A deep VLA survey at 20 cm of the ISO ELAIS survey regions

We have used the Very Large Array (VLA) in C configuration to carry out a s ensitive 20-cm radio survey of regions of sky that have been surveyed in th e far-infrared (FIR) over the wavelength range 5-200 mu m with ISO (Infrare d Space Observatory) as part of the European Large-Area ISO Sun ey (ELAIS). As usual in surveys based on a relatively small number of overlapping VLA pointings, the flux limit varies over the area surveyed: from a 5 sigma lim it of 0.135 mJy over an area of 0.12 deg(2) to 1.15 mJy or better over the whole region covered of 4.22 deg(2), In this paper we present the complete radio catalogue of 867 sources, 428 of which form a complete sample in the flux range 0.2-1.0 mJy, These regions of sky have previously been surveyed to shallower flux limits at 20 cm with the VLA as part of the VLA D configu ration NVSS (full width at half-maximum, FWHM = 45 arcsec) and VLA B config uration FIRST (FWHM = 5 arcsec) surveys, Our whole survey has a nominal 5 s igma flux limit a factor of 2 below that of the NVSS; 3.4 deg(2) of the sur vey reaches the nominal flux limit of the FIRST survey and 1.5 deg(2) reach es 0.25 mJy, a factor of 4 below the nominal FIRST survey limit. In additio n, our survey is at a resolution intermediate between the two surveys and t hus is well suited for a comparison of the reliability and resolution-depen dent surface brightness effects that affect interferometric radio surveys. We have carried out a detailed comparison of our own survey and these two i ndependent surveys in order to assess the reliability and completeness of e ach. Considering the whole sample, we found that to the 5 sigma nominal lim its of 2.3 and 1.0 mJy, respectively, the NVSS and FIRST surveys have a com pleteness of 96(-3)(+2) and 89(-3)(+2) per cent and a reliability of 99(-2) (+1) and 94(-2)(+2) per cent.