ROSAT All-Sky Survey/NVSS Bright X-Ray Source Sample

By cross-identifying the RASS (ROSAT All-Sky Survey) Bright Source Catalog (RBSC, <a href="cdsarc.cds.unistra.fr/ftp/cats/IX/10">CDS Catalog IX/10</a>) with the NRAO VLA Sky Survey (NVSS, <a href="cdsarc.cds.unistra.fr/ftp/cats/VIII/65">CDS Catalog VIII/65</a>), the authors have constructed the RBSC-NVSS sample of the brightest X-ray sources (>= 0.1 counts/s ~ 10^-12 erg/cm²/s in the 0.1 - 2.4keV band) that are also radio sources (S >= 2.5 mJy at 1.4 GHz) in the 7.8 sr solid angle of extragalactic sky with galactic latitude |b| > 15 degrees and declination > -40 degrees.

The sky density of NVSS sources is low enough that they can be reliably identified with RBSC sources having rms positional uncertainties >= 10". The authors used the more accurate radio positions to make reliable X-ray/radio/optical identifications down to the POSS plate limits. They obtained optical spectra for many of the bright identifications lacking published redshifts.