3C may refer to the digital radio station of the same name

The Third Cambridge Catalog of Radio Sources (3C) is an astronomical catalogue of celestial radio sources as measured at 159-MHz. It was published in 1959 by the Radio Astronomy Group of the University of Cambridge. References to entries in this catalogue use the prefix 3C followed by the entry number, with no space perforce. ie. 3C273. The catalogue was produced by the Cambridge Interferometer on the west side of Cambridge. (The interferometer had previously been used for the 2C survey, published in 1955). The Cavendish Astrophysics Group (formerly the Radio Astronomy Group) is based at the Cavendish Laboratory at Cambridge University. ... The University of Cambridge is the second-oldest university in the English-speaking world. ... Mullard Radio Astronomy Observatory is home to a number of large aperture synthesis radio telescopes, including the One-Mile and 5km instruments. ... An astronomical catalog is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. ... 1959 was a common year starting on Thursday (link will take you to calendar). ... The Cavendish Astrophysics Group (formerly the Radio Astronomy Group) is based at the Cavendish Laboratory at Cambridge University. ... The University of Cambridge is the second-oldest university in the English-speaking world. ... 3C273 is a quasar located in the constellation Virgo. ... The Cambridge Interferometer was a radio telescope interferometer built by Martin Ryle and Antony Hewish in the early 1950s to the west of Cambridge (between the Grange Road football ground and the current Cavendish Laboratory). ... The city of Cambridge is an old English university town and the regional centre of the county of Cambridgeshire. ... The Second Cambridge Catalogue of Radio Sources (2C) was published in 1955 by J R Shakeshaft and colleagues. ...

The Catalogue was subsequently revised by Bennett in 1962, and for many years 3CR was considered as the definitive listing of the brighter radio sources in the Northern Hemisphere. The revision resulted in a number of sources being deleted from the catalogue (as being below the flux limit of 9Jy or as now-resolved blends of adjacent sources) and others being added. To avoid renumbering the existing sources (which were listed in RA order) these new sources were added using a decimal extension. Eg 3CR323.1 follows 3C323 in Right Ascension and precedes 3C324. In radio astronomy, the flux unit or jansky (abbreviation Jy) is a non-SI unit of electromagnetic flux equivalent to watts per square metre per hertz. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ...

External Links

The Third Cambridge Catalog of Radio Sources (http://cdsweb.u-strasbg.fr/viz-bin/Cat?VIII/1A) on the internet.

References

Edge, D. O., Shakeshaft, J. R., McAdam, W. B., Baldwin, J. E., & Archer, S. 1959, Mem. R. Astron. Soc., 68, 37, A survey of radio sources at a frequency of 159 Mc/s

Bennett A S (1962) MNRAS v125, pp75-86