The 6C survey of radio sources - II. The zone Formula

Abstract

The 6th Cambridge survey of radio sources covers most of the sky north of δ+30° with an angular resolution of 4.2×4.2 cosec δ arcmin2 and reaches a limiting flux density of 190 mJy at 151 MHz in the present zone. In this paper the methods used to produce the survey maps from a non-tracking telescope operating at declinations other than the north celestial pole are described: this forms the basis for all future papers in the series. Maps of a high galactic latitude region |$30^\circ \lt \delta \lt 51^\circ, 08^\text h30^\text m\lt\alpha\lt17^\text h30^\text m$| are presented, together with a list of 8278 sources in the 2030 deg2 covered. A source count over the range 200 mJy<S(151)<100 Jy is derived.