The 18,806 ROSAT All Sky Survey Bright Source Catalog (RASS/BSC)
X-ray sources are quantitatively cross-associated with near-infrared (NIR)
sources from the Two Micron All Sky Survey Point Source Catalog (2MASS/PSC).
An association catalog is presented, listing the most likely counterpart for
each RASS/BSC source, the probability P_id (called id_prob in the HEASARC
version of this catalog) that the NIR source and X-ray source
are uniquely associated, and the probability P_no-id (called no_id_prob in
the HEASARC version of this catalog) that none of the 2MASS/PSC
sources are associated with the X-ray source. The catalog includes 3853 high
quality (P_id>0.98) X-ray-NIR matches, 2280 medium quality (0.98 >= P_id > 0.9)
matches, and 4153 low quality (0.9 >= P_id > 0.5) matches. Of the high quality
matches, 1418 are associations that are not listed in the SIMBAD database, and
for which no high quality match with a USNO-A2 optical source was presented
for the RASS/BSC source in previous work (Rutledge et al. 2000, ApJS, 131,
335). The present work offers a significant number of new associations with
RASS/BSC objects that will require optical/NIR spectroscopy for classification.
For example, of the 6133 P_id > 0.9 2MASS/PSC counterparts presented in the
association catalog, 2411 have no classification listed in the SIMBAD database.
These 2MASS/PSC sources will likely include scientifically useful examples of
known source classes of X-ray emitters (white dwarfs, coronally active stars,
active galactic nuclei), but they may also contain previously unknown source
classes. It is determined that all coronally active stars in the RASS/BSC
should have a counterpart in the 2MASS/PSC, and that the unique association of
these RASS/BSC sources with their NIR counterparts thus is confusion limited.
XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray
Sources with 2MASS Point Source Catalog Near-Infrared Sources.
Haakonsen, C.B., Rutledge, R. E.
<Astrophys. J. Suppl. Ser. 184, 138 (2209)>
This table was created by the HEASARC in October 2009 based on
an electronic version of Table 3 (the 'Association Catalog') from the paper
which were obtained from the Astrophysical Journal web site.
The RASS name of the X-ray source using the recommended '1RXS' prefix
and the J2000 equatorial coordinates of the source.
The Right Ascension of the X-ray source in the selected equinox. This
was constructed (by the HEASARC) from its position-based name.
The Declination of the X-ray source in the selected equinox. This
was constructed (by the HEASARC) from its position-based name
The Galactic Longitude of the X-ray source.
The Galactic Latitude of the X-ray source.
The SIMBAD source type of the RASS/BSC source.
The RASS/BSC X-ray source count rate, in ct/s.
The RASS/BSC X-ray source count rate uncertainty, in
The probability that none of the off-band (2MASS/PSC) sources
within 75 arcseconds of the X-ray source position are associated with the
The 2MASS/PSC near-infrared source designation of the most
likely (highest value of id_prob) counterpart to the X-ray source.
The SIMBAD source type of the 2MASS/PSC source.
The 2MASS/PSC source J-band magnitude of the most
likely (highest value of id_prob) counterpart to the X-ray source
The probability that the most likely off-band (2MASS/PSC) source
is uniquely associated with the X-ray source.
The HEASARC Browse object classification, based on the Simbad type
of the 2MASS source, else on the Simbad type of the RASS source
Questions regarding the RASS2MASS database table can be addressed to the
HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: 9-Oct-2009