The First Cambridge Catalogue of Radio Sources (1C) refers to the catalogue listed in the article ''Ryle M, Smith F G & Elsmore B (1950)

MNRAS ''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes letters and papers reporting origina ...

vol 110 pp508-523 "A Preliminary Survey of Radio Stars in the Northern Hemisphere"''

The 1C catalogue listed about 50 radio sources, detected at 3.7 m with a fixed meridian interferometer. According to researchers at the Special Astrophysical Observator

most of the sources from 1C were later recognized to be the effect of confusion, i.e. they were not real objects. The survey was produced using the

Long Michelson Interferometer The Long Michelson Interferometer was a radio telescope interferometer built by Martin Ryle and co-workers in the late 1940s beside a rifle range to the west of Cambridge, England. The interferometer consisted of 2 fixed elements 440m apart to s ...

at the Old Rifle Range in

Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...

in 1950. This device operated primarily at a wavelength of 3.7 metres, with an aperture of 110λ, and was operated using Ryle's

phase switching A phase switch is a device used to increase the discrimination and sensitivity of an interferometer, especially at radio frequencies; an extra half-wave path difference is switched in, at well defined frequency, between the two interfering signal s ...

technique.

Francis Graham-Smith Sir Francis Graham-Smith (born 25 April 1923) is a British astronomer. He was the thirteenth Astronomer Royal from 1982 to 1990 and was knighted in 1986. Biography Education He was educated at Rossall School, Lancashire, England, and attended ...

also used the interferometer to measure the electron density in the ionosphere. The catalogue from this survey is only informally known as the 1C catalogue.

List of sources

:After Ryle, ''et al''. § Intensity is in Watts metres⁻² (c./s.)⁻¹ x 10²⁵ Note that the position can be specified more accurately for sources of small declination, since the nature of the instrument is such as to make the table errors overstated if the axis is not exactly East-West.

Results

The survey found radio sources in close proximity to four of the five major extragalactic nebulae, namely M31, M33, M101 and M51, corresponding to sources 00.01, 01.01, 14.01 and 13.01 respectively. Only M81 had no observed radio source. The isotropy of the sources lead the team to conclude that radio stars were either local phenomena, or extragalactic.

References

1 {{astronomical-catalogue-stub