The 5 GHz strong source surveys. IV - Survey of the area between declination 35 and 70 degrees and summary of source counts, spectra and optical identifications

Abstract

A new zone (54) has been surveyed at 5 GHz and is essentially complete above 0.5 Jy. A total of 269 sources above this flux density were found in an area of 1.71 sr between declinations of 35 and 70 . Accurate flux densities at 2.7, 5.0, and 10.7 GHz are given, together with source coordinates accurate to between 1 and 5 arcsec, and proposed optical identifications. Sources below the completeness limit are also listed, giving a catalog of 484 sources. The results of the S4 survey are combined with those of the previous 5 GHz surveys, with a 5 GHz strong source sample derived from the Parkes 2.7 GHz surveys, and with samples taken from deeper surveys made at 5 GHz to discuss the source counts, the source spectra and their relation to the optical identifications. The 5 GHz source counts differ from those derived at lower frequencies in that there is less evidence for either a steepening of the counts at high flux densities or for their convergence at very low flux densities. The counts indicate a possible anisotropy related to the superga1actic system.