ORBIT_NUMBER        
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Mercury orbit number. PER SPECTRAL SCAN.

18. MET_PARTITION        
Bytes: 4        Type: MSB_UNSIGNED_INTEGER

Spacecraft clock partition number used in conjunction with MET value to 
perform time conversion using SPICE kernels. Introduced due to the MET 
rollover on 2013-01-08 which reset the MET value to 1000.

19. MID_SPECTRUM_TIME        
Bytes: 8        Type: IEEE_REAL

A calculated value indicating the mission elapsed time since launch at the 
middle of an individual UVVS spectral scan. Unit = seconds. PER SPECTRAL 
SCAN.

20. UTC_TIME        
Bytes: 17       Type: CHARACTER

UTC time in YYDOYTHH:MM:SS.00 format derived from the MID_SPECTRUM_TIME 
using SPICE kernels. PER SPECTRAL SCAN.

21. WAVELENGTH        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Wavelength vector of the spectral scan, which can be up to 25 elements. 
Shorter scans are padded with zeros. PER SPECTRAL SCAN.

22. RADIANCE_KR        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Vector of calibrated radiances matched with scan WAVELENGTH; up to 25 
elements. Shorter scans are padded with zeros. 
Unit = kiloRayleighs/nanometer. PER SPECTRAL SCAN.

23. RADIANCE_SNR        
Bytes: 200      Type: IEEE_REAL
Items: 25       Item Bytes: 8

Vector of calibrated radiance SNR matched with scan WAVELENGTH; up to 25 
elements. Shorter scans are padded with zeros. Derived signal-to-noise in 
fully calibrated radiance, propagated from fully corrected count rate 
uncertainty and sensitivity uncertainty. Unitless fraction, applied to 
radiance. PER SPECTRAL SCAN.

24. TOTAL_RADIANCE_KR        
Bytes: 8        Type: IEEE_REAL

Total radiance integrated over the specified emission line(s) in the given 
calibrated spectrum. Unit = kiloRayleighs. PER SPECTRAL SCAN.

25. TOTAL_RADIANCE_SNR        
Bytes: 8        Type: IEEE_REAL

Derived SNR in the total radiance, propagated from radiance SNR. Unitless 
fraction, applied to total radiance. PER SPECTRAL SCAN.

26. SLIT_POS        
Bytes: 2        Type: MSB_UNSIGNED_INTEGER

Indicates whether slit mask is in atmospheric or surface position. 
Atmospheric slit results in a 1 deg. by 0.04 deg. instantaneous field of 
view (iFOV). Surface slit results in a 0.05 deg. by 0.04 deg. iFOV. 
Surface=0, Atmosphere=1.  Unitless, PER SPECTRAL SCAN.

27. SPARE_1        
Bytes: 8        Type: IEEE_REAL

SPARE column.

28. SPARE_2        
Bytes: 8        Type: IEEE_REAL

SPARE column.

29. SPARE_3        
Bytes: 8        Type: IEEE_REAL

SPARE column.

30. SPARE_4        
Bytes: 8        Type: IEEE_REAL

SPARE column.

6.3.5 Atmospheric Model DDR Column Descriptions

1. TRUE_ANOMALY        
Bytes: 7        Type: ASCII_REAL
    
Mercury's orbital position in degrees. Fit parameters are provided as 
averages over 5 degree increments, the middle of that 5 degree increment is 
listed in the file (e.g., 2.5 degrees for the 0-5 degree bin).

2. LOCAL_TIME 
Bytes: 6        Type: ASCII_REAL

The local time of the model fit. Only limb scans taken within half an hour 
of the given local time are included in the average.

3. NEAR_SURFACE_DENSITY
Bytes: 15       Type: ASCII_REAL

Average near-surface density from modified Chamberlain model fits. A value 
of -1 indicates no model fit for this combination of TRUE_ANOMALY and 
LOCAL_TIME. Units of cm-3.

4. NEAR_SURFACE_DENSITY_UNCERTAINTY        
Bytes: 15       Type: ASCII_REAL

Average one-sigma standard deviation of the fit to near-surface density. A 
value of -1 indicates no model fit for this combination of TRUE_ANOMALY and 
LOCAL_TIME.  Units of cm-3.

5. TEMPERATURE        
Bytes: 15       Type: ASCII_REAL

Average temperature modified from Chamberlain model fits. A value of -1 
indicates no model fit for this combination of TRUE_ANOMALY and LOCAL_TIME.  
Units of K.

6. TEMPERATURE_UNCERTAINTY        
Bytes: 15       Type: ASCII_REAL

Average one-sigma standard deviation of the fit to temperature. A value of 
-1 indicates no model fit for this combination of TRUE_ANOMALY and 
LOCAL_TIME.  Units of K.

7. SCALE_HEIGHT        
Bytes: 15       Type: ASCII_REAL

Scale height corresponding to the model fit.  A value of -1 indicates no 
model fit for this combination of TRUE_ANOMALY and LOCAL_TIME. Units of km.

8. SPARE_1        
Bytes: 15       Type: ASCII_REAL

Spare column, placeholder for future parameter. Default to spare value of 
0.000000.

9. SPARE_2 
Bytes: 15       Type: ASCII_REAL

Spare column, placeholder for future parameter. Default to spare value of 
0.000000.



