RASS2MASS ivo://nasa.heasarc/rass2mass NASA/GSFC HEASARC Haakonsen, Rutledge 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Infrared Counterpart 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. 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. This is a service provided by NASA HEASARC . 2009ApJS..184..138H https://heasarc.gsfc.nasa.gov/W3Browse/all/rass2mass.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=rass2mass& GET text/xml 180 99999 true 162.69666667 -88.99777778 0.0333333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=rass2mass GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_rass2mass&Action=More+Options&Action=Parameter+Search&ConeAdd=1 ROSAT 0.0333333333333333 Infrared X-ray public rass2mass ROSAT All-Sky Survey BSC/2MASS PSC Cross-Associations XID II Cat name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable count_rate RASS/BSC Source Count Rate ct/s phot.count;em.X-ray.soft double nullable count_rate_error RASS/BSC Source Count Rate Uncertainty ct/s stat.error;phot.count;em.X-ray.soft double nullable no_id_prob Probability of No Association stat.probability double nullable twomass_name 2MASS/PSC Source Designation meta.id.cross char nullable jmag 2MASS/PSC Source J-Band Magnitude mag phot.mag;em.IR.J double nullable id_prob Probability of Unique Association stat.probability double nullable class Browse Object Classification src.class short nullable simbad_type_rass SIMBAD Source Type of RASS/BSC Source src.class char nullable lii Galactic Longitude degree pos.galactic.lon double nullable bii Galactic Latitude degree pos.galactic.lat double nullable simbad_type_2mass SIMBAD Source Type of 2MASS/PSC Source src.class char nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable