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PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
OBJECT = TEXT
INTERCHANGE_FORMAT = ASCII
PUBLICATION_DATE = 2002-07-01
NOTE = "AAREADME.TXT File for data set:
NEAR-A-GRS-3-EDR-EROS/ORBIT-V1.0"
END_OBJECT = TEXT
END
NEAR Mission GAMMA-RAY SPECTROMETER Level-2 Data Set
========================================================================
1. Introduction
____________
This document provides an overview of the Near Earth Asteroid
Rendezvous Gamma-Ray Level 2 data archives. This volume contains
science data products from observations acquired by the Near Earth
Asteroid Rendezvous (NEAR) Gamma-ray Spectrometer (GRS) instrument.
The GRS Level 2 data products in this archive include daily time
series of spectra collected by the instrument along with selected
spacecraft engineering and instrument configuration and orbital
ephemerides. Supporting documentation is included for the specifics
of how these data were generated.
2. Documentation
_____________
This document provides an overview of the Near Earth Asteroid
Rendezvous Gamma-Ray Level 2 document archive. These documents describe
the design, development, implementation, calibration and operations
of the NEAR GRS instrument. The directory contains references for
2 documents that could not be included in this archive due to
copyright concerns and are cited in the REFERENCES.CAT file.
Additional documentation is found in the DOCUMENTATION directory,
including a document describing the GRS instrument calibrations.
3. Observation Log
_______________
This document provides an overview of the Near Earth Asteroid
Rendezvous Gamma-Ray Level 2 Observation Log archive. These documents
describe the systems that were used to command and control the
spacecraft during times when XGRS was controlling attitude, as well
as commands that were used to configure the instrumentation during
the orbital encounter.
4. Volume Set Information
______________________
Calibrated Level 2 Products
The Level 2 data product comprises the time series of the GRS
instrument'sscience data in physical units. At each integration
time the instrument Data Processing Unit (DPU) samples instrument
spectra accumulated during the integration period as well as
instrument and engineering configurationinformation. Ground
processing activities at the University of Arizona produce
Derived Engineering and Spatial Ephemerides information. The
Level-2 data are then combined into integral products within
a relational database and exported as an integral Level-2
product. Each GRS record is comprised of the following logical
data units:
Spectra:
5, (1024 Channel) Spectra
(NAI, BGO, ANTI, NAI1, NAI2, BGO1, BGO2)
NAI = Sodium Iodide: Asteroid Pointing
BGO = Bismuth Germanate: Asteroid Pointing
ANTI= Anti-Coincidence: Asteroid Pointing
NAI1= Sod. Iod 1 Escape: Asteroid Pointing
NAI2= Sod. Iod 2 Escape: Asteroid Pointing
2, (21 Channel) Spectra
BGO1= Bis. Germ. 1 Escpe:Asteroid Pointing
BGO2= Bis. Germ. 2 Escpe:Asteroid Pointing
Instrument HouseKeeping:
Instrument Rates and activity
Engineering Housekeeping:
Engineering Configurations
Derived Engineering:
Ground derived data products
Spatial
Orbital Ephemerides
4. CD-ROM Format
_____________
The CD-ROM has been formatted so that a variety of computer systems
(e.g.,PC, Macintosh, and Sun) may access the data. Specifically, it
is formatted according to the ISO-9660 level 1 Interchange Standard.
For further information, refer to the ISO-9660 Standard Document:
RF# ISO 9660- 1988, April 15, 1988.
This CD-ROM does not contain any Extended Attribute Records (XAR).
Thus, VAX/VMS users may have some problems accessing files on this
volume.
5. File Formats
____________
The GRS Level 2 integral data are BINARY files the describe the
integrated composition of spectral, orbital ephemerides, instrument
configuration and derived products for each GRS integration period.
Descriptions of each integral file comes with a detached PDS header
label. A header label file describes attributes specific to each
integration. Each header references a common label file for each
integral file. An observation log file is included also an ASCII
table described by its corresponding detached label.
All text files (*.TXT files) and detached labels (*.LBL files) on
this volume,are stream format files, with a carriage return
(ASCII 13) and a line feed character (ASCII 10) at the end of each
line. This allows the files to be read by the MacOS, DOS, and UNIX
operating systems.
