Third Cambridge Catalogue of Radio Sources

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.

Third Cambridge Catalogue of Radio Sources
Alternative names3C



It was published in 1959 by members of the Radio Astronomy Group of the University of Cambridge. References to entries in this catalogue in the scientific literature use the prefix 3C followed by the entry number, with a space, e.g. 3C 273. 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 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. E.g. 3C 323.1 follows 3C 323 in Right Ascension and precedes 3C 324.


A further revision by Laing, Riley and Longair in 1983, called 3CRR or 3CR², 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 on the Northern Hemisphere 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. 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 3C 66B is part of the sample, but the BL Lac object 3C 66A is not.

See also

  • Category:3C objects


  • Edge, DO; Shakeshaft, JR; McAdam, WB; Baldwin, JE; Archer, S (1959). "A survey of radio sources at a frequency of 159 Mc/s". Memoirs of the Royal Astronomical Society. 68: 37. Bibcode:1959MmRAS..68...37E.
  • Bennett, AS (1962). "The preparation of the revised 3C catalogue of radio sources". Monthly Notices of the Royal Astronomical Society. 125: 75. Bibcode:1962MNRAS.125...75B. doi:10.1093/mnras/125.1.75.
  • Laing, RA; Riley, JM; Longair, MS (1983). "Bright radio sources at 178 MHz - Flux densities, optical identifications and the cosmological evolution of powerful radio galaxies". Monthly Notices of the Royal Astronomical Society. 204: 151. Bibcode:1983MNRAS.204..151L. doi:10.1093/mnras/204.1.151.

External links


3C may refer to:

In astronomy:

3C, the Third Cambridge Catalogue of Radio Sources, an astronomical reference seriesIn business:

Long March 3C, a 2008 Chinese orbital rocket

3C Records, a record label

3C (radio), a defunct digital radio station

Team 3C Casalinghi Jet Androni Giocattoli, a defunct Italian professional cycling team

3C, the IATA code for defunct American airline RegionsAirIn computing:

Three Cs (Compulsory, Capacity, and Conflict), three categories of CPU cache misses

3C, or Computer Control Company, Inc., a pioneering minicomputer company (1953–1966)

Agile model: 3C (Card, Conversation, Confirmation)

3C, an abbreviation often used in Taiwan for "computer, communication, and consumer electronics"In genetics:

Alpha-tubulin 3C, a human gene

3C, or Chromosome conformation capture, a technique used in molecular biologySubstituted amphetamines (2C family analogues):

3C-G (Ganesha) with homologues



3C-EIn places:

Stalag III-C, a German Army World War II POW camp for Allied soldiers near Alt-Drewitz


3CR may refer to:

3CR (Melbourne), a community radio station, broadcasting on the AM band in Melbourne, Australia

3 Colours Red, a hard rock band

BBC Three Counties Radio, a local radio station in England

Third Cambridge Catalogue of Radio Sources, the revised third Cambridge catalogue of astronomical radio sources


3CRR may refer to:

Third Cambridge Catalogue of Radio Sources, revised edition

Radio station 107.9 ABC Ballarat, callsign 3CRR

3C 286

3C 286, also known by its position as 1328+307 (B1950 coordinates) is a quasar at redshift 0.8493 with a radial velocity of 164,137 km/s. It is part of the Third Cambridge Catalogue of Radio Sources.

3C 286 is one of four primary calibrators used by the Very Large Array (along with 3C 48, 3C 138, and 3C 147). Visibilities of all other sources are calibrated using observed visibilities of one of these four calibrators.

3C 295

3C 295 is a narrow-line radio galaxy located in the constellation of Boötes. With a redshift of 0.464, it is approximately 5 billion light-years from Earth. At time of the discovery of its redshift in 1960, this was the remotest object known.

3C 48

3C48 is a quasar discovered in 1960; it was the second source conclusively identified as such.3C48 was the first source in the Third Cambridge Catalogue of Radio Sources for which an optical identification was found by Allan Sandage and Thomas A. Matthews in 1960 through interferometry.Jesse L. Greenstein and Thomas Matthews found that it had a redshift of 0.367, making it one of the highest redshift sources then known.

It was not until 1982 that the surrounding faint galactic "nebulosity" was confirmed to have the same redshift as 3C48, cementing its identification as an object in a distant galaxy. This was also the first solid identification of a quasar with a surrounding galaxy at the same redshift.

