Radio-loud active galaxies in the northern ROSAT All-Sky Survey .1. Radio identifications

We present 5 GHz high resolution VLA observations of 2,127 radio- and X-ray-emitting sources found in both the Green Bank (GB) 5 GHz radio catalog and the ROSAT All-Sky Survey (BASS). We report core flux densities and positions accurate to +/-0.5''. Combined with the GB measurements of the total radio emission, we derive the core-to-lobe ratio of objects in our sample and discuss their core-dominance relative to samples of radio galaxies and BL Lacertae objects. Our results show the RASS/Green Bank (RGB) sample is approximately an order of magnitude more core-dominated than the radio galaxy sample, but is more than an order of magnitude less core-dominated than highly beamed BL Lacertae objects. Using simple beaming models, this indicates the typical object in the RGB catalog exhibits moderately beamed radio emission and is oriented at an angle to the line-of-sight <(theta)over bar>(RGB) similar to 25 degrees - 35 degrees. The case of the origin of the X-ray emission is not as clear; the data are consistent with either an anisotropic unbeamed or moderately beamed X-ray component. Tables 2 and 3 which present the RGB catalog are available in their entirety only from the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), via the WWW at http://cdsweb.ustrasbg.fr/Abstract.html, or at ftp://ftp.astro.psu.edu/pub/edf.