The Third Cambridge Catalogue of Radio Sources (3C) is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz. It was published in 1959 by members of 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, e.g. 3C273. The catalogue was produced using 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 (often called Cambridge University, or just Cambridge), located in Cambridge, England, 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 Telescope, 5km Ryle Telescope, and the Arcminute Microkelvin Imager. ... 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 (MCMLIX) was a common year starting on Thursday of the Gregorian calendar. ... The Cavendish Astrophysics Group (formerly the Radio Astronomy Group) is based at the Cavendish Laboratory at Cambridge University. ... The University of Cambridge (often called Cambridge University, or just Cambridge), located in Cambridge, England, 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). ... Map of the Cambridgeshire area (1904) The city of Cambridge is an old English university town and the administrative centre of the county of Cambridgeshire. ... The Second Cambridge Catalogue of Radio Sources (2C) was published in 1955 by John R Shakeshaft and colleagues. ...

The catalogue was subsequently revised by Bennett in 1962 using observations at 178 MHz, 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 9 Jy 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 3C323.1 follows 3C323 in Right Ascension and precedes 3C324. In radio astronomy, the flux unit or jansky (symbol Jy) is a non-SI unit of electromagnetic flux equivalent to 10−26 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. ...

A further revision by Laing, Riley and Longair in 1983 included galaxies which were not detected in the original catalogue due to shortcomings of the original observations, but which otherwise meet the flux and declination limits. This new catalogue, which includes all extragalactic radio sources with 178-MHz flux density > 10.9 Jy (on the scale of Baars et al), declination greater than 10 degrees, and Galactic latitude greater than 10 degrees or less than -10 degrees, is formally a complete sample of radio galaxies and radio loud quasars, and is sometimes known as 3CRR. It excludes a number of well known 3C/3CR objects, including, of course, all the supernova remnants from 3C, but also some well-known radio galaxies that fall foul of the declination, flux density or galactic latitude constraints. Objects that had been discovered to consist of multiple components associated with different objects were given an alphabetical suffix (A, B...) to make it clear which component was part of the sample: e.g. the radio galaxy 3C66B is part of the sample, but the BL Lac object 3C66A is not. Julia Riley, a Fellow of Girton College, works at the Cavendish Astrophysics Group, University of Cambridge in the study radio astronomy. ... Malcolm Sim Longair is the Jacksonian Professor of Natural Philosophy (head of the Cavendish Laboratory). ... An active galaxy is a galaxy where a significant fraction of the energy output is not emitted by the normal components of a galaxy: stars, dust and interstellar gas. ... This view, taken with infrared light, is a false-color image of a quasar-starburst tandem with the most luminous starburst ever seen in such a combination. ... A BL Lac object or BL Lacertae object or BL Lac is a type of galaxy with an active galactic nucleus (AGN), making it a type of active galaxy. ...

See also

• Category:3C objects
• Cambridge Radio Surveys: 1C - 2C - 3C - 4C - 5C - 6C - 7C - 8C - 9C
  • 3CR

The Second Cambridge Catalogue of Radio Sources (2C) was published in 1955 by John R Shakeshaft and colleagues. ... The Eighth Cambridge Survey (8C) is an astronomical catalogue of celestial radio sources as measured at 38-MHz. ... 3CR is a community radio station, broadcasting on the AM band in Melbourne, Australia. ...

External links

• The Revised 3C Catalogue of Radio Sources on the internet.
• The 3CRR catalogue 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, 125, 75-86
• Laing R.A., Riley J.M., Longair M.S., 1983, MNRAS, 204, 151