The 4C catalogue (1,2) lists the positions and flux densities of 4843 radio sources as observed with a transit interferometer of east-west baseline 469 wavelengths at 178 MHz. Sources with angular structure in RA greater than about 1.5' are therefore resolved to some extent and consequently the 4C flux densities of these sources are lower than the true values. In order to (a) provide a source list unaffected by the selection effects of an interferometer, (b) check the diameter corrections applied by Gower (1966) to the 4C logN-logS plot, (c) list some of the 4C sources which appear significantly extended, and (d) estimate the the proportion of sources in the catalogue seriously affected by partial resolution, about 1.5 ster of the region covered by the 4C catalogue has been surveyed with a pencil-beam telescope at 178 MHz.
The telescope employs the technique of aperture synthes in one dimension, the resulting beamwidth to half-power being 23' in RA and 18.4'sec(52^o10-dec) in Dec. The results for a total of 726 sourecs with S_nu > 2.5 Jy are given in Section 2. The ratio, gamma, of the flux density, S_i, setermined by the interferometer to the value, S_T, determined by the pancil-beam system provides a measure of the E-W angular extent of each source.
4CT 1969MNRAS.145..181Caswell & Crowther NOT INCLUDED in Master list.