One of the best known results of Cos-B was the
2CG catalogue of point sources (Ref.3).
This early catalogue was based on the selected data from only
30 observations made during the first three years of operation.
It was searched for the presence of discrete, or localised, sources
of gamma radiation under the assumption of a flat, or smoothly
varying background. Thus 25 candidate sources were reported.
In view of the availability of the total mission
data as well as more realistic background models, the interpretation
of these enhancements has evolved rapidly. In the following pages,
reference to the historical designation of the sources
in the 2CG catalogue is adhered to for convenience.
Where to find the data
The COS-B event files are available for world wide access within
They are presently in
and have the following naming convention:
where H is ether N or S depending on whether the declination is
north or south, and NN is a two digit number running from 00 to
64, for all 65 observations. (e.g CB2251S18P41.evt was the 42nd
observation, and the source coordinates are RA 2251 DEC -18). If
you have difficulties with this convention, let us know.
Using the COS-B files
To make use of the COS-B files, copy them to a node which has
FTOOLS installed and then run the F2DHISTO FTOOLS utility to create
the fits image, which can then be read directly with SAOIMAGE.
The COS-B Database - db_cosb:[phot]
All the Cos-B data were subjected to a consistent analysis and
selection process and compiled into a single data-set. The final
database (which is available to the public) contains 200 000 events
in the energy range 50 MeV - 5 GeV. This corresponds to an average
count rate 10 events per sq. deg of observed sky.
Supplied with the database is the full information on sensitivity
which exhibited variations ±25% over 6.8 years. The background
which varied in phase with the solar cycle and with pointing direction
can be taken account of using suitable derived background parameters
supplied with the database (Ref.2).