3C 48 is one of four primary calibrators used by the Very Large Array (along with 3C 138 and 3C 147, and 3C 286). Visibilities of all other sources are calibrated using observed visibilities of one of these four calibrators.

Cambridge Catalogue of Radio Sources

The Cambridge Catalogue of Radio Sources may refer to:

First Cambridge Catalogue of Radio Sources

Second Cambridge Catalogue of Radio Sources

Third Cambridge Catalogue of Radio Sources

Fourth Cambridge Survey

Fifth Cambridge Survey of Radio Sources

Sixth Cambridge Survey of radio sources

Seventh Cambridge Survey

Eighth Cambridge Survey

Ninth Cambridge survey at 15GHz

Cassiopeia A

Cassiopeia A (Cas A) is a supernova remnant (SNR) in the constellation Cassiopeia and the brightest extrasolar radio source in the sky at frequencies above 1 GHz. The supernova occurred approximately 11,000 light-years (3.4 kpc) away within the Milky Way. The expanding cloud of material left over from the supernova now appears approximately 10 light-years (3 pc) across from Earth's perspective. In wavelengths of visible light, it has been seen with amateur telescopes down to 234mm (9.25 in) with filters.It is estimated that light from the stellar explosion first reached Earth approximately 300 years ago, but there are no historical records of any sightings of the supernova that created the remnant. Since Cas A is circumpolar for mid-Northern latitudes, this is probably due to interstellar dust absorbing optical wavelength radiation before it reached Earth (although it is possible that it was recorded as a sixth magnitude star 3 Cassiopeiae by John Flamsteed on August 16, 1680). Possible explanations lean toward the idea that the source star was unusually massive and had previously ejected much of its outer layers. These outer layers would have cloaked the star and re-absorbed much of the light released as the inner star collapsed.

Cas A was among the first discrete astronomical radio sources found. Its discovery was reported in 1948 by Martin Ryle and Francis Graham-Smith, astronomers at Cambridge, based on observations with the Long Michelson Interferometer. The optical component was first identified in 1950.Cas A is 3C461 in the Third Cambridge Catalogue of Radio Sources and G111.7-2.1 in the Green Catalog of Supernova Remnants.

Hercules A

Hercules A is a bright astronomical radio source within the vicinity of the constellation Hercules corresponding to the galaxy 3C 348.

Hyron Spinrad

Hyron Spinrad (February 17, 1934 – December 7, 2015) was an American astronomer. His research has ranged from the study of planet atmospheres to the evolution of galaxies. From 2010 until his death in late 2015 he was an emeritus professor of astronomy at the University of California, Berkeley.

Index of physics articles (T)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.


The jansky (symbol Jy, plural janskys) is a non-SI unit of spectral flux density, or spectral irradiance, used especially in radio astronomy. It is equivalent to 10−26 watts per square metre per hertz.

The flux density or monochromatic flux, S, of a source is the integral of the spectral radiance, B, over the source solid angle:

The unit is named after pioneering US radio astronomer Karl Guthe Jansky and is defined as


Since the jansky is obtained by integrating over the whole source solid angle, it is most simply used to describe point sources; for example, the Third Cambridge Catalogue of Radio Sources (3C) reports results in janskys.

List of astronomical catalogues

An astronomical catalogue 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. Astronomical catalogs are usually the result of an astronomical survey of some kind.

Martin Ryle

Sir Martin Ryle (27 September 1918 – 14 October 1984) was an English radio astronomer who developed revolutionary radio telescope systems (see e.g. aperture synthesis) and used them for accurate location and imaging of weak radio sources. In 1946 Ryle and Derek Vonberg were the first people to publish interferometric astronomical measurements at radio wavelengths. With improved equipment, Ryle observed the most distant known galaxies in the universe at that time. He was the first Professor of Radio Astronomy at the University of Cambridge, and founding director of the Mullard Radio Astronomy Observatory. He was Astronomer Royal from 1972 to 1982. Ryle and Antony Hewish shared the Nobel Prize for Physics in 1974, the first Nobel prize awarded in recognition of astronomical research. In the 1970s, Ryle turned the greater part of his attention from astronomy to social and political issues which he considered to be more urgent.

Radio surveys
Cambridge Radio Surveys
Very Large Array
Extragalactic sources
Galactic surveys

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