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COS-B Mission Description

COSBMAPS Catalog

The European Space Agency's satellite COS-B was dedicated to gamma-ray astronomy in the energy range 50 MeV to 5 Gev and carried a single spark chamber telescope with approximately a 20 degree field of view. COS-B operated in a highly eccentric polar orbit with apogee around 90000 km between 17 August 1975 and 25 April 1982. During this operational lifetime, COS-B made 65 observations, 15 of which were devoted to high (>20 deg) galactic latitudes.

This database is a collection of maps created from the 65 COS-B observation files. The original observation files can be accessed within BROWSE by changing to the COSBRAW database. For each of the COS-B observation files, the analysis package FADMAP was run and the resulting maps, plus GIF images created from these maps, were collected into this database. Each map is a 120 x 120 pixel FITS format image with 0.5 degree pixels. The user may reconstruct any of these maps within the captive account by running FADMAP from the command line after extracting a file from within the COSBRAW database.

The parameters used for selecting data for these product map files are embedded keywords in the FITS maps themselves. These parameters are set in FADMAP, and for the maps in this database are set as 'wide open' as possible. That is, except for selecting on each of 4 energy ranges, all other FADMAP parameters were set using broad criteria. To find more information about how to run FADMAP on the raw event's file, the user can access help files within the COSBRAW database or can use the 'fhelp' facility from the command line to gain information about FADMAP.

COSBRAW Catalog

The European Space Agency's satellite COS-B was dedicated to gamma-ray astronomy in the energy range 50 MeV to 5 Gev and carried a single spark chamber telescope with approximately a 20 degree field of view. COS-B operated in a highly eccentric polar orbit with apogee around 90000 km between 17 August 1975 and 25 April 1982. During this operational lifetime, COS-B made 65 observations, 15 of which were devoted to high (>20 deg) galactic latitudes.

The COSBRAW database table is a log of the 65 COS-B observation intervals and contains target names, sky coordinates start times and other information taken from the final COS-B database produced by ESA in 1985. This final database consisted of three basic datasets: `OBSLI`, a dataset describing each observation period, typically a month; `OURLI`, a dataset describing each uninterrupted observation interval, lasting between 10 minutes and 10 hours; and `GAMLI`, a dataset containing records for each accepted gamma-ray photon. These three data sets were combined into FITS format images at NASA/GSFC. The images were formed by making the center pixel of a 1024 x 1024 pixel image correspond to the RA and DEC given in the `OBSLI` file. Each photon's RA and DEC was converted to a relative pixel in the image. This was done by using Aitoff projections. All the raw data from these three COS-B files are now stored in 65 FITS files accessible with BROWSE software in the database COSBRAW. The images can be accessed and plotted using XIMAGE and other columns of the FITS file extensions can be plotted with the FTOOL FPLOT.

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