RBSC-NVSS sample. I.

We cross-identified the ROSAT Bright Source Catalog (RBSC, Cat. <IX/10>) and the NRAO VLA Sky Survey (NVSS, Cat. <VIII/65>) to construct the RBSC-NVSS sample of the brightest X-ray sources (>=0.1 counts/s~10^-12^erg/cm^2^/s in the 0.1-2.4keV band) that are also radio sources (S>=2.5mJy at 1.4GHz) in the 7.8sr of extragalactic sky with |b|>15{deg} and {delta}>-40{deg}. The sky density of NVSS sources is low enough that they can be reliably identified with RBSC sources having rms positional uncertainties >=10".

We used the more accurate radio positions to make reliable X-ray/radio/optical identifications down to the POSS plate limits. We obtained optical spectra for many of the bright identifications lacking published redshifts. The resulting X-ray/radio sample is unique in its size (1557 objects), composition (a mixture of nearly normal galaxies, Seyfert galaxies, quasars, and clusters), and low average redshift [<z>~0.1]