6C Survey Research Articles

The 7C survey of radio sources at 151 MHz — a region covering RA 9h to 16h and Dec. 20° to 35°

The 7C survey of radio sources at 151 MHz — a region covering RA 9h to 16h and Dec. 20° to 35°

The 6C survey of radio sources - VI. The continuous zone 30 < < 51 , 0h < < 09h 05m and 22h 35m < < 24h

This paper complements Paper II of the series on the 6C survey of radio sources, presenting the remainder of the strip 30°<δ<51° which extends the coverage into the regions of lower Galactic latitude at these declinations. The observations made and the data reduction methods and other conventions adopted for the strip are fully described in that paper, details will not be repeated except where they differ or require comment. The data here presented consist of 1 92 pages of maps covering the continuous region 30°<δ<51°, O h <α<09 h 05 m and 22 h 35m<α<24 h ,together with a corresponding list of 6752 sources in the 2440 deg 2 covered

The 6C survey of radio sources - V. The zones $6C-Va Formula

This paper complements Paper III of the series on the 6C survey of radio sources, presenting the remaining parts of the observations of the strip 48° < δ < 68° which extend the coverage into the regions of lower Galactic latitude at those declinations. The observations made and the data reduction methods and other conventions adopted for the strip are described in that paper, details will not be repeated except where they differ or require comment. The data here presented consist of 92 pages of maps covering two regions: 48° < δ < 68°, 01 h 34 m < α < 06 h 14 m and 48° < δ < 68°, 17 h 16 m < α < 20 h 24 m , together with a corresponding list of 3458 sources

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

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.

The 6C survey of radio sources - I. Declination zone Formula

The 6th Cambridge Survey of radio sources covers most of the sky north of |$\delta+30^\circ $| with an angular resolution of |$4.2\times4.2 \,\text{cosec}\, \delta\,\text{arcmin}^{2}$| and a limiting flux density of 120 mJy at 151 MHz. This paper, the first of a series, describes the telescope and the methods used to produce the survey maps and source list, and presents maps of a circular area of radius 10° centered on the North Celestial Pole and a list of 1761 sources north of |$\delta+80^\circ $|⁠.

A sample of 6C radio sources selected at the peak of the source counts - I. A search for extended sources and multifrequency radio observations

The selection of a sample of 67 faint radio sources from the 6C survey is described, including a search for extended sources on the 6C maps to ensure the completeness of the sample. Forty-two of the sources are in the '1 Jy' sample by Allington-Smith and so already have high-resolution radio observations. This paper describes high-resolution observations of the remaining 25, as well as low-frequency observations of sources in the 1-Jy sample. The radio observations of the 6C sources, when considered as a whole, reveal a mix of radio structures similar to that of a sample of bright 3C sources, although the median angular size of the 6C sources is 14 arcsec, one third of that for the 3C sample (43 arcsec). The spectral index distributions of the 3C and 6C samples are similar. The radio observations are consistent with the 6C sample being composed of sources which are similar in many ways to those in the 3C sample but at higher redshifts.

Multi-Frequency Polarization Studies of Radio Galaxies

This is a brief report on some of the work in progress at Cambridge, with emphasis on studies of extragalactic radio sources using the One-mile and 5-km telescopes; together with the 6C survey and a new instrument now being commisioned at 151 MHz, we have a frequency range of 100:1 available for high-resolution mapping. The 6C survey has resulted in the discovery of a number of giant radio galaxies, most notably NGC 6251. At 151 MHz, the beautiful jet is not prominent; we have mapped it with the One-mile and 5-km instruments and a paper (by Saunders et al.) will shortly appear in Monthly Notices. Dr Willis will speak later on the structure of this source.

A test of clustering among radio sources in 0.16 sr of the 6C survey

A test of clustering among radio sources in 0.16 sr of the 6C survey

The 6C Survey

A new survey of radio sources at 151 MHz, which has not been described previously, is in progress at Cambridge. There are several of us working on it including Warner, Kenderdine, Waggett, Masson and Mayer. The results of the first observations are at present in a preliminary state but we hope that in time they will form the first part of the 6C survey. The purpose of the survey is not to reach the faintest sources detected so far in aperture synthesis observations but to study moderately faint sources at a low observing frequency and to cover a large part of the northern sky rapidly. The deepest survey made so far at a low frequency is that of Ryle and Neville (1962) at 178 MHz over a region of 50 square degrees near the north celestial pole. The faintest sources detected had flux densities of 0.25 Jy, corresponding to a source density of 104 sr−1. It is already 15 years since that survey, which was the first trial of aperture synthesis using the earth's rotation, and much more is now technically possible. One of the most interesting features of a low frequency survey is its ability to detect preferentially sources with steep radio spectra and to be sensitive to sources of very low surface brightness. We know that in many cases these two properties go together and are associated with old radio sources, or at least with those parts of sources which are old. Many of the weak radio galaxies in nearby clusters are obvious examples of this type of source while the final, and so far unidentified, stages of the development of the most powerful double sources may be exciting candidates for discovery.