PDS_VERSION_ID          = PDS3
LABEL_REVISION_NOTE     = "2018-10-16 GEO:SHS Added pointer to README.TXT
                           for the PDS4 archive"
RECORD_TYPE             = STREAM
OBJECT                  = TEXT
  PUBLICATION_DATE      = 2013-10-07
  NOTE                  = "AAREADME.TXT describes this volume."
END_OBJECT              = TEXT
END

PLEASE NOTE: This archive has been migrated from PDS3 to PDS4. The
contents and directory structure of the PDS3 archive have not changed, 
but PDS4 metadata in the form of XML files have been added. 
The file README.TXT in the root directory has more information.
The file you are now reading, AAREADME.TXT, was written for the original
PDS3 archive and does not have information about the PDS4 additions.

---- Original contents of AAREADME.TXT are below this line. ----

MESSENGER Gamma Ray Spectrometer CDR/RDR/DAP Data Archive

Prepared for the Geosciences Discipline Node of the Planetary Data System 

========================================================================
Introduction
========================================================================

This volume contains calibrated (CDR), reduced (RDR), and derived (DAP) data 
and associated documentation from the MESSENGER Gamma Ray Spectrometer 
(GRS).

A complete description of the design of this volume is given in the GRS
CDR/RDR/DAP Software Interface Specification (SIS). An electronic copy of 
this document is located in the /DOCUMENT directory.

This volume is intended for the use of scientists and students in the study 
of the geography and geochemistry of the planet Mercury. The data may be 
used for research and publication.

========================================================================
Volume Format
========================================================================

All science data are located under the DATA directory. The INDEX directory 
contains a listing of all of the data products included on this volume.

The CATALOG directory contains PDS documentation describing the mission,
spacecraft, instrument, and data set. These include:

  CATINFO.TXT                   Description of the CATALOG directory 
                                contents
  CDR_RDR_DS.CAT                GRS CDR and RDR data set descriptions
  DAP_DS.CAT                    GRS DAP data set description
  DSMAP.CAT                     DAP data set projection description
  INSTRUMENT_HOST.CAT           MESSENGER spacecraft description
  INSTRUMENT.CAT                GRS instrument description
  MISSION.CAT                   MESSENGER mission description
  PERSON.CAT                    GRNS personnel contact information.
  REF.CAT                       MESSENGER mission reference information,
                                including GRS references.

Additional information on volume organization is given in the CDR/RDR/DAP 
SIS (described above), and in the section "Volume Contents" below.

========================================================================
File Formats
========================================================================

The CDR and RDR data files on this volume are provided in flat IEEE binary 
format (extension .DAT). The DAP data files on this volume are stored as 
jpeg2000 image files (extension .JP2). Each data file is accompanied by a 
detached PDS label file (extension .LBL), an ASCII file containing 
information describing the data file and data record format.

Text files and detached label files contain ASCII records terminated with a 
carriage-return character (ASCII 13) and a line-feed character (ASCII 10).
This format allows the files to be read by MacOS, DOS, UNIX and VMS 
operating systems. Note that while both label and catalog files are ASCII, 
some operating systems will not recognize the .LBL and .CAT extensions as 
ASCII types. It may be necessary to either remap these extensions as ASCII 
in the system or text browser, or else to open the files from within the 
text browser.

========================================================================
Volume Contents
========================================================================

Directory Structure and Contents for GRS CDR/RDR/DAP Data Archive Volume

The following illustration shows the directory structure overview for the 
GRS CDR/RDR/DAP archive volume, which bears the PDS-assigned volume ID 
MESSGRS_2001. This volume contains the GRS CDR, RDR, and DAP data products, 
supporting documentation, and any additional files required for the volume 
to be compliant with PDS standards. The content of the volume is expected to 
be updated with periodic releases according to the schedule found in the 
MESSENGER Data Management and Archiving Plan. Revised CDRs/RDRs/DAPs (if 
needed) will also be delivered according to the same schedule. Revised 
CDRs/RDRs/DAPs will have an incremented version number in the PDS label.