7. Appendices

APPENDIX A- UVVSHDRC.FMT FILE

/* FIELDS OBTAINED FROM EXPERIMENT DATA RECORD (EDR) */

OBJECT        = COLUMN
   NAME           = SEQ_COUNTER
   COLUMN_NUMBER  = 1
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 1
   DESCRIPTION    = "CCSDS packet sequence counter. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SC_TIME
   COLUMN_NUMBER  = 2
   BYTES          = 4
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 3
   DESCRIPTION    = "Spacecraft time in integer seconds that is transmitted
   to the MESSENGER subsystems by the Integrated Electronics Module. This is
   assigned as the start time of the UVVS observation. A UVVS observation is
   defined as all the scan data contained within one UVVS science packet.
   This is due to the highly configurable nature of the instrument, i.e. it
   can be commanded to take multiple scans over multiple wavelengths. Unit is
   in mission elapsed time which is the number of seconds since launch. PER 
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PACKET_SUBSECONDS
   COLUMN_NUMBER  = 3
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 7
   DESCRIPTION    = "The subsecond time in milliseconds that the telemetry
   packet was initiated. SC_TIME plus PACKET_SUBSECONDS is the spacecraft
   time of the first integration. Values of this field are in units of 5
   milliseconds. For example, a value of 10 refers to a time of 50 
   milliseconds. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = START_POS
   COLUMN_NUMBER  = 4
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 9
   DESCRIPTION    = "Start position where grating drive begins a scan. 
   Grating drive step position corresponds to a given wavelength being 
   observed by an instrument. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_COUNT
   COLUMN_NUMBER  = 5
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 11
   DESCRIPTION    = "Number of steps the grating drive will take in a scan.
   This directly corresponds to the range of wavelengths that will be 
   observed in one UVVS observation. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = INT_TIME
   COLUMN_NUMBER  = 6
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 13
   DESCRIPTION    = "Integration time in grating drive loop control
   interrupt periods (nominally 3000 Hz). For example, the actual 
   integration time in seconds is INT_TIME/3000. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_TIME
   COLUMN_NUMBER  = 7
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 15
   DESCRIPTION    = "Step time in grating drive loop control interrupt
   periods (nominally 3000 Hz). For example, the actual step time in 
   seconds is STEP_TIME/3000. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHASE_OFFSET
   COLUMN_NUMBER  = 8
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 17
   DESCRIPTION    = "Phase offset in grating drive loop control interrupt 
   periods. Phase offset between the beginning of grating drive step and 
   the start of a PMT integration in units of 0.3 milliseconds. Default 
   value is 0 (no phase offset).  By setting the phase offset to a 
   non-zero value (reserved for contingency operations), the user will 
   tell the software to initiate a step before the end of an integration, 
   accounting for latencies in the motor controller. PER OBSERVATION 
   column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SCAN_CYCLES
   COLUMN_NUMBER  = 9
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 19
   DESCRIPTION    = "Number of times to repeat scan. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = ZIGZAG
   COLUMN_NUMBER  = 10
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 21
   DESCRIPTION    = "Indicates whether grating drive moves in a 'triangle' 
   (stepping up, then stepping down), or 'sawtooth' (stepping up, then 
   'flying' down) motion. A 'triangle' observation takes one grating scan 
   stepping up the grating, then reverses direction and takes the next       
   grating scan stepping back down the grating. Scans in opposite 
   directions are offset from one another by two grating step positions such 
   that the wavelength ranges are slightly different. A 'sawtooth' 
   observation takes one grating scan stepping up the grating, then 'flies' 
   the grating back to the START_POSITION to take the next observation. 
   =0 disable, =1 enable. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = COMPRESSION
   COLUMN_NUMBER  = 11
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 23
   DESCRIPTION    = "Selectable data size, =0 16 bit data, =1 9 bit data.
   Used to help determine the total number of data points contained
   in the observation. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SLIT_MASK_POS
   COLUMN_NUMBER  = 12
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 25
   DESCRIPTION    = "Indicates whether slit mask is in atmospheric (open) 
   or surface (closed) position. Atmospheric slit results in a 1 deg. by 
   0.04 deg. instantaneous field of view (iFOV). Surface slit results in a 
   0.05 deg. by 0.04 deg. iFOV. =0 closed, =1 open. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = FUV_ON
   COLUMN_NUMBER  = 13
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 27
   DESCRIPTION    = "Indicates whether FUV PMT power is on. A more complete 
   description of this field can be found in the MASCS User's Guide    
   (Applicable Document 6 in UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER 
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = MUV_ON
   COLUMN_NUMBER  = 14
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 29
   DESCRIPTION    = "Indicates whether MUV PMT power is on. A more complete
   description of this field can be found in the MASCS User's Guide 
   (Applicable Document 6 in UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER 
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = VIS_ON
   COLUMN_NUMBER  = 15
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 31
   DESCRIPTION    = "Indicates whether VIS PMT power is on. A more complete 
   description of this field can be found in the MASCS User's Guide    
   (Applicable Document 6 in UVVS_CDR_DDR_SIS.PDF). =0 off, =1 on. PER   
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BUFFER_OVERFLOW
   COLUMN_NUMBER  = 16
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 33
   DESCRIPTION    = "Indicates whether scan programmed overflowed data buffer
   and was therefore truncated. =0 false, =1 true. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE_BITS
   COLUMN_NUMBER  = 17
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 35
   DESCRIPTION    = "A two-byte spare location." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = GD_SETTLE_CTR
   COLUMN_NUMBER  = 18
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 37
   DESCRIPTION    = "Number of times during integration that the grating 
   drive wandered outside target range. This can happen very rarely with an 
   encoder misread, or motor misstep, and would result in an offset of 
   step-number to wavelength correlations for subsequent observations in a 
   given scan. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = NUM_SCAN_VALUES
   COLUMN_NUMBER  = 19
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 39
   DESCRIPTION    = "Total number of values or data points in the entire scan
   observation. Used to determine the number of valid data points in the
   SCAN_DATA column. Maximum value is 3626. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_SIZE
   COLUMN_NUMBER  = 20
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 41
   DESCRIPTION    = "Step size in arcmin units. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PAD_BYTE
   COLUMN_NUMBER  = 21
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 43
   DESCRIPTION    = "A two-byte spare location. PER OBSERVATION column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = COADD
   COLUMN_NUMBER  = 22
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 45
   DESCRIPTION    = "Number of steps coadded to make a single observation. 
   Default = 1, i.e. one step per observation. PER OBSERVATION column."  
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = CALIBRATION_SOFTWARE_VERSION
   COLUMN_NUMBER  = 23
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 47
   DESCRIPTION    = "Indicates version of calibration software used.
   Increments with reprocessing of CDRs. PER OBSERVATION column."
END_OBJECT    = COLUMN


APPENDIX B- UVVSSCIC.FMT FILE

OBJECT        = COLUMN
   NAME             = STEP_NUMBER
   COLUMN_NUMBER    = 1
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 1
   DESCRIPTION    = "Step in the observation. PER STEP column."
END_OBJECT    = COLUMN

/* SPICE DERIVED GEOMETRY VALUES */

OBJECT        = COLUMN
   NAME             = PLANET_SUN_VECTOR_TG
   COLUMN_NUMBER    = 2
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 3
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving center-to-center planet-
   sun position in target body-fixed coordinate system. Unit = kilometers. 
   PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_SC_VECTOR_TG 
   COLUMN_NUMBER    = 3
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 27
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving center-to-center planet-
   spacecraft position in target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_CENTER_TG
   COLUMN_NUMBER    = 4
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 51
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS center in target body-fixed coordinate system. Unit = N/A. PER STEP 
   column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_C1_TG
   COLUMN_NUMBER    = 5
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 75
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS corner 1 in target body-fixed coordinate system. Unit = N/A. PER 
   STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_C2_TG
   COLUMN_NUMBER    = 6
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 99
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS corner 2 in target body-fixed coordinate system. Unit = N/A. PER 
   STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_C3_TG
   COLUMN_NUMBER    = 7
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 123
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS corner 3 in target body-fixed coordinate system. Unit = N/A. PER 
   STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_C4_TG
   COLUMN_NUMBER    = 8
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 147
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS corner 4 in target body-fixed coordinate system. Unit = N/A. PER 
   STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SURFACE_TANGENT_VECTOR_CENTER 
   COLUMN_NUMBER    = 9
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 171
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Vector from center of target planet through tangent 
   line (a radial line which intersects the boresight look direction at a 90 
   deg. angle) to the planet surface, with a magnitude equal to the planet 
   radius, UVVS Center. In target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SURFACE_TANGENT_VECTOR_C1
   COLUMN_NUMBER    = 10
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 195
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Vector from center of target planet through tangent 
   line (a radial line which intersects the boresight look direction at a 90 
   deg. angle) to the planet surface, with a magnitude equal to the planet 
   radius, UVVS Corner 1. In target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SURFACE_TANGENT_VECTOR_C2
   COLUMN_NUMBER    = 11
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 219
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Vector from center of target planet through tangent 
   line (a radial line which intersects the boresight look direction at a 90 
   deg. angle) to the planet surface, with a magnitude equal to the planet 
   radius, UVVS Corner 2. In target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SURFACE_TANGENT_VECTOR_C3
   COLUMN_NUMBER    = 12
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 243
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Vector from center of target planet through tangent 
   line (a radial line which intersects the boresight look direction at a 90 
   deg. angle) to the planet surface, with a magnitude equal to the planet 
   radius, UVVS Corner 3. In target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SURFACE_TANGENT_VECTOR_C4 
   COLUMN_NUMBER    = 13
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 267
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Vector from center of target planet through tangent 
   line (a radial line which intersects the boresight look direction at a 90 
   deg. angle) to the planet surface, with a magnitude equal to the planet 
   radius, UVVS Corner 4. In target body-fixed coordinate system. 
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = RA_SET
   COLUMN_NUMBER    = 14
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 291
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Right ascension of UVVS footprint center, and 4 
   corners - 5 total values. Format: (center, corner 1, corner 2, corner 3, 
   corner 4). Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = DEC_SET
   COLUMN_NUMBER    = 15
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 331
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Declination of UVVS footprint center, and 4 
   corners - 5 total values. Format: (center, corner 1, corner 2, corner 3, 
   corner 4). Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LATITUDE_SET
   COLUMN_NUMBER    = 16
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 371
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "For exosphere observations, this indicates the 
   latitudes below the tangent points of the UVVS field-of-view center and 
   corners. For surface observations, this indicates the latitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4). 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LONGITUDE_SET  
   COLUMN_NUMBER    = 17
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 411
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "For exosphere observations, this indicates the 
   longitudes below the tangent points of the UVVS field-of-view center and 
   corners. For surface observations, this indicates the longitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4).  
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_ALTITUDE_SET
   COLUMN_NUMBER    = 18
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 451
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "For exosphere observations, this indicates the 
   altitudes of the actual field-of-view center and corner tangent points 
   above the surface along a radial line.  For surface observations, these 
   altitudes have a value of 0. Format: (center, corner 1, corner 2, 
   corner 3, corner 4). Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SLIT_ROTATION_ANGLE
   COLUMN_NUMBER    = 19
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 491
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Angle of long dimension of the slit with the surface
   tangent line. Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ALONG_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 20
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 499
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived length of UVVS footprint along track, 
   accounting for smear across surface. Unit = meters. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ACROSS_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 21
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 507
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived width of UVVS footprint across track, 
   accounting for jitter across surface. Unit = meters. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = FOOTPRINT_AZIMUTH
   COLUMN_NUMBER    = 22
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 515
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived angle of footprint smear relative to a N-S 
   line. 0 is North, plus/minus 180 is South, sign denotes east (clockwise) 
   or west rotation of azimuth from North. Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = INCIDENCE_ANGLE
   COLUMN_NUMBER    = 23
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 523
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived solar incidence angle of footprint center. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = EMISSION_ANGLE
   COLUMN_NUMBER    = 24
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 531
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived emission angle of footprint center. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PHASE_ANGLE
   COLUMN_NUMBER    = 25
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 539
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived phase angle of footprint center. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SLANT_RANGE_TO_CENTER
   COLUMN_NUMBER    = 26
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 547
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived slant range from s/c to footprint center (equal 
   to s/c NADIR_ALTITUDE in nadir pointing case). Unit = kilometers. PER 
   STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LATITUDE
   COLUMN_NUMBER    = 27
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 555
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived subspacecraft latitude on planet surface. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LONGITUDE
   COLUMN_NUMBER    = 28
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 563
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived subspacecraft longitude on planet surface. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = NADIR_ALTITUDE
   COLUMN_NUMBER    = 29
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 571
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived spacecraft altitude above nadir point.
   Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LATITUDE
   COLUMN_NUMBER    = 30
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 579
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived subsolar latitude on planet surface.
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LONGITUDE
   COLUMN_NUMBER    = 31
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 587
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived subsolar longitude on planet surface. 
   Unit = degrees. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SOLAR_DISTANCE
   COLUMN_NUMBER    = 32
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 595
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived subsolar distance to footprint center on planet
   surface. Unit = kilometers. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_TRUE_ANOMALY
   COLUMN_NUMBER    = 33
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 603
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived true anomaly of planet. Unit = degrees. 
   PER STEP column."
END_OBJECT    = COLUMN

