A 1421-MHz survey of radio sources near the North Celestial Pole

A new survey at 1421 MHz of seven regions spaced at 2° intervals about the North Celestial Pole covers an area of 19 deg2 to a depth of 75 mJy and of 2.6 deg2 to a depth of 30 mJy, the resolution being 3.6 arcmin. One hundred and six sources have been found, of which 43 are new. The results of the survey are given here, together with 5-km telescope maps of four of the sources and details of a further 10 new sources > 90 mJy seen near 3C 309 .1. Systematic errors of order 30 arcsec have been found in the positions given in the Ryle & Neville (RN) 178-MHz survey, and so most of the optical identifications previously suggested for RN sources are spurious. It is shown from the source counts and from the distribution of spectral indices selected at 1421 MHz that the region is ‘normal’, while the spectral distribution in a sample selected at 178 MHz closely resembles that found at higher flux densities.