The VLA-cosmos survey. I. Radio identifications from the pilot project

We present a catalog of 246 radio sources found in the central 1° of the COSMOS field at 1.4 GHz. The VLA pilot project data have a resolution of 1″.9 × 1″.6 and an rms noise limit of ∼25-100 μJy beam ^-1 covering 0.837 deg ². About 20 radio sources are clearly extended, and most of them appear to be double-lobed radio galaxies. We find evidence for a cluster of seven radio galaxies with an extent of ∼10′ southeast of the COSMOS field center. This VLA pilot project was undertaken to demonstrate the feasibility of wide-field mosaicking at 2″ resolution at 1.4 GHz using the VLA in its A configuration. The seven-point mosaic data were used to develop the techniques necessary for reduction and analysis. These data will provide the initial astrometric frame for the optical (ground-and space-based) data of the COSMOS 2 deg ² survey. In addition, they demonstrate the feasibility of obtaining deep (rms ∼ a few microjanskys) radio imaging of this field at 1.4 GHz, since the brightest radio-emission peak detected within the area covered has a flux density of 13 mJy beam ^-1 and no strong sidelobes from sources surrounding the COSMOS field were detected. Comparison of the number counts with other deep radio surveys shows that the COSMOS field is a representative deep field in the radio domain.