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

P. Ciliegi, R. G. McMahon, G. Miley, C. Gruppioni, M. Rowan-Robinson, C. Cesarsky, L. Danese, A. Franceschini, R. Genzel, A. Lawrence, D. Lemke, S. Oliver, J.-L. Puget, B. Rocca-Volmerange

Research output: Contribution to journalArticlepeer-review


We have used the Very Large Array (VLA) in C configuration to carry out a sensitive 20-cm radio survey of regions of sky that have been surveyed in the far-infrared (FIR) over the wavelength range 5--200 μm with ISO (Infrared Space Observatory) as part of the European Large-Area ISO Survey (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 5sigma limit 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 configuration NVSS (full width at half-maximum, FWHM=45 arcsec) and VLA B configuration FIRST (FWHM=5 arcsec) surveys. Our whole survey has a nominal 5sigma flux limit a factor of 2 below that of the NVSS; 3.4 deg^2 of the survey reaches the nominal flux limit of the FIRST survey and 1.5 deg^2 reaches 0.25 mJy, a factor of 4 below the nominal FIRST survey limit. In addition, our survey is at a resolution intermediate between the two surveys and thus is well suited for a comparison of the reliability and resolution-dependent surface brightness effects that affect interferometric radio surveys. We have carried out a detailed comparison of our own survey and these two independent surveys in order to assess the reliability and completeness of each. Considering the whole sample, we found that to the 5sigma nominal limits of 2.3 and 1.0 mJy, respectively, the NVSS and FIRST surveys have a completeness of 96^+2_-3 and 89^+2_-3 per cent and a reliability of 99^+1_-2 and 94^+2_-2 per cent.
Original languageEnglish
Pages (from-to)222-244
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Jan 1999



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