/* CALIBRATED ITEMS AND ADDITIONAL METADATA */

OBJECT        = COLUMN
   NAME           = MIDSTEP_TIME
   COLUMN_NUMBER  = 34
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 611
   DESCRIPTION    = "A calculated value indicating the mission elapsed
   time since launch at the middle of an individual UVVS step. 
   Unit = seconds. This is a double precision value. The formula used is:
   MIDSTEP_TIME = (N-1)*(INT_TIME+STEP_TIME)/3000 + SC_TIME + 
                   PACKET_SUBSECONDS*5/1000 + (INT_TIME/3000)/2 
   where N is the Nth step in an observation sequence, and the other values
   are contained in the UVVS Science Header CDR. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_UTC_TIME
   COLUMN_NUMBER  = 35
   BYTES          = 17
   DATA_TYPE      = CHARACTER
   START_BYTE     = 619
   DESCRIPTION    = "UTC time in YYDOYTHH:MM:SS.00 format derived from the
   MIDSTEP_TIME using SPICE kernels. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = GRATING_OFFSET
   COLUMN_NUMBER  = 36
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 636
   DESCRIPTION    = "Number of grating steps offset from nominal as noted in 
   GRATING_OFFSET.TAB, located in the CALIB directory. A correction for this 
   was implemented in PDS delivery 16. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_POSITION
   COLUMN_NUMBER  = 37
   BYTES          = 4
   DATA_TYPE      = MSB_INTEGER
   START_BYTE     = 640
   DESCRIPTION    = "Actual grating position calculated by start position + 
   (step number * step size) + offset. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_WAVELENGTH
   COLUMN_NUMBER  = 38
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 644
   DESCRIPTION    = "From wavelength equation. Unit = nanometers. PER STEP 
   column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = RAW_STEP_DATA
   COLUMN_NUMBER  = 39
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 648
   DESCRIPTION    = "Column of uncompressed raw data. Unit = counts. PER STEP 
   column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = COUNT_RATE
   COLUMN_NUMBER  = 40
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 650
   DESCRIPTION    = "Count rate of step. Unit = counts/second. PER STEP 
   column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = DEAD_CORRECTED_COUNT_RATE
   COLUMN_NUMBER  = 41
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 654
   DESCRIPTION    = "Count rate corrected for nonlinearity due to dead-time.
   Unit = counts/second. PER STEP column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = DARK_RATE
   COLUMN_NUMBER  = 42
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 658
   DESCRIPTION    = "Dark count rate at step from model/module. 
   Unit = counts/second. PER STEP column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SCATTERED_LIGHT_RATE
   COLUMN_NUMBER  = 43
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 662
   DESCRIPTION    = "Scattered light at step from model/module. 
   Unit = counts/second. PER STEP column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = FULLY_CORRECTED_COUNT_RATE
   COLUMN_NUMBER  = 44
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 666
   DESCRIPTION    = "Count rate corrected for dark, scattered light, dead 
   time, etc. Unit = counts/second. PER STEP column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = FULLY_CORRECTED_COUNT_RATE_UNCERTAINTY
   COLUMN_NUMBER  = 45
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 670
   DESCRIPTION    = "Uncertainty for count rate, equivalent to instrument 
   shot noise. Unit = counts/second. PER STEP column." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_RADIANCE_KR
   COLUMN_NUMBER  = 46
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 674
   DESCRIPTION    = "Calibrated radiance value at step. 
   Unit = kiloRayleighs/nanometer. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_RADIANCE_W
   COLUMN_NUMBER  = 47
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 678
   DESCRIPTION    = "Calibrated radiance value at step.  
   Unit = W/(m^2 steradian micron). PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_RADIANCE_SIGNAL_TO_NOISE
   COLUMN_NUMBER  = 48
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 682
   DESCRIPTION    = "Signal to noise ratio for the step radiance values."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PMT_TEMPERATURE
   COLUMN_NUMBER  = 49
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 686
   DESCRIPTION    = "PMT temperature in degrees C."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = DATA_QUALITY_INDEX
   COLUMN_NUMBER  = 50
   BYTES          = 21
   DATA_TYPE      = CHARACTER
   START_BYTE     = 690
   DESCRIPTION    = "21 character index of data quality. Each digit signifies
   quality factor of measurements. PER STEP column.
   Format: A-BCDEF-GHIJ-KLM-NOPQ
   A: SBOS trip
     0 = no trip
     1 = trip
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   B: Footprint center on planet
     0 = not on planet
     1 = on planet
   C: Footprint C1 on planet
     0 = not on planet
     1 = on planet
   D: Footprint C2 on planet
     0 = not on planet
     1 = on planet
   E: Footprint C3 on planet
     0 = not on planet
     1 = on planet
   F: Footprint C4 on planet
     0 = not on planet
     1 = on planet
   G: Partial scan (macro cutoff)
     0 = No partial scan.
     1 = Partial scan.
   H: Temperature 1 flag for this UVVS detector
     0 = Temperature does not exceed 25 deg C threshold.
     1 = Temperature exceeds 25 deg C threshold but less than 45 deg C 
     threshold.
     2 = Temperature exceeds 45 deg C threshold.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   I: UVVS noise spike flag
     0 = No noise spike detected.
     1 = Noise spike detected.
   J: VIRS operating flag
     0 = VIRS is not scanning during readout.
     1 = VIRS is scanning during readout.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   K: Buffer overflow flag
     0 = No buffer overflow.
     1 = Buffer overflow.
   L: Background subtraction method
     # = Method used
   M: Background quality flag (not yet implemented)
     0 = Not yet implemented.
     1 = Inside TBD threshold.
   N: SPICE Version Epoch. Indicates what SPICE is used to determine pointing
     fields in CDR. 'Predict' SPICE may change one or more times before 
     settling on 'Final' pointing solutions about 2 weeks from data
     acquisition.
     0 = No SPICE
     1 = Predict
     2 = Actual
   O: Bad data identifier for UVVS. Bad data encompass when a Solar Energetic
     Particle event interacts with the instrument causing noisy data that
     should not be used. There are also times when the instrument wavelength
     fiducial misregisters. The data is compromised when these events happen
     and should not be used. 
     0 = Good Data
     1 = Bad Data
   P-Q: Spares"
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SC_TIME
   COLUMN_NUMBER  = 51
   BYTES          = 4
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 711
   DESCRIPTION    = "Spacecraft time in integer seconds that is transmitted
   to the MESSENGER subsystems by the Integrated Electronics Module. This is
   assigned as the start time of the UVVS observation. A UVVS observation is
   defined as all the scan data contained within one UVVS science packet.
   This is due to the highly configurable nature of the instrument, i.e. it
   can be commanded to take multiple scans over multiple wavelengths. Unit is
   in mission elapsed time which is the number of seconds since launch. PER 
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = OBSERVATION_TYPE
   COLUMN_NUMBER  = 52
   BYTES          = 30
   DATA_TYPE      = CHARACTER
   START_BYTE     = 715
   DESCRIPTION    = "Describes the type of observation being executed at this
   MIDSTEP time. PER STEP column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = ORBIT_NUMBER
   COLUMN_NUMBER  = 53
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 745
   DESCRIPTION   = "Orbit number is a unique identifier for a given orbit of
    the MESSENGER spacecraft around Mercury. Orbit number is defined as
    starting at apoherm and is calculated using the MIDSTEP_TIME value and
    appropriate SPICE kernels. Orbit numbering does not start until MESSENGER
    performs the Mercury orbit insertion. Until that time the value for orbit
    number is 0."
END_OBJECT    = COLUMN