Directory Structure Overview

                             <ROOT>
 ______________________________|___________________________________
   |         |         |       |        |         |          |
 <DATA>  <GEOMETRY> <INDEX> <LABEL> <CATALOG> <DOCUMENT> <SOFTWARE>
 __|_______________________________________________________________
   |          |          |                                   |
 <YYYY>     <YYYY>     <YYYY>                              <MAPS>
  _|______________________________________________
      |       |                                |
     <01>     <02>                            <12>
  ____|___________________________________
  |            |                       |
 <01>         <02>                    <31>
  |            |                       |
 <GRS_ENG>    <GRS_ENG>            <GRS_ENG>
 

Directory Contents:

<ROOT> Directory

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

AAREADME.TXT: (This file) General information file. Provides users with
information about the MESSENGER GRS data products. Directs users to other
documents on the volume containing more detailed information.

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 will be documented in this file. This 
includes revised CDR/RDRs/DAPs meant to replace CDR/RDRs/DAPs in a previous 
PDS delivery.

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.


<DATA> Data Directory

This is the top level of the directories containing CDR/RDRs/DAPs.

<DATA/MAPS> Data Directory

Sub-directory of the <DATA> directory containing the DAPs.

<DATA/YYYY> Data Directory

Sub-directory of the <DATA> directory for each year.

<DATA/YYYY/MM> Data Directory

Sub-directory of the <DATA/YYYY> directory for each month of the year where
MM ranges from 01 through 12. Data acquired after March 17, 2013 
(GRS_CAL_SH3, GRS_CAL_SCR) are included in the MM directories.  Data 
acquired prior to this date reside in the DD directories (see below).

<DATA/YYYY/MM/DD> Data Directory

Sub-directories of a <DATA/YYYY/MM> directory, these are the top directories
for the CDR/RDR data products. The names of the data directories identify the
day of the month for the start time of the data products contained in the 
directories. Please note that the day folders (DD) are excluded for data 
acquired after March 17, 2013.

<DATA/YYYY/MM/DD/GRS_ENG> Data Directory

Sub-directory of a <DATA/YYYY/MM/DD> directory, this directory contains
CDR/RDR engineering data products.


<GEOMETRY> Directory

The top level directory for geometry files.

GEOMINFO.TXT: Description of geometry directory files and instructions on 
how to retrieve SPICE files from NAIF.


<INDEX> Directory

This subdirectory contains the indices for the GRS CDR/RDR/DAP data 
products. The following files are contained in the index subdirectory.

INDEX.LBL: Detached PDS label for INDEX.TAB.

INDEX.TAB: The CDR/RDR/DAP index file is organized as a table; there is one 
entry for each of the data files included in the GRS data set; the columns 
contain parameters that describe the data as well as instrument and 
spacecraft parameters.

INDXINFO.TXT: Identifies and describes the function of each file in the 
index subdirectory. This includes a description of the structure and 
contents of each index table in the subdirectory AND usage notes.

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.


<LABEL> Label Directory

This subdirectory contains the format files for each of the different 
CDR/RDR product types. The format file describes the format of the binary 
table object in the CDR/RDR data file.

LABINFO.TXT: Identifies and describes the function of each file in the
label subdirectory.

GRS_CAL_AC.FMT: The format of the Calibrated HPGE Anti-Coincident Spectra
data table.

GRS_CAL_RAW.FMT: The format of the Calibrated HPGE Raw Spectra data table.

GRS_CAL_SH.FMT: The format of the Calibrated Shield Spectra data table for 
data taken before the FSW update on September 17, 2010.

GRS_CAL_SH2.FMT: The format of the Calibrated Shield Spectra data table for 
data taken after the FSW update on September 17, 2010.

GRS_CAL_SH3.FMT: The format of the Calibrated Shield Spectra data table for 
data taken after the FSW update on March 17, 2013.

GRS_CAL_SCR.FMT: The format of the Calibrated Shield Count Rate data table.

GRS_ENG.FMT: The format of the Calibrated Engineering data table.

GRS_RDR_SUMS.FMT: The format of the Reduced Gamma Sums data table.


<CATALOG> Directory

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

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

CDR_RDR_DS.CAT: Describes the general content of the CDR and RDR dataset and 
includes information about the duration of the mission and the person or 
group responsible for producing the data.

DAP_DS.CAT: Describes the general content of the DAP dataset and includes 
information about the duration of the mission and the person or group 
responsible for producing the data.

DSMAP.CAT: Describes the DAP dataset simple cylindrical map projection.

INSTRUMENT_HOST.CAT: Describes the MESSENGER spacecraft.