An example format of each Level-2 BINARY record file is:
Example: g2000011.dat
where g = Gamma-ray Spectrometer
2000 = Year
011 = Day Number
.dat = file extension
For the complete description of the GRS Level-2 Products see:
"The Near Earth Asteroid Rendezvous, Gamma-ray Spectrometer, Level-2
Requirements Specification": May 25, 2001
in the DOCUMENT section.
For the PDS submission Level-2 Integral products have been exported
on a daily basis. Each day's GRS data collection will be stored
in a daily directory comprised of variable number`s of integral
records. The directory format is listed below in the directory
elaboration.
6. Volume Contents
_______________
Files on this volume are organized into a series of subdirectories
below the top-level directory. The following table shows the
structure and content of these directories. In the table,
directory names are enclosed in square brackets ([]).
FILE CONTENTS
Top-level directory
|
|- AAREADME.TXT The file you are reading.
|
|- [DATA]
| |- DATAINFO.TXT Description of files in the DATA directory.
| |
| |- [200001] Jan 2000 Month Reference Dir
| | |- G2000011.* Daily Spectra Set,G=GRS,200X=yr,NNN=daynumber
| | |- ..... All days in Jan. 2000
| |
| |- [200002] Feb 2000 Month Reference Dir
| | |- G2000032.* Daily Spectra Set,G=GRS,200X=yr,NNN=daynumber
| | .......... All months 2000 to Feb 2001
| |- [200102] Feb 2000 Month Reference Dir
| | |- G2001043 Daily Spectra Set,G=GRS,200X=yr,NNN=daynumber
| | |- ....... Up to Feb 11, 2001 Coverage Stops
| |
|
|- [DOCUMENT] GRS Documentation file.
| |- DOCINFO.TXT Description of files DOCUMENT directory.
|- |- GRS_REQS_7_2.DOC NEAR-GRS L-2 Requirement Specs (MS Word)
|- |- GRS_REQS_7_2.LBL Label file for GRS L-2 Reqs Doc versions
|- |- GRS_REQS_7_2.TXT Reduced form, NEAR GRS Reqs specs. (ASCII)
|- |- GRS_REQS_7_2.JPG Reqs. saved as multi-page Jpeg file.
|- |- GRS_REQS_7_2.TIF Reqs. saved as multi-page TIF file.
|- |- GRS_REQS_7_2_*
| |- Individual Pages NEAR GRS L-2 Reqs Spec.
| |- Saved as 1 page per TIF file, * = Page #
| |- Also included label file each TIF image
| |
| |- [OBSERVATION_LOG]
| | |- OBSLOGINFO.TXT Description of OBS LOG Dir
| | |- XGRS_COMMAND_DESC* Obs log, config parms
| | |- XGRS_INST_USER_GUIDE4* Command, CAS generation instr.
| | |- XGRS_OBSLOG* Actual XGRS command log
| |
|
| |- [INSTRUMENT]
| | |- XGRS_DEFINITIONS.TXT XGRS Inst. Definitions
|
|- [CATALOG]
| |- CATINFO.TXT Catalog directory information
| |- INSTHOST.TXT Instrument design information
| |- MISSION.CAT NEAR Mission related information and refs
| |- PERSON.CAT Personnel associated with this submission
| |- REF.CAT References to other publications
| |- GRSL2DS.CAT Description of this GRS dataset
| |- GRSINST.CAT Instrument related Information
|
7. Whom To Contact For Information
_______________________________
For questions concerning this data set collection:
Planetary Data System (PDS)
Small Bodies Node (SBN)
Astronomy Department
University of Maryland
College Park, MD 20742
NEAR/XGRS Science Team
Code 691, Astrochemistry Branch
NASA / Goddard Space Flight Center
Greenbelt, MD 20771
WWW Site: http://leptpm.gsfc.nasa.gov/near.html
Electronic mail addresses: jack.trombka@gsfc.nasa.gov,
tim.mcclanahan@gsfc.nasa.gov
8. Cognizant Persons
_________________
NEAR/XGRS data were provided by Jacob Trombka, NEAR XGRS Team Leader:
Jacob Trombka
Building 2, Rm# 165
Code 691, Astrochemistry Branch
NASA/Goddard Space Flight Center
Greenbelt, MD 20771.
jack.trombka@gsfc.nasa.gov
301-286-5941
This volume was designed and produced by:
Tim McClanahan
Building 2, # 166
Code 691, Astrochemistry Branch
NASA/ Goddard Space Flight Center
Greenbelt, MD 2077