APPENDIX C- UVVSHDRD_SUR.FMT FILE

/*** ALL VALUES TAKEN DIRECTLY FROM UVVS HEADER CDR ***/

OBJECT        = COLUMN
   NAME           = SC_TIME
   COLUMN_NUMBER  = 1
   BYTES          = 4
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 1
   DESCRIPTION    = "Spacecraft time in integer seconds that is transmitted
   to the MESSENGER subsystems by the Integrated Electronics Module. This is
   assigned as the start time of the UVVS observation. A UVVS observation is
   defined as all the scan data contained within one UVVS science packet.
   This is due to the highly configurable nature of the instrument, i.e. it
   can be commanded to take multiple scans over multiple wavelengths. Unit is
   in mission elapsed time which is the number of seconds since launch. PER 
   OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PACKET_SUBSECONDS
   COLUMN_NUMBER  = 2
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 5
   DESCRIPTION    = "The subsecond time in milliseconds that the telemetry
   packet was initiated. SC_TIME plus PACKET_SUBSECONDS is the spacecraft
   time of the first integration. Values of this field are in units of 5
   milliseconds. For example, a value of 10 refers to a time of 50 
   milliseconds. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = START_POS
   COLUMN_NUMBER  = 3
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 7
   DESCRIPTION    = "Start position where grating drive begins a scan. 
   Grating drive step position corresponds to a given wavelength being 
   observed by an instrument. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_COUNT
   COLUMN_NUMBER  = 4
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 9
   DESCRIPTION    = "Number of steps the grating drive will take in a scan.
   This directly corresponds to the range of wavelengths that will be 
   observed in one UVVS observation. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = INT_TIME
   COLUMN_NUMBER  = 5
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 11
   DESCRIPTION    = "Integration time in grating drive loop control
   interrupt periods (nominally 3000 Hz). For example, the actual 
   integration time in seconds is INT_TIME/3000. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_TIME
   COLUMN_NUMBER  = 6
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 13
   DESCRIPTION    = "Step time in grating drive loop control interrupt
   periods (nominally 3000 Hz). For example, the actual step time in 
   seconds is STEP_TIME/3000. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHASE_OFFSET
   COLUMN_NUMBER  = 7
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 15
   DESCRIPTION    = "Phase offset in grating drive loop control interrupt 
   periods. Phase offset between the beginning of grating drive step and 
   the start of a PMT integration in units of 0.3 milliseconds. Default 
   value is 0 (no phase offset).  By setting the phase offset to a 
   non-zero value (reserved for contingency operations), the user will 
   tell the software to initiate a step before the end of an integration, 
   accounting for latencies in the motor controller. PER OBSERVATION 
   column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SCAN_CYCLES
   COLUMN_NUMBER  = 8
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 17
   DESCRIPTION    = "Number of times to repeat scan. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = ZIGZAG
   COLUMN_NUMBER  = 9
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 19
   DESCRIPTION    = "Indicates whether grating drive moves in a 'triangle' 
   (stepping up, then stepping down), or 'sawtooth' (stepping up, then 
   'flying' down) motion. A 'triangle' observation takes one grating scan 
   stepping up the grating, then reverses direction and takes the next 
   grating scan stepping back down the grating. Scans in opposite directions
   are offset from one another by two grating step positions such that the
   wavelength ranges are slightly different. A 'sawtooth' observation takes 
   one grating scan stepping up the grating, then 'flies' the grating back 
   to the START_POSITION to take the next observation. =0 disable, 
   =1 enable. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = COMPRESSION
   COLUMN_NUMBER  = 10
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 21
   DESCRIPTION    = "Selectable data size, =0 16 bit data, =1 9 bit data.
   Used to help determine the total number of data points contained
   in the observation. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SLIT_MASK_POS
   COLUMN_NUMBER  = 11
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 23
   DESCRIPTION    = "Indicates whether slit mask is in atmospheric (open) 
   or surface (closed) position. Atmospheric slit results in a 1 deg. by 
   0.04 deg. instantaneous field of view (iFOV). Surface slit results in a 
   0.05 deg. by 0.04 deg. iFOV. =0 closed, =1 open. PER OBSERVATION column."
END_OBJECT    = COLUMN


OBJECT        = COLUMN
   NAME           = GD_SETTLE_CTR
   COLUMN_NUMBER  = 12
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 25
   DESCRIPTION    = "Number of times during integration that the grating 
   drive wandered outside target range. This can happen very rarely with an 
   encoder misread, or motor misstep, and would result in an offset of 
   step-number to wavelength correlations for subsequent observations in a 
   given scan. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = NUM_SCAN_VALUES
   COLUMN_NUMBER  = 13
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 27
   DESCRIPTION    = "Total number of values or data points in the entire scan
   observation. Used to determine the number of valid data points in the
   SCAN_DATA column. Maximum value is 3626. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = STEP_SIZE
   COLUMN_NUMBER  = 14
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 29
   DESCRIPTION    = "Step size in arcmin units. PER OBSERVATION column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = COADD
   COLUMN_NUMBER  = 15
   BYTES          = 2
   DATA_TYPE      = MSB_UNSIGNED_INTEGER
   START_BYTE     = 31
   DESCRIPTION    = "Number of steps coadded to make a single observation. 
   Default = 1, i.e. one step per observation. PER OBSERVATION column."  
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = CALIBRATION_SOFTWARE_VERSION
   COLUMN_NUMBER  = 16
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 33
   DESCRIPTION    = "Indicates version of calibration software used to 
   generate UVVS Surface Reflectance Science DDR. Increments with
   reprocessing of DDRs. PER OBSERVATION column."
END_OBJECT    = COLUMN


APPENDIX D- UVVSSCID_SUR.FMT FILE

OBJECT        = COLUMN
   NAME             = BIN_NUMBER
   COLUMN_NUMBER    = 1
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 1
   DESCRIPTION    = "BIN of steps in the observation."
END_OBJECT    = COLUMN

/* SPICE DERIVED GEOMETRY VALUES */

OBJECT        = COLUMN
   NAME             = TARGET_LATITUDE_SET
   COLUMN_NUMBER    = 2
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 3
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "This indicates the BIN-average latitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4). 
   Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LONGITUDE_SET  
   COLUMN_NUMBER    = 3
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 43
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "This indicates the BIN-average longitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4).  
   Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SLIT_ROTATION_ANGLE
   COLUMN_NUMBER    = 4
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 83
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "BIN average angle of long dimension of the slit with the
   surface tangent line. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ALONG_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 5
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 91
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived BIN average length of UVVS footprints along
   track, accounting for smear across surface. Unit = meters."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ACROSS_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 6
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 99
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived BIN width of UVVS footprints across track, 
   accounting for jitter across surface. Unit = meters."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = INCIDENCE_ANGLE
   COLUMN_NUMBER    = 7
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 107
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average solar incidence angle of footprint
   center. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = EMISSION_ANGLE
   COLUMN_NUMBER    = 8
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 115
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average emission angle of footprint
   center. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PHASE_ANGLE
   COLUMN_NUMBER    = 9
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 123
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average phase angle of footprint center. 
   Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SOLAR_DISTANCE
   COLUMN_NUMBER    = 10
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 131
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average subsolar distance to footprint 
   center on planet surface. Unit = kilometers."
END_OBJECT    = COLUMN