INSTRUMENT.CAT: Describes physical attributes of the GRS instrument and
provides relevant references to published literature.

MISSION.CAT: Describes the scientific goals and objectives of the MESSENGER 
program. It also identifies key people and institutions.

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

REF.CAT: Provides references (reference objects) to scientific papers and 
other publications of interest to those using the data, both for GRS and the 
mission as a whole.


<DOCUMENT> Directory

This subdirectory contains the documentation that is needed to understand 
and analyze the CDR/RDR/DAP data products. Documents are stored in PDF and 
HTML format.

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

GRS_CDR-RDR-DAP_SIS.LBL: Detached PDS label for GRS_CDR-RDR-DAP_SIS.PDF and
GRS_CDR-RDR-DAP_SIS.HTM.

GRS_CDR-RDR-DAP_SIS.PDF: The GRS CDR-RDR-DAP SIS: "MESSENGER Gamma Ray 
Spectrometer Calibrated Data Record, Reduced Data Record, and Derived 
Analysis Product Software Interface Specification" in Adobe Acrobat format.

GRS_CDR-RDR-DAP_SIS.HTM: The GRS CDR-RDR-DAP SIS: "MESSENGER Gamma Ray 
Spectrometer Calibrated Data Record, Reduced Data Record, and Derived 
Analysis Product Software Interface Specification" in HTML format. 
Associated image files are in the "GRS_CDR-RDR-DAP_SIS_FILES" folder.

MESSGRS_PROCESSING.LBL: Detached PDS label for MESSGRS_PROCESSING.PDF and
MESSGRS_PROCESSING.HTM.

MESSGRS_PROCESSING.PDF: "MESSENGER Gamma Ray Spectrometer (GRS) 
EDR-to-CDR-to-RDR-to-DAP Processing" document in Adobe Acrobat format.

MESSGRS_PROCESSING.HTM: "MESSENGER Gamma Ray Spectrometer (GRS) 
EDR-to-CDR-to-RDR-to-DAP Processing" document in HTML format. Associated 
image files are in the "MESSGRS_PROCESSING_FILES" folder.

PDS_GRS_SUMMARY.TXT: Provides a summary of non-mapped GRS results.

JP2INFO.TXT: JP2 description file referenced by DAP labels.


<SOFTWARE> Directory

This subdirectory contains information about software for reading the data
products.

SOFTINFO.TXT: Description of MESSENGER GRS PDS Viewer software.

========================================================================
Related PDS Products
========================================================================

The GRS CDR data set is derived from the GRS EDR data set 
(PDS Data Set ID MESS-E/V/H-GRNS-2-GRS-RAWDATA-V1.0, volume ID MESSGRS_1001).
The GRS CDR data set is intended to be used to derive the GRS RDR data set, 
and the RDR is intended to be used to derive the DAP maps. The GRS EDR, CDR, 
RDR, and DAP data sets are available from the Planetary Data System 
(http://pds.nasa.gov).

========================================================================
Errata
========================================================================

Every effort has been made to ensure that the data and documentation are of 
the best possible quality. However, all users are encouraged to verify the 
correctness of the data prior to submitting any publications or other work 
based on these data.

The file ERRATA.TXT at the root level of this volume contains a list of 
known deficiencies or caveats associated with data on this volume at the 
time it was published, if any. It also lists any revisions that have been 
made to the data set as a whole or to individual products.

If you find an error on this volume, please report the error to the PDS
Geosciences Node at geosci@wunder.wustl.edu.


========================================================================
Contacts
========================================================================

For questions concerning these data products and documentation, contact:

          PDS Geosciences Node
          Washington University
          Dept. of Earth and Planetary Sciences
          1 Brookings Drive
          St. Louis, MO 63130
          314-935-5493

          WWW Site:  http://pds-geosciences.wustl.edu
          Electronic mail address:  geosci@wunder.wustl.edu


For questions regarding PDS Standards or other archive volumes available
from the PDS, please contact PDS Operator at the PDS Central Node (at JPL):


    Internet            pds_operator@jpl.nasa.gov
    Telephone           (818) 354-4321
    U.S. Mail           Planetary Data System, PDS Operator
                        Jet Propulsion Laboratory
                        Mail Stop 202-101
                        4800 Oak Grove Dr.
                        Pasadena, CA 91109-8099