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PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
OBJECT = TEXT
INTERCHANGE_FORMAT = ASCII
PUBLICATION_DATE = 2002-07-01
NOTE = "AAREADME.TXT for data set:
NEAR-A-XRS-3-EDR-EROS/ORBIT-V1.0"
END_OBJECT = TEXT
END
NEAR Mission X-RAY SPECTROMETER Level-2 Data Set
========================================================================
1. Introduction
____________
This document provides an overview of the Near Earth Asteroid
Rendezvous X-Ray Level 2 data archives. This volume contains
science data products from observations acquired by the Near
Earth Asteroid Rendezvous (NEAR) X-ray Spectrometer (XRS)
instrument.
The XRS 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. A supporting BROWSE
facility was included to facilitate a high level overview of
asteroid and solar flourescence activity, which is in the form of
time and resolution correlated histographic images of flourescence
detection by the asteroid and solar pointing detectors. Asteroid
surface coverage is included in the form of an image with six
orthogonal views of the asteroid of counts collected by the
asteroid pointing unfiltered detector. The daily images are
integrated through an XRS browser facility XGRSBROWSE.HTML included
in the BROWSE Directory.
2. Documentation
_____________
This document provides an overview of the Near Earth Asteroid
Rendezvous X-Ray Level 2 document archive. These documents
describe the design, development, implementation, calibration and
operations of the NEAR XRS 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 REF.CAT
file in the CATALOG Directory.
Additional documentation is found in the DOCUMENT directory,
including a document describing the XRS instrument calibrations.
3. Observation Log
_______________
This document provides an overview of the Near Earth Asteroid
Rendezvous X-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 XRS
instrument's science 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 configuration information. 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 XRS record
is comprised of the following logical data units:
Spectra: 4, (256 Channel) Spectra (UNF, MG, AL, SOL)
UNF = Unfiltered: Asteroid Pointing
MG = Magnesium: Asteroid Pointing
AL = Aluminum: Asteroid Pointing
SOL = Solar: Sun Pointing
Instrument HouseKeeping: Instrument Rates and activity
Engineering Housekeeping: Engineering Configurations (volts, etc.)
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 XRS Level 2 integral data are BINARY files the describe the
integrated composition of spectral, orbital ephemerides, instrument
configuration and derived products for each XRS 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: x2000011.dat
where x = X-ray Spectrometer
2000 = Year
011 = Day Number
.dat = file extension
For the complete description of the XRS Level-2 Products see:
"The Near Earth Asteroid Rendezvous, X-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. 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.
|
|- [BROWSE] XRS Browse facility - overview of XRS data
|- |- BROWINFO.TXT Description- XRS BROWSE files and system
|- |- MANIFEST.TAB List of files, formats, sizes under BROWSE
|- |- XGRSBROWSE.HTML Home page for Browsing daily images
|- |- XGRSBROWSE.LBL Label file for XGRSBROWSE.HTML file
| |
| |- [COV_MAP] Asteroid Surface Coverage Maps - each day
| | |- XRS_MAP* 6 view image of Asteroid coverage
| | |- from Unfiltered Detector.
| | |- MMM = 3 Char. Month (i.e. JAN = January)
| | |- DD = 2 Char. Day (0-31)
| | |- YYYY= 4 Char. Year (2000 or 2001)
| |
| |- [D_HTML]
| | |- *.HTML HTML files for viewing Daily images during
| | |- low orbit XRS sampling, * = MMM_DD_YYYY
| |
| |- [DAILY_SUMMARY] XRS Daily Ephemerides text summaries
| | |- XRS_SUM*.TXT Daily summar file * = MMM_DD_YYY, as above
| |
| |- [HIST] Hist. images XRS daily Solar, Unfiltered
| |- | detectors.
| | |- [SOLAR] Daily Solar histogram images
| | |- |- XRS_SOL* Solar Histogram image, * = MMM_DD_YYY.JPG
| | |
| | |- [UNFIL] Daily Unfiltered Histogram images
| | |- |- XRS_UNF* Unfil. Hist. image, * = MMM_DD_YYYY.JPG
|
|- [DATA]
| |- DATAINFO.TXT Description - files in the DATA directory
| |
| |- 200001 Jan 2000 Month Reference Dir
| | |- X2000011.* Daily Spectra Set,X=XRS,2XXX=yr, NNN=daynumber
| |
| |- 200002 Feb 2000 Month Reference Dir
| | |- X2000032.* Daily Spectra Set,X=XRS,2XXX=yr,NNN=daynumber
| |
| | .......... All months 2000 to Feb 2001
| |- 200102 Feb 2001 Month Reference Dir
| | |- X2001043.* Daily Spectra Set,X=XRS,2XXX=yr,NNN=daynumber
| |
|
|- [DOCUMENT] XRS Documentation file.
| |- DOCINFO.TXT Description- files in DOCUMENT directory.
|- |- XRS_REQS_7_2.DOC NEAR-XRS L-2 Requirement Specs (MS Word)
|- |- XRS_REQS_7_2.LBL Label file for XRS L-2 Reqs Doc versions
|- |- XRS_REQS_7_2.TXT Reduced form NEAR XRS Reqs specs. (ASCII)
|- |- XRS_REQS_7_2.JPG Reqs. saved as multi-page Jpeg file.
|- |- XRS_REQS_7_2.TIF Reqs. saved as multi-page TIF file.
|- |- XRS_REQS_7_2_*
| |- Individual Pages, NEAR XRS 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* Observation Log and config parms
| | |- XGRS_INST_USER_GUIDE4* Command, CAS generation instructs
| | |- XGRS_OBSLOG* Actual XGRS observ. + command log
| |
| |
| |- [INSTRUMENT]
| | |- XGRS_DEFINITIONS.TXT XGRS Instrument 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
| |- XRSL23DS.CAT Description of this GRS dataset
| |- XRSINST.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/XRS 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
timothy.mcclanahan@gsfc.nasa.gov
301-286-6748