/* CALIBRATED ITEMS AND ADDITIONAL METADATA */

OBJECT        = COLUMN
   NAME           = MIDBIN_TIME
   COLUMN_NUMBER  = 11
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 139
   DESCRIPTION    = "A calculated value indicating the average mission 
   elapsed time since launch of the BIN of steps. 
   Unit = seconds. This is a double precision value. The formula used is:
   MIDBIN_TIME = average(MIDSTEP_TIME for each step).
   MIDSTEP_TIME values are taken from the source UVVS Science CDR steps
   that were incorporated into the BIN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_UTC_TIME
   COLUMN_NUMBER  = 12
   BYTES          = 17
   DATA_TYPE      = CHARACTER
   START_BYTE     = 147
   DESCRIPTION    = "UTC time in YYDOYTHH:MM:SS.00 format in the middle of
   the BIN of steps."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_WAVELENGTH
   COLUMN_NUMBER  = 13
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 164
   DESCRIPTION    = "Center wavelength of BIN, Derived from average step 
   wavelengths from wavelength equation. Unit = nanometers."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = IOF_BIN_DATA
   COLUMN_NUMBER  = 14
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 168
   DESCRIPTION    = "Derived column of BIN reflectance at sensor."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHOTOM_IOF_BIN_DATA
   COLUMN_NUMBER  = 15
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 172
   DESCRIPTION    = "Derived column of BIN photometrically corrected
   reflectance at sensor."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = IOF_BIN_NOISE_DATA
   COLUMN_NUMBER  = 16
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 176
   DESCRIPTION    = "Derived column of BIN reflectance noise/error propagated 
   through post-calibration procedure.
   PER BIN column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHOTOM_IOF_BIN_NOISE_DATA
   COLUMN_NUMBER  = 17
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 180
   DESCRIPTION    = "Derived column of BIN photometrically corrected   
   reflectance noise/error propagated through post-calibration procedure." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = FULLY_CORRECTED_COUNT_RATE
   COLUMN_NUMBER  = 18
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 184
   DESCRIPTION    = "Count rate of BIN. Unit = counts/second." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_RADIANCE_W
   COLUMN_NUMBER  = 19
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 188
   DESCRIPTION    = "BIN average calibrated radiance value
   Unit = W/(m^2 steradian micron)." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PMT_TEMPERATURE
   COLUMN_NUMBER  = 20
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 192
   DESCRIPTION    = "BIN average PMT temperature in degrees C."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = DATA_QUALITY_INDEX
   COLUMN_NUMBER  = 21
   BYTES          = 21
   DATA_TYPE      = CHARACTER
   START_BYTE     = 196
   DESCRIPTION    = "21 character index of data quality taken from the middle
   of the BIN of steps. Each digit signifies quality factor of measurements.
   Format: A-BCDEF-GHIJ-KLM-NOPQ
   A: SBOS trip
     0 = no trip
     1 = trip
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   B: Footprint center on planet
     0 = not on planet
     1 = on planet
   C: Footprint C1 on planet
     0 = not on planet
     1 = on planet
   D: Footprint C2 on planet
     0 = not on planet
     1 = on planet
   E: Footprint C3 on planet
     0 = not on planet
     1 = on planet
   F: Footprint C4 on planet
     0 = not on planet
     1 = on planet
   G: Partial scan (macro cutoff)
     0 = No partial scan.
     1 = Partial scan.
   H: Temperature 1 flag for this UVVS detector
     0 = Temperature does not exceed 25 deg C threshold.
     1 = Temperature exceeds 25 deg C threshold but less than 45 deg C 
     threshold.
     2 = Temperature exceeds 45 deg C threshold.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   I: UVVS noise spike flag
     0 = No noise spike detected.
     1 = Noise spike detected.
   J: VIRS operating flag
     0 = VIRS is not scanning during readout.
     1 = VIRS is scanning during readout.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   K: Buffer overflow flag
     0 = No buffer overflow.
     1 = Buffer overflow.
   L: Background subtraction method
     # = Method used
   M: Background quality flag (not yet implemented)
     0 = Not yet implemented.
     1 = Inside TBD threshold.
   N: SPICE Version Epoch. Indicates what SPICE is used to determine pointing
     fields in CDR. 'Predict' SPICE may change one or more times before 
     settling on 'Final' pointing solutions about 2 weeks from data
     acquisition.
     0 = No SPICE
     1 = Predict
     2 = Actual
   O: Footprint center stability. Fraction of FOV smear during the BIN 
     observation. 0-9 = 0.0 to 0.9 FOVs movement while obtaining the steps 
     that comprise the BIN. A= 1.0 FOVs, B=1.1, C=1.2, etc. each letter 
     representing 0.1 FOV increments. Z=2.6 or greater FOV's smear.
   P-Q: Spares"
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = OBSERVATION_TYPE
   COLUMN_NUMBER  = 22
   BYTES          = 30
   DATA_TYPE      = CHARACTER
   START_BYTE     = 217
   DESCRIPTION    = "Describes the type of observation being executed in the
   middle of the BIN of steps."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE
   COLUMN_NUMBER  = 23
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 247
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE_2
   COLUMN_NUMBER  = 24
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 255
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE_3
   COLUMN_NUMBER  = 25
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 263
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN


APPENDIX E- UVVSSCID_FUV_SUR.FMT FILE

OBJECT        = COLUMN
   NAME             = BIN_NUMBER
   COLUMN_NUMBER    = 1
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 1
   DESCRIPTION    = "BIN of steps in the observation."
END_OBJECT    = COLUMN

/* SPICE DERIVED GEOMETRY VALUES */

OBJECT        = COLUMN
   NAME             = TARGET_LATITUDE_SET
   COLUMN_NUMBER    = 2
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 3
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "This indicates the BIN-average latitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4). 
   Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LONGITUDE_SET  
   COLUMN_NUMBER    = 3
   BYTES            = 40
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 43
   ITEMS            = 5
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "This indicates the BIN-average longitudes at the 
   locations where the field-of-view center and corners intersect the planet 
   surface. Format: (center, corner 1, corner 2, corner 3, corner 4).  
   Unit = degrees."
END_OBJECT    = COLUMN


OBJECT        = COLUMN
   NAME             = SLIT_ROTATION_ANGLE
   COLUMN_NUMBER    = 4
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 83
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "BIN average angle of long dimension of the slit with the
   surface tangent line. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ALONG_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 5
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 91
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived BIN average length of UVVS footprints along
   track, accounting for smear across surface. Unit = meters."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ACROSS_TRACK_FOOTPRINT_SIZE
   COLUMN_NUMBER    = 6
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 99
   MISSING_CONSTANT = -1.E32
   DESCRIPTION    = "Derived BIN width of UVVS footprints across track, 
   accounting for jitter across surface. Unit = meters."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = INCIDENCE_ANGLE
   COLUMN_NUMBER    = 7
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 107
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average solar incidence angle of footprint
   center. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = EMISSION_ANGLE
   COLUMN_NUMBER    = 8
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 115
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average emission angle of footprint
   center. Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PHASE_ANGLE
   COLUMN_NUMBER    = 9
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 123
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average phase angle of footprint center. 
   Unit = degrees."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SOLAR_DISTANCE
   COLUMN_NUMBER    = 10
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 131
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived BIN average subsolar distance to footprint 
   center on planet surface. Unit = kilometers."
END_OBJECT    = COLUMN


