The GB6 catalog of radio sources

The Green Bank 4.85 GHz (lambda approximate to 6 cm) survey was made with the NRAO seven-beam receiver on the (former) 91 m telescope during 1986 November and 1987 October. The final set of sky maps covering the declination band 0 degrees < delta < +75 degrees was constructed with data from both epochs. Its noise and position errors are nearly a factor of 2(1/2) smaller than in the epoch 1987 maps, from which the 87GB catalog of 54,579 sources stronger than S approximate to 25 mJy was extracted. Therefore, we used the new maps to make the GB6 catalog of 75,162 discrete sources with angular sizes phi less than or equal to 10.'5 and flux densities S greater than or equal to 18 mJy. This catalog is available in machine-readable versions with either B1950 or J2000 positions and as a printed book with B1950 positions. The GB6 weighted differential source counts S(5/2)n(S) between 18 mJy and 7 Jy agree well with evolutionary models based on independent data.