PDS_VERSION_ID         = PDS3 

RECORD_TYPE            = STREAM
INSTRUMENT_HOST_NAME   = "2001 MARS ODYSSEY"
INSTRUMENT_NAME        = "GAMMA RAY SPECTROMETER"
TARGET_NAME            = MARS
OBJECT                 = TEXT
  PUBLICATION_DATE     = 2003-10-30
  NOTE                 = "Introduction to Odyssey GRS DHD" 
END_OBJECT             = TEXT
END 
                                                
    2001 MARS ODYSSEY GAMMA RAY SPECTROMETER DERIVED HEND DATA

Introduction
------------

The Odyssey Gamma Ray Spectrometer (GRS) Derived HEND Data (DHD)
products are background subtracted count values needed to calculate
neutron counting rates. They are derived from HEND EDRs.

Information about the DHD product can be found in the GRS Intermediate
Data Record Software Interface Specification (SIS) in the DOCUMENT
directory of this archive. Information about the processing applied to
these products can be found in the HEND Processing document in the
same directory.

File Formats
------------

The GRS DHD product is structured as a time series in a 22-column
binary table. A detached PDS label describes the format and contents
of each of the columns in the table. One file contains one day's worth
of data.

File names for GRS DHD data files have the form of DHD_yyyymmdd.DAT,
where yyyymmdd indicates the year, month and day on which the data
were acquired. An example file name is DHD_20030419.DAT.

Each data file is described by an ASCII text PDS label in a separate
file with the same name, extension ".LBL", in the same directory as
the data file.  The labels contain identification and observation
parameters associated with the data files and definitions for the
TABLE object.  The PDS labels include a pointer to a format file that
contains column definitions (extension ".FMT"). The format file is
found in the LABEL directory.

Volume Contents
---------------

The GRS AHD archive volume includes the following files and
directories.

Root directory
  AAREADME.TXT - the file you are reading
  ERRATA.TXT   - notes and errata, if any
  VOLDESC.CAT  - volume description for the PDS catalog

INDEX directory
  INDXINFO.TXT - description of contents of this directory
  INDEX.TAB    - index of all products in the archive
  INDEX.LBL    - PDS label that describes INDEX.TAB

DOCUMENT directory
  DOCINFO.TXT  - description of contents of this directory
  GRS-IDR-SIS.PDF - detailed data product description in PDF format
  GRS-IDR-SIS.LBL - PDS label for GRS-IDR-SIS.PDF
  GRS_HEND_PROCESSING.PDF - description of processing applied to 
      AHD products
  GRS_HEND_PROCESSING.LBL - PDS label for GRS_HEND_PROCESSING.PDF
  TIME_CONVERSION_TABLES.PDF - tables for converting Earth to Mars time
  TIME_CONVERSION_TABLES.LBL - PDS label for TIME_CONVERSION_TABLES.PDF

CATALOG directory
  CATINFO.TXT  - description of contents of this directory
  *.CAT        - descriptions of dataset, instrument, spacecraft,
                 mission, and personnel for the PDS catalog

LABEL directory
  LABINFO.TXT  - description of contents of this directory
  DERIV_HEND_DATA_COLS.FMT - format of columns in DHD data file

SOFTWARE directory
  GRS_CODE.ZIP - library of Java source code to parse DHD data files
  GRS_CODE.LBL - PDS label for GRS_CODE.ZIP
  GRS_CODE_DOC.ZIP - documentation for Java code
  GRS_CODE_DOC.LBL - PDS label for GRS_CODE_DOC.ZIP 
  SOFTINFO.TXT - description of contents of this directory

Data directories 

  Top-level data directories are named for the year, e.g. 2002.
  Beneath these directories are subdirectories named for
  a single day, e.g. 20020219. Each subdirectory
  contains a data file and detached PDS label.


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