/* CALIBRATED ITEMS AND ADDITIONAL METADATA */

OBJECT        = COLUMN
   NAME           = MIDBIN_TIME
   COLUMN_NUMBER  = 11
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 139
   DESCRIPTION    = "A calculated value indicating the average mission 
   elapsed time since launch of the BIN of steps. 
   Unit = seconds. This is a double precision value. The formula used is:
   MIDBIN_TIME = average(MIDSTEP_TIME for each step).
   MIDSTEP_TIME values are taken from the source UVVS Science CDR steps
   that were incorporated into the BIN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_UTC_TIME
   COLUMN_NUMBER  = 12
   BYTES          = 17
   DATA_TYPE      = CHARACTER
   START_BYTE     = 147
   DESCRIPTION    = "UTC time in YYDOYTHH:MM:SS.00 format in the middle of
   the BIN of steps."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_WAVELENGTH
   COLUMN_NUMBER  = 13
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 164
   DESCRIPTION    = "Center wavelength of BIN, Derived from average step 
   wavelengths from wavelength equation. Unit = nanometers."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = IOF_BIN_DATA
   COLUMN_NUMBER  = 14
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 168
   DESCRIPTION    = "Derived column of BIN reflectance at sensor."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHOTOM_IOF_BIN_DATA
   COLUMN_NUMBER  = 15
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 172
   DESCRIPTION    = "Derived column of BIN photometrically corrected
   reflectance at sensor."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = IOF_BIN_NOISE_DATA
   COLUMN_NUMBER  = 16
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 176
   DESCRIPTION    = "Derived column of BIN reflectance noise/error propagated 
   through post-calibration procedure.
   PER BIN column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PHOTOM_IOF_BIN_NOISE_DATA
   COLUMN_NUMBER  = 17
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 180
   DESCRIPTION    = "Derived column of BIN photometrically corrected   
   reflectance noise/error propagated through post-calibration procedure." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = FULLY_CORRECTED_COUNT_RATE
   COLUMN_NUMBER  = 18
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 184
   DESCRIPTION    = "Count rate of BIN. Unit = counts/second." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_RADIANCE_W
   COLUMN_NUMBER  = 19
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 188
   DESCRIPTION    = "BIN average calibrated radiance value
   Unit = W/(m^2 steradian micron)." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = PMT_TEMPERATURE
   COLUMN_NUMBER  = 20
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 192
   DESCRIPTION    = "BIN average PMT temperature in degrees C."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = DATA_QUALITY_INDEX
   COLUMN_NUMBER  = 21
   BYTES          = 21
   DATA_TYPE      = CHARACTER
   START_BYTE     = 196
   DESCRIPTION    = "21 character index of data quality taken from the middle
   of the BIN of steps. Each digit signifies quality factor of measurements.
   Format: A-BCDEF-GHIJ-KLM-NOPQ
   A: SBOS trip
     0 = no trip
     1 = trip
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   B: Footprint center on planet
     0 = not on planet
     1 = on planet
   C: Footprint C1 on planet
     0 = not on planet
     1 = on planet
   D: Footprint C2 on planet
     0 = not on planet
     1 = on planet
   E: Footprint C3 on planet
     0 = not on planet
     1 = on planet
   F: Footprint C4 on planet
     0 = not on planet
     1 = on planet
   G: Partial scan (macro cutoff)
     0 = No partial scan.
     1 = Partial scan.
   H: Temperature 1 flag for this UVVS detector
     0 = Temperature does not exceed 25 deg C threshold.
     1 = Temperature exceeds 25 deg C threshold but less than 45 deg C 
     threshold.
     2 = Temperature exceeds 45 deg C threshold.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   I: UVVS noise spike flag
     0 = No noise spike detected.
     1 = Noise spike detected.
   J: VIRS operating flag
     0 = VIRS is not scanning during readout.
     1 = VIRS is scanning during readout.
     9 = Unknown. No information found from MASCS HK EDR for the time period 
         START_TIME to STOP TIME.
   K: Buffer overflow flag
     0 = No buffer overflow.
     1 = Buffer overflow.
   L: Background subtraction method
     # = Method used
   M: Background quality flag (not yet implemented)
     0 = Not yet implemented.
     1 = Inside TBD threshold.
   N: SPICE Version Epoch. Indicates what SPICE is used to determine pointing
     fields in CDR. 'Predict' SPICE may change one or more times before 
     settling on 'Final' pointing solutions about 2 weeks from data
     acquisition.
     0 = No SPICE
     1 = Predict
     2 = Actual
   O: Footprint center stability. Fraction of FOV smear during the BIN 
     observation. 0-9 = 0.0 to 0.9 FOVs movement while obtaining the steps 
     that comprise the BIN. A= 1.0 FOVs, B=1.1, C=1.2, etc. each letter 
     representing 0.1 FOV increments. Z=2.6 or greater FOV's smear.
   P-Q: Spares"
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = OBSERVATION_TYPE
   COLUMN_NUMBER  = 22
   BYTES          = 30
   DATA_TYPE      = CHARACTER
   START_BYTE     = 217
   DESCRIPTION    = "Describes the type of observation being executed in the
   middle of the BIN of steps."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = BIN_SOLAR_IRRADIANCE_W
   COLUMN_NUMBER  = 23
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 247
   DESCRIPTION    = "BIN average solar irradiance at Mercury orbital    
   distance. Unit = W/(m^2 steradian micron)." 
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE
   COLUMN_NUMBER  = 24
   BYTES          = 4
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 251
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE_2
   COLUMN_NUMBER  = 25
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 255
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME           = SPARE_3
   COLUMN_NUMBER  = 26
   BYTES          = 8
   DATA_TYPE      = IEEE_REAL
   START_BYTE     = 263
   DESCRIPTION    = "SPARE column."
END_OBJECT    = COLUMN


APPENDIX F- UVVSSCID.FMT FILE

NOTE = "All 'PER SPECTRAL SCAN' geometry and time columns are defined at the
midpoint (middle wavelength) of the observed spectral scan."

OBJECT        = COLUMN
   NAME             = OBSERVATION_TYPE
   COLUMN_NUMBER    = 1
   BYTES            = 30
   DATA_TYPE        = CHARACTER
   START_BYTE       = 1
   DESCRIPTION      = "Name of the observation type. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = CDR_NAME
   COLUMN_NUMBER    = 2
   BYTES            = 27
   DATA_TYPE        = CHARACTER
   START_BYTE       = 31
   DESCRIPTION      = "Name of the CDR from which the data were extracted.
   PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = OBS_SEQUENCE_INDEX
   COLUMN_NUMBER    = 3
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 58
   DESCRIPTION      = "Counting index for a given observational sequence.
   Sequences are arranged consecutively in time, so this index allows the
   points within a given sequence to be identified. Resets to 1 with each 
   new sequence. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

/* SPICE DERIVED GEOMETRY VALUES */

OBJECT        = COLUMN
   NAME             = PLANET_SUN_VECTOR_TG
   COLUMN_NUMBER    = 4
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 60
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving center-to-center 
   planet-sun position in target body-fixed coordinate system at midpoint of 
   scan. Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_SC_VECTOR_TG 
   COLUMN_NUMBER    = 5
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 84
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving center-to-center 
   planet-spacecraft position in target body-fixed coordinate system at 
   midpoint of scan. Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_CENTER_TG
   COLUMN_NUMBER    = 6
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 108
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS center in target body-fixed coordinate system at midpoint of 
   spectral scan. Unit = N/A. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LATITUDE
   COLUMN_NUMBER    = 7
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 132
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Latitude below the tangent point of the UVVS 
   field-of-view center. Measured at midpoint of spectral scan. 
   Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LONGITUDE  
   COLUMN_NUMBER    = 8
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 140
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Longitude below the tangent point of the UVVS
   field-of-view center. Measured at midpoint of spectral scan. 
   Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_ALTITUDE
   COLUMN_NUMBER    = 9
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 148
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Altitude (center, min, max) of the actual field-of-
   view slit projection. Measured at midpoint of spectral scan. 
   Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LOCAL_TIME
   COLUMN_NUMBER    = 10
   BYTES            = 4
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 172
   DESCRIPTION      = "Local time of the tangent point of the UVVS
   field-of-view center. Local time is defined as 0 at midnight, 6 at dawn,
   and 12 at noon. Measured at midpoint of spectral scan. Unit= hour plus 
   fraction of hour. (e.g. 1.5 = 90 minutes). PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LATITUDE
   COLUMN_NUMBER    = 11
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 176
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subspacecraft latitude on planet surface. 
   Measured at the midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LONGITUDE
   COLUMN_NUMBER    = 12
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 184
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subspacecraft longitude on planet surface. 
   Measured at the midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPACECRAFT_ALTITUDE
   COLUMN_NUMBER    = 13
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 192
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived spacecraft altitude above nadir point.
   Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPACECRAFT_LOCAL_TIME
   COLUMN_NUMBER    = 14
   BYTES            = 4
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 200
   DESCRIPTION      = "Local time of the subspacecraft point. Local time is 
   defined as 0 at midnight, 6 at dawn, and 12 at noon. Measured at midpoint 
   of spectral scan. Unit= hour plus fraction of hour. 
   (e.g. 1.5 = 90 minutes). PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LATITUDE
   COLUMN_NUMBER    = 15
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 204
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subsolar latitude on planet surface.
   Measured at midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LONGITUDE
   COLUMN_NUMBER    = 16
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 212
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subsolar longitude on planet surface. 
   Measured at midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_TRUE_ANOMALY
   COLUMN_NUMBER    = 17
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 220
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived true anomaly of planet. Measured at midpoint 
   of spectral scan. Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ORBIT_NUMBER
   COLUMN_NUMBER    = 18
   BYTES            = 4
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 228
   DESCRIPTION      = "Mercury orbit number. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = MET_PARTITION
   COLUMN_NUMBER    = 19
   BYTES            = 4
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 232
   DESCRIPTION      = "Spacecraft clock partition number used in conjunction
     with MET value to perform time conversion using SPICE kernels. 
     Introduced due to the MET rollover on 2013-01-08 which reset the MET
     value to 1000."
END_OBJECT    = COLUMN

