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HRASSCAT - Hamburg/RASS Catalog: X-Ray Sources



This table is a representation of part of the Hamburg/ROSAT All-Sky Survey (RASS) Catalog (HRC) of optical identifications of X-ray sources at high-galactic latitude, namely the list of X-ray sources. (The list of proposed and possible optical counterparts is given in the linked Browse table HRASSOPTID). The HRC includes all X-ray sources from the ROSAT Bright Source Catalog (RASS-BSC) with galactic latitude |b| >= 30 degrees and declination Dec >= 0 degrees. In this part of the sky covering ~10,000 square degrees, the RASS-BSC contains 5341 X-ray sources. For the optical identification, the HRC authors used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC, an identification could be given. For the rest, either no counterpart was visible in the error circle, or a plausible identification was not possible. With ~42%, AGN represent the largest group of X-ray emitters, ~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources, no object was visible on the blue direct plates within 40" around the X-ray source position. The catalog has been used as a source for the selection of (nearly) complete samples of the various classes of X-ray emitters.

Catalog Bibcode



The Hamburg/RASS Catalogue of optical identifications.
Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources.
    Zickgraf F.-J., Engels D., Hagen H.-J., Reimers D., Voges W.
   <Astron. Astrophys. 406, 535 (2003)>


This table was produced by the HEASARC in February 2005 based on the CDS Catalog table J/A+A/406/353/x-ray.dat.


This table is the Version 3.0 of the HRC, issued on May 6, 2003, and containing 5341 X-ray sources from the ROSAT-BSC. Version 2.0, issued on January 5, 1998 had 4665 positions (Bade et al., 1998, CDS Cat. <J/A+AS/127/145>). Version 1.1, issued on December 5, 1996, had additional entries in the X-ray rows (flags and the date of last change). Version 1.0 was issued on November 1, 1996.

The catalog can be used for scientific purposes if the paper listed in the References section is referenced. For more detailed information about the identification code and the classification scheme for objective prism spectra, the catalog user is also referred to this paper.


The ROSAT project is supported by the Ministerium fuer Bildung, Wissenschaft, Forschung und Technologie (BMBF/DARA) and by the Max-Planck-Gesellschaft (MPG).

The research on which this table is based made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. It has been funded by the Deutsche Forschungsgemeinschaft under Re 353/22-1 to 4 and by the BMBF under DARA 50 0R 96016.

The STScI Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions. The National Geographic Society - Palomar Observatory Sky Atlas (POSS-I) was made by the California Institute of Technology with grants from the National Geographic Society.


The 1RXS catalog designation.

The RASS PSPC count rate, in counts/s.

The error in the RASS PSPC count rate, in counts/s.

The hardness ratio, HR1, of the X-ray source, defined as

            HR1 = (B - A)/(B + A)
where A is the count rate in the 0.11 - 0.41 keV energy band and B is the count rate in the 0.52 - 2.01 keV energy band.

The error in the hardness ratio, HR1.

The hardness ratio, HR2, of the X-ray source, defined as

            HR2 = (D - C)/(D + C)
where C is the count rate in the 0.52 - 0.90 keV energy band and D is the count rate in the 0.91 - 2.01 keV energy band.

The error in the hardness ratio, HR2.

The X-ray source extension, in arcseconds.

The X-ray source extension likelihood.

The RASS designation, RX JHHMM.m+DDMM, as used in the first Version of this catalog.

The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates and to a precision of 0.1 seconds of time in the originating CDS table.

The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates and to a precision of 1 arcsecond in the originating CDS table.

The Galactic Longitude of the X-ray source.

The Galactic Latitude of the X-ray source.

The nominal X-ray source 90% error radius in arcseconds as provided by the SASS processing.

An internal identifying number for the X-ray source in the Hamburg-RASS Catalog Data Base. Every X-ray source in the catalog has a unique values of the Sequence_Number parameter.

An identification code defined as follows: the first (and third) digit(s) give(s) the type classification:

      1      AGN
      2      Galaxy, derived from the morphology on the direct plates
      3      Galaxy Cluster
      5      M Star
      6      White Dwarf
      7_1    K Star
      7_2    F or G Star
      7_3    Cataclysmic Variable (CV)
      7_4    Bright Star (B < 13)
      8      No (unambiguous) identification, overlaps
      803    No spectrum available for likely counterpart
      0      No objects visible within a radius of 40 arcsec around the
             X-ray position ("blank field")
The second digit in the identification code describes the reliability of the given identification:
      0  'highly probable', The proposed counterpart fulfills all requirements
         of its class and no other plausible counterpart within the error radius
         of the X-ray source exists

      1  'probable', The proposed counterpart fulfills the requirements of
         its class, but there are limitations. Either, the objective spectrum
         is  not typical, or there are small conflicts with the X-ray
         information (spectral or spatial information, distance to the
         X-ray position) or there is another (considerably less) plausible
         counterpart in the error circle

      2  'possible', The proposed counterpart fulfills some requirements of
         its class, but there are doubts arising from insufficient objective
         prism data, conflicting X-ray data or another plausible candidate
Thus, ID_Code = 711 implies that the object is a 'probable' K star.

A flag that, if set to 1, means that the identification has changed since the last catalog version.

A flag that, if set to 1, indicates that the X-Ray position has changed since the last catalog version.

A flag that is set to 1 for supplementary X-ray positions.

The date of the last change to any of the fields for the specified X-ray source. According to the CDS ReadMe file for this catalog, for the source 1RXS J123516.9+233447, the last digit of the date was missing, and was replaced by 0. in their table, while, for the source 1RXS J081929.5+704221, and there are no values for the flags or date parameters.

Contact Person

Questions regarding the HRASSCAT database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 29-Jan-2020 16:34:39 EST