A 4.85 GHz sky survey. I - Maps covering delta between 0 and + 75 deg

Abstract

The new seven beam receiver and lateral-focus corrector were used on the NRAO 91 m telescope during 1987 October to make a total-power survey of the declination band 0^deg^ < δ < + 75^deg^ at 4.85 GHz. The data were reduced with AIPS to yield sky maps covering 6.0 sr with 3.7 arcmin X 3.3 arcmin resolution (10^6^ beams sr^-1^). The rms map noise is ~5 mJy, about five times greater than the rms confusion level. There are 10^4^ sources sr^-1^ stronger than 25 mJy, and their rms position uncertainties in each coordinate range from 10 arcsec for the stronger sources to 30 arcsec for the weakest sources observed near the Sun. These maps are available on FITS tapes for further analysis, and a list of discrete sources is being prepared. Repeat surveys have been made to reduce the noise level and position uncertainties and to identify variable or transient sources. Future surveys with the NRAO 43 m telescope will extend the sky coverage to the southern hemisphere.