/* CALIBRATED ITEMS AND ADDITIONAL METADATA */

OBJECT        = COLUMN
   NAME             = MID_SPECTRUM_TIME
   COLUMN_NUMBER    = 20
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 236
   DESCRIPTION      = "A calculated value indicating the mission elapsed
   time since launch at the middle of an individual UVVS spectral scan. 
   Unit = seconds. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = UTC_TIME
   COLUMN_NUMBER    = 21
   BYTES            = 17
   DATA_TYPE        = CHARACTER
   START_BYTE       = 244
   DESCRIPTION      = "UTC time in YYDOYTHH:MM:SS.00 format derived from the 
   MID_SPECTRUM_TIME using SPICE kernels. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = WAVELENGTH
   COLUMN_NUMBER    = 22
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 261
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Wavelength vector of the spectral scan, which can be 
   up to 25 elements. Shorter scans are padded with zeros. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = RADIANCE_KR
   COLUMN_NUMBER    = 23
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 461
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Vector of calibrated radiances matched with scan 
   WAVELENGTH; up to 25 elements. Shorter scans are padded with zeros. 
   Unit = kiloRayleighs/nanometer. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = RADIANCE_SNR
   COLUMN_NUMBER    = 24
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 661
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Vector of calibrated radiance SNR matched with scan 
   WAVELENGTH; up to 25 elements. Shorter scans are padded with zeros.
   Derived signal-to-noise in fully calibrated radiance, propagated from
   fully corrected count rate uncertainty and sensitivity uncertainty. 
   Unitless fraction, applied to radiance. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TOTAL_RADIANCE_KR
   COLUMN_NUMBER    = 25
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 861
   DESCRIPTION      = "Total radiance integrated over the specified emission 
   line(s) in the given calibrated spectrum. Unit = kiloRayleighs. PER 
   SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TOTAL_RADIANCE_SNR
   COLUMN_NUMBER    = 26
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 869
   DESCRIPTION      = "Derived SNR in the total radiance, propagated from
   radiance SNR. Unitless fraction, applied to total radiance. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SLIT_POS
   COLUMN_NUMBER    = 27
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 877
   DESCRIPTION      = "Indicates whether slit mask is in atmospheric or 
   surface position. Atmospheric slit results in a 1 deg. by 0.04 deg. 
   instantaneous field of view (iFOV). Surface slit results in a 0.05 deg. 
   by 0.04 deg. iFOV. Surface=0, Atmosphere=1.  Unitless, PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_1
   COLUMN_NUMBER    = 28
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 879
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_2
   COLUMN_NUMBER    = 29
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 887
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_3
   COLUMN_NUMBER    = 30
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 895
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_4
   COLUMN_NUMBER    = 31
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 903
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN
 
 
APPENDIX G- UVVSSUMD.FMT FILE

NOTE = "All 'PER SPECTRAL SCAN' geometry and time columns are defined at the
midpoint (middle wavelength) of the observed spectral scan."

OBJECT        = COLUMN
   NAME             = OBSERVATION_TYPE
   COLUMN_NUMBER    = 1
   BYTES            = 30
   DATA_TYPE        = CHARACTER
   START_BYTE       = 1
   DESCRIPTION      = "Name of the observation type. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = CDR_NAME
   COLUMN_NUMBER    = 2
   BYTES            = 27
   DATA_TYPE        = CHARACTER
   START_BYTE       = 31
   DESCRIPTION      = "Name of the CDR from which the data were extracted.
   PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

/* SPICE DERIVED GEOMETRY VALUES */

OBJECT        = COLUMN
   NAME             = PLANET_SUN_VECTOR_TG
   COLUMN_NUMBER    = 3
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 58
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving center-to-center 
   planet-sun position in target body-fixed coordinate system at midpoint of 
   scan. Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_SC_VECTOR_TG 
   COLUMN_NUMBER    = 4
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 82
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving center-to-center 
   planet-spacecraft position in target body-fixed coordinate system at 
   midpoint of scan. Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = BORESIGHT_UNIT_VECTOR_CENTER_TG
   COLUMN_NUMBER    = 5
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 106
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived (x,y,z) vector giving look direction of MASCS 
   UVVS center in target body-fixed coordinate system at midpoint of 
   spectral scan. Unit = N/A. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LATITUDE
   COLUMN_NUMBER    = 6
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 130
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Latitude below the tangent point of the UVVS 
   field-of-view center. Measured at midpoint of spectral scan. 
   Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LONGITUDE  
   COLUMN_NUMBER    = 7
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 138
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Longitude below the tangent point of the UVVS
   field-of-view center. Measured at midpoint of spectral scan. 
   Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_ALTITUDE
   COLUMN_NUMBER    = 8
   BYTES            = 24
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 146
   ITEMS            = 3
   ITEM_BYTES       = 8
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Altitude (center, min, max) of the actual field-of-
   view slit projection. Measured at midpoint of spectral scan. 
   Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TARGET_LOCAL_TIME
   COLUMN_NUMBER    = 9
   BYTES            = 4
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 170
   DESCRIPTION      = "Local time of the tangent point of the UVVS
   field-of-view center. Local time is defined as 0 at midnight, 6 at dawn,
   and 12 at noon. Measured at midpoint of spectral scan. Unit= hour plus 
   fraction of hour. (e.g. 1.5 = 90 minutes). PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LATITUDE
   COLUMN_NUMBER    = 10
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 174
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subspacecraft latitude on planet surface. 
   Measured at the midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSPACECRAFT_LONGITUDE
   COLUMN_NUMBER    = 11
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 182
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subspacecraft longitude on planet surface. 
   Measured at the midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPACECRAFT_ALTITUDE
   COLUMN_NUMBER    = 12
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 190
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived spacecraft altitude above nadir point.
   Unit = kilometers. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPACECRAFT_LOCAL_TIME
   COLUMN_NUMBER    = 13
   BYTES            = 4
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 198
   DESCRIPTION      = "Local time of the subspacecraft point. Local time is 
   defined as 0 at midnight, 6 at dawn, and 12 at noon. Measured at midpoint 
   of spectral scan. Unit= hour plus fraction of hour. 
   (e.g. 1.5 = 90 minutes). PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LATITUDE
   COLUMN_NUMBER    = 14
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 202
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subsolar latitude on planet surface.
   Measured at midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SUBSOLAR_LONGITUDE
   COLUMN_NUMBER    = 15
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 210
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived subsolar longitude on planet surface. 
   Measured at midpoint of spectral scan. Unit = degrees. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = PLANET_TRUE_ANOMALY
   COLUMN_NUMBER    = 16
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 218
   MISSING_CONSTANT = -1.E32
   DESCRIPTION      = "Derived true anomaly of planet. Measured at midpoint 
   of spectral scan. Unit = degrees. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = ORBIT_NUMBER
   COLUMN_NUMBER    = 17
   BYTES            = 4
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 226
   DESCRIPTION      = "Mercury orbit number. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = MET_PARTITION
   COLUMN_NUMBER    = 18
   BYTES            = 4
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 230
   DESCRIPTION      = "Spacecraft clock partition number used in conjunction
     with MET value to perform time conversion using SPICE kernels. 
     Introduced due to the MET rollover on 2013-01-08 which reset the MET
     value to 1000."
END_OBJECT    = COLUMN

/* CALIBRATED ITEMS AND ADDITIONAL METADATA */

OBJECT        = COLUMN
   NAME             = MID_SPECTRUM_TIME
   COLUMN_NUMBER    = 19
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 234
   DESCRIPTION      = "A calculated value indicating the mission elapsed
   time since launch at the middle of an individual UVVS spectral scan. 
   Unit = seconds. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = UTC_TIME
   COLUMN_NUMBER    = 20
   BYTES            = 17
   DATA_TYPE        = CHARACTER
   START_BYTE       = 242
   DESCRIPTION      = "UTC time in YYDOYTHH:MM:SS.00 format derived from the 
   MID_SPECTRUM_TIME using SPICE kernels. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = WAVELENGTH
   COLUMN_NUMBER    = 21
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 259
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Wavelength vector of the spectral scan, which can be 
   up to 25 elements. Shorter scans are padded with zeros. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = RADIANCE_KR
   COLUMN_NUMBER    = 22
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 459
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Vector of calibrated radiances matched with scan 
   WAVELENGTH; up to 25 elements. Shorter scans are padded with zeros. 
   Unit = kiloRayleighs/nanometer. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = RADIANCE_SNR
   COLUMN_NUMBER    = 23
   BYTES            = 200
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 659
   ITEMS            = 25
   ITEM_BYTES       = 8
   DESCRIPTION      = "Vector of calibrated radiance SNR matched with scan 
   WAVELENGTH; up to 25 elements. Shorter scans are padded with zeros.
   Derived signal-to-noise in fully calibrated radiance, propagated from
   fully corrected count rate uncertainty and sensitivity uncertainty. 
   Unitless fraction, applied to radiance. PER SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TOTAL_RADIANCE_KR
   COLUMN_NUMBER    = 24
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 859
   DESCRIPTION      = "Total radiance integrated over the specified emission 
   line(s) in the given calibrated spectrum. Unit = kiloRayleighs. PER 
   SPECTRAL SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = TOTAL_RADIANCE_SNR
   COLUMN_NUMBER    = 25
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 867
   DESCRIPTION      = "Derived SNR in the total radiance, propagated from
   radiance SNR. Unitless fraction, applied to total radiance. PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SLIT_POS
   COLUMN_NUMBER    = 26
   BYTES            = 2
   DATA_TYPE        = MSB_UNSIGNED_INTEGER
   START_BYTE       = 875
   DESCRIPTION      = "Indicates whether slit mask is in atmospheric or 
   surface position. Atmospheric slit results in a 1 deg. by 0.04 deg. 
   instantaneous field of view (iFOV). Surface slit results in a 0.05 deg. 
   by 0.04 deg. iFOV. Surface=0, Atmosphere=1.  Unitless, PER SPECTRAL 
   SCAN."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_1
   COLUMN_NUMBER    = 27
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 877
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_2
   COLUMN_NUMBER    = 28
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 885
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_3
   COLUMN_NUMBER    = 29
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 893
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN

