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J/ApJS/184/138  XID II: RASS/BSC-2MASS/PSC cross-association  (Haakonsen+, 2009)
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, 138-151 (2009)>
   =2009ApJS..184..138H
ADC_Keywords: Cross identifications ; Infrared sources ; X-ray sources

Keywords:  catalogs - infrared: general - stars: coronae - X-rays: galaxies
           X-rays: general - X-rays: stars

Abstract:
    The 18806 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 Pid that
    the NIR source and X-ray source are uniquely associated, and the
    probability Pno-id that none of the 2MASS/PSC sources are associated
    with the X-ray source. The catalog includes 3853 high quality
    (Pid>0.98) X-ray-NIR matches, 2280 medium quality (0.98≥Pid>0.9)
    matches, and 4153 low quality (0.9≥Pid>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.
    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 Pid>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 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.

Description:
   Observations of the RASS/BSC (Voges et al., 1999, cat. IX/10) were made in
   1990/91 with the ROSAT/PSPC satellite.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table3.dat       162    18806   Association catalog


See also:
   IX/10  : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
   II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)


Byte-by-byte Description of file: table3.dat

   Bytes Format Units   Label     Explanations

   1-  4  A4    ---     ---       [1RXS]
   6- 21  A16   ---     1RXS      RASS/BSC source name (JHHMMSS.s+DDMMSS)
  23- 65  A43   ---     obj       SIMBAD object type of RASS/BSC source
  67- 72  F6.2  ct/s    xrt       RASS/BSC source count rate
  74- 77  F4.2  ct/s    e_xrt     RASS/BSC source count rate uncertainty
  79- 83  F5.3  ---     P(noid)   Probability of no association (1)
  85- 89  A5    ---     ---       [2MASS]
  91-107  A17   ---     2MASS     ? 2MASS/PSC source name (JHHMMSSss+DDMMSSs)
 109-151  A43   ---     obj2      ? SIMBAD object type of 2MASS/PSC source
 153-156  F4.1  mag     Jmag      ? 2MASS/PSC source J-band magnitude
 158-162  F5.3  ---     P(id)     ? Probability of unique association (1)

Note (1): P(noid)=1/(1+ΣMj=1(Rj/1-Rj_)).
     [See equation (4) in section 2 of the paper for further details]
     Pi(id)=Ri/[(1-Ri)(1+ΣMj=1(Rj/1-Rj_)]. 
     [See equation (3) in section 2 of the paper for further details]. 
     The definitions of P(id) and P(noid) are the same as in the previous
     work (Rutledge et al., 2000ApJS..131..335R).


History:
    From electronic version of the journal

References:
   Rutledge et al. Paper I. 2000ApJS..131..335R.
(End)                 Greg Schwarz [AAS], Emmanuelle Perret [CDS]    08-Feb-2010