The ROSAT Archive is an implementation of the ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, revision 1RXS) and the ROSAT All-Sky Survey Faint Source Catalogue (RASS-FSC, revision 1RXS).
The RASS-BSC is derived from the all-sky survey performed during the
first half year of the ROSAT mission in 1990/91. 18,811 sources are
catalogued, with a limiting ROSAT PSPC countrate of 0.05 cts/s in
the 0.1-2.4 keV energy band. The sources have a detection likelihood of at
least 15 and contain at least 15 source photons. At a brightness limit
of 0.1 cts/s (8,547 sources) the catalogue represents a sky coverage of
92%. The typical positional accuracy is 30 arcsec.
The RASS-FSC is derived from the all-sky survey performed during the ROSAT mission in the energy band 0.1- 2.4 keV. 105,924 sources are catalogued and represent the faint extension to the RASS bright source catalogue. The sources have a detection likelihood of at least 7 and contain at least 6 source photons. (The likelihood of source detection is defined as L =-ln (1-P) , with P = probability of source detection).