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The EXOSAT Raw data
The EXOSAT raw data were distributed to observers as Final Observation
Tape (FOT) in form of 1600 BPI tape. Starting from 1992 a total
of ~ 8643 tapes (1600 BPI) have been archived in ESRIN/ESA onto optical
disk by the ESIS project, and an exact copy has been given to HEASARC/GSFC
(Greenbelt, MD, USA). The data volume for the entire mission
(all instruments) is 150 Gbyte. At the HEASARC the FOT files have been
placed on line in the
EXOSAT raw data
area on the heasarc.gsfc.nasa.gov machine.
The data were made available from the HEASARC on-line system
in May 1994. An additional shipment of data arrived in September 1994,
and was put on-line in December 1994.
Not all the data could be recover because some of the earliest 1600 BPI
tapes were badly damaged. There are 53 observations for which data
from one (or more) experiment are not available neither in the archive
(see list of missing data).
The FOT data are in their binary native format. HEASARC is
reformatting the EXOSAT raw data to FITS format.
Software for the Raw Data native format:
To analyse the EXOSAT FOT data is recommended to use the EXOSAT Interactive
Analysis (IA) System, This can be obtained from the
EXOSAT archive at ESA
or from the
HEASARC.
An overview of the EXOSAT Interactive Analysis Software appeared in Legacy 6
and p. 26 .
The reformatting of the FOTs in FITS started with the Low Energy Experiments.
The FITS files are available on line in the
EXOSAT data area at the HEASARC
LE data
For each LE (LE1 and LE2) obervation in the EXOLOG database, the corresponding
FOT was translated in FITS file. There are 2221 entries in the EXOLOG marked
as LE1 or LE2 observations, but more than one observation can be included in
the same FOT. These duplicate observations are 218. In addition for 19 out 2221
the FOT is missing. The total number of FOTs processed is 1984
(see list ) for an total
amount of 12.4 Gyg of data (compress size).
Each FOT in FITS format consists in
a variable number of FITS files. The basic files are a
catalog, housekeeping,
orbit and event files. The catalog file gives an overview of the observation
in particular records time periods where valid data were collected.
To each time period of valid data is associated an housekeeping and event file.
On the total number of FOTs processed 85 show errors due to corrupted records
in the FOT (see list ).
Archive organization of the FITS data
The archive of the FITS raw data has been organized in the FTP area
in directories one for each observation which will contain data from
all the instruments operating during that observation.
The directory name is derived from the proposal code and the sequence number
as given in the EXOLOG database. The proposal code has been grouped in 9
categories and associated to a 6 digit number, as in the table.
100000 PV Performance Verification
200000 CAL+TOO+OPS Calibration+Target of Opportunity+Operational Activities
300000 LLX CV+Star
400000 HLX X-ray Binaries
500000 SNR SNR
600000 EXG Normal Galaxy
700000 AGN AGN
800000 CLU Cluster of Galaxies
900000 MIS+DEE miscellaneous and deep fields
The sequence number is added to proposal code number to make the directory
name.
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Page authors: Lorella Angelini Jesse Allen
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Last modified: Saturday, 13-Jun-2020 14:08:35 EDT
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