OBJECT        = COLUMN
   NAME             = SPARE_4
   COLUMN_NUMBER    = 30
   BYTES            = 8
   DATA_TYPE        = IEEE_REAL
   START_BYTE       = 901
   DESCRIPTION      = "SPARE column."
END_OBJECT    = COLUMN


APPENDIX H- SPICE Kernel Files Used In Messenger Data Products

The following SPICE kernel files are used to compute the UTC time and any 
geometric quantities found in the PDS labels.  Kernel files are generated 
throughout the mission with a file naming convention specified by the 
MESSENGER project.  The files are archived at and accessible from the PDS 
NAIF Node.

*.bsp:   
MESSENGER spacecraft ephemeris file. Also known as the Planetary Spacecraft 
Ephemeris Kernel (SPK) file.

*.bc:    
Messenger spacecraft orientation file. Also known as the Attitude C-Kernel 
(CK) file.

*.tsc:   
Messenger spacecraft clock coefficients file. Also known as the Spacecraft 
Clock Kernel (SCLK) file.

*.tpc:  
Planetary constants file. Also known as the Planetary Constants Kernel (PcK) 
file.

*.tls:
Leapseconds kernel file. Used in conjunction with the SCLK kernel to convert 
between Universal Time Coordinated (UTC) and MESSENGER MET (Mission Elapsed 
Time). Also called the Leap Seconds Kernel (LSK) file.


APPENDIX I- CODMAC/NASA Definition of Processing Levels for Science Data Sets

CODMAC Level
Proc. Type
Data Processing Level Description

1
Raw Data
Telemetry data with data embedded.

2
Edited Data
Corrected for telemetry errors and split or decommutated into a data set for 
a given instrument.  Sometimes called Experiment Data Record (EDR). Data are 
also tagged with time and location of acquisition. 
Corresponds to NASA Level 0 data.

3
Calibrated Data
Edited data that are still in units produced by instrument, but have been 
corrected so that values are expressed in or are proportional to some 
physical unit such as radiance.  No resampling, so edited data can be 
reconstructed. 
Corresponds to NASA Level 1A.

4
Resampled data
Data that have been resampled in the time or space domains in a such way 
that the original edited data cannot be reconstructed.  Could be calibrated 
in addition to being resampled. 
Corresponds to NASA Level 1B.

5
Derived Data
Derived results, as maps, reports, graphics, etc. 
Corresponds to NASA Levels 2 through 5

6
Ancillary Data
Non-Science data needed to generate calibrated or resampled data sets. 
Consists of instrument gains, offsets; pointing information for scan 
platforms, etc.

7
Corrective Data
Other science data needed to interpret space-borne data sets. May include 
ground based data observations such as soil type or ocean buoy measurements 
of wind drift.

8
User Description
Description of why the data were required, any peculiarities associated with 
the data sets., and enough documentation to allow secondary user to extract 
information from the data.

n
n
Not Applicable

The above is based on the national research council committee on data 
management and computation (CODMAC) data levels.



APPENDIX J- ACRONYMS

ACT          Applied Coherent Technology Corporation
APL          The John Hopkins University Applied Physics Laboratory
ASCII        American Standard Code for Information Interchange
CCSDS        Consultative Committee for Space Data Systems
CDR          Calibrated Data Record
CK           MESSENGER spacecraft orientation file (SPICE)
CoDMAC       Committee on Data Management and Computation
Co-I         Co-Investigator
DDR          Derived Data Record
DEB          Digital Electronics Board
DN           Data Number, the raw telemetry count
DPU          Data Processing Unit
DSN          Deep Space Network
EDR          Experiment Data Records
EPPS         Energetic Particle and Plasma Spectrometer
ET           Ephemeris Time
FIPS         Fast Imaging Plasma Spectrometer
FOV          Field of View
FUV          Far Ultraviolet PMT channel of the UVVS 
FPGA         Field Programmable Gate Array
FTP          File Transfer protocol
GC           Geochemistry Group
GDLCI        Grating Drive Loop Control Interrupt. Refers to timing unit in 
             MASCS UVVS
GP           Geophysics Group
GRNS         Gamma-ray and Neutron Spectrometer
GRS          Gamma-ray Spectrometer
GSFC         Goddard Space Flight Center
HK           Housekeeping data
HVPS         High Voltage Power Supply
I&T          Integration and Test 
I2C          Inter-Integrated Circuit
IEEE         Institute of Electrical and Electronics Engineers
IEM          Integrated Electronic Module
IR           Infrared channel of the MASCS instrument
J2000        The celestial reference frame defined using Julian epoch 2000
LVPS         Low Voltage Power Supply
LSK          Leapseconds Kernel (SPICE)
MAG          Magnetometer
MASCS        Mercury Atmospheric and Surface Composition Spectrometer
MDIS         Mercury Dual Imaging System
MESSENGER    MEssenger, Surface, Space ENvironment, GEochemistry, and Ranging
MET          Mission Elapsed Time
MLA          Mercury Laser Altimeter
MOC          Mission Operations Center
MSB          Most Significant Bit
MUV          Mid Ultraviolet PMT channel of the UVVS
NAIF         Navigation and Ancillary Information Facility
NIR          Near Infra-red detector for the VIRS instrument
NS           Neutron Spectrometer
PAA          Phased-Array Antenna
PCK          Planetary Constant Kernel (SPICE)
PDS          Planetary Data System
PMT          Photomultiplier Tube. Refers to the UVVS detectors.
RDR          Reduced Data Record
SBOS         Software Bright Object Sensor. Refers to detector saving 
             mechanism on MASCS UVVS
SCLK         Spacecraft Clock Kernel (SPICE)
SIS          Software Interface Specification
SOC          Science Operations Center
SPICE        Spacecraft, Planet, Instrument, C-matrix Events, refers to the 
            kernel files and functions used to generate viewing geometry
SPK          Spacecraft and Planets Kernel (SPICE)
UTC          Coordinated Universal Time
UVVS         Ultraviolet and Visible Spectrometer
VIS          Visible channel (applies to both VIS PMT and VIS Array detector 
             in MASCS)
VIRS         Visible and Infrared Spectrograph
XRS          X-Ray Spectrometer 


APPENDIX K- MASCS Instrument Overview 

Ultraviolet and Visible Spectrometer

Focal length        125 mm
Grating             2400 g/mm blazed at 330 nm
Spectra resolution  0.5 nm FUV channel
                    0.7 nm MUV channel
                    0.6 nm VIS channel
Wavelength range:
  FUV channel       115-190 nm (2nd order)
  MUV channel       160-320 nm (1st order)
  VIS channel       250-600 nm (1st order)
Detector:
  FUV channel       Hamamatsu R1081 PMT - CsI
  MUV channel       Hamamatsu R759 PMT - CsTe
  VIS channel       Hamamatsu R760P PMT - BiAlkali
Field of view:
  FUV, MUV, VIS     1.0 x 0.04 deg. Atmosphere
  FUV, MUV, VIS     0.05 x 0.04 deg. Surface

Visible and Infrared Spectrograph
      
Focal length        210 mm
Grating             100 g/mm sinusoidal profile
Spectral resolution 4.7 nm
Wavelength range:
  VIS channel       300-1050 nm
  IR channel        850-1450 nm 
Detector:
  VIS channel       Hamamatsu S3901-512SPL Si Diode Array
  IR channel        Hamamatsu G8162-256S InGaAs Diode Array
Field of view:      0.023 deg. diameter


APPENDIX L- MASCS Data Product Summary

See PDF version of document for table.