RASSBSC - ROSAT All-Sky Survey: Bright Sources
The ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, revision
1RXS) has been released and is available through the World Wide Web
and via anonymous ftp (ftp://ftp.xray.mpe.mpg.de/rosat/catalogues/rass-bsc/)
(cf. IAU Circular No. 6420, June 19, 1996).
This catalogue is derived from the all-sky survey performed during the
first half year of the ROSAT mission in 1990-1991; 18,811 sources are
catalogued, with a limiting ROSAT PSPC countrate of 0.05 cts/s in the
energy band 0.1- 2.4 keV. 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 (8547 sources) the catalogue represents a sky coverage of
For each source are provided the ROSAT name, the position in equatorial
coordinates, the positional error, the source countrate and error, the
background countrate, exposure time, hardness-ratios HR1 and HR2 and
errors, extent and likelihood of extent, and likelihood of detection.
For 94 percent of the sources, visual inspection confirmed the results
of the standard processing with respect to existence and position; the
remaining 6 percent were reanalyzed and appropriately flagged.
Broadband images are available for a subset of the flagged sources.
Questions or comments about the content of this catalogue may be directed to
Rosat All-Sky survey Catalog source name.
Right Ascension 1950 coordinates
Declination 1950 coordinates
The source RA (displayed at the current equinox year).
The source Dec (displayed at the current equinox year).
The requested Galactic longitude.
The requested Galactic latitude.
The error on the position given in arcseconds. (This includes a 6-arcsecond
The new data flag is a 4-character string composite of 4 flags (RIV?), each
indicating additional screening criteria.
R: sorce counts and extracted radius Recalculated
I: broad band Image available (Note images are not available at HEASARC)
V: variability flag (not yet filled)
?: dummy flag
Each character (flag) in the string can have the following values:
'T' for true, 'F' or '_' for false and '.' for 'not used'.
Source count rate vignetting corrected.
The error on count rate vignetting corrected. If this field is set
to zero, that means the error has not been determined.
The background count rate, vignetting corrected, in counts/sec/arcmin^2.
The exposure time of field given in seconds.
The hardness ratio defined as HR1=(B-A)/(B+A),
where A are the counts in the PHA range 11-41 and B are the counts
in the PHA range 52-201.
Hardness Ratio 1 Error
The hardness ratio defined as HR2=(D-C)/(D+C),
where C are the counts in the PHA range 52-90 and D are the counts
in the PHA range 91-201.
Hardness Ratio 2 Error
The amount is specified, by which the source image exceeds the point spread
function. The value is given in arcsec.
The likelihood of source extent. If > 9999.9, set to 9999.
The likelihood of source detection algorithm. If > 9999.9,
set to 9999.
The source extraction radius in arcsec. If > 9999.9
(e.g. Vela SNR!), set to 9999.
The priority flag is a string composite of 6 characters, each
indicating the following flags:
Sliding window detection history using either the background map (M)
or the local backgroumnd (B) ) = no detection, 1 = detection
PHA Range with Highest Detection Likelihood
The telescope vignetting correction (1=on-axis lower than 1 off-axis)
Date when source was included.
format :yymmdd; 000000: removed
Date when source properties were changed.
format :yymmdd; 000000:not changed
Identification number of SASS field.
An overview of the field structure is available at URL
SASS source number (MASOL number) in SASS field.
Questions regarding the RASSBSC database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
page or mail email@example.com