Roger Clifton Jennison
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Third Cambridge Catalogue of Radio Sources : "3C" link correction
'''Roger Clifton Jennison''' ([[18 December]] [[1922]] – [[29 December]] [[2006]]) worked as a radio astronomer at [[Jodrell Bank]] under the guidance of [[Robert Hanbury Brown]]. In the 1950s he developed a new observable for obtaining information about visibility phases in an interferometer when delay errors are present called the [[closure phase]]. He utilised the undergraduate teaching laboratories to perform the first measurements of closure phase at optical wavelengths. Jennison saw greater potential for his technique in radio interferometry, and proposed that it should be tested on a three-element radio interferometer at [[Jodrell Bank]]. In 1958 he successfully demonstrated its effectiveness at radio wavelengths, but it only became widely used for [[Very Long Baseline Interferometry|long baseline radio interferometry]] in 1974. A minimum of three antennas are required. This method was used for the first VLBI measurements, and a modified form of this approach ("Self-Calibration") is still used today at [[radio]], [[optical]] and [[infrared]] wavelengths.
Jennison made a number of discoveries in the field of radio astronomy, including the discovery of the double nature of radio source [[Cygnus A]] ([[Third Cambridge Catalogue of Radio Sources|3C]] 405.0) with [[M K Das Gupta]] and the mapping of [[Cassiopeia A]] with [[V Latham]].
==References==
Roger Jennison, ''[http://ukads.nottingham.ac.uk/cgi-bin/nph-bib_query?bibcode=1958MNRAS.118..276J&db_key=AST A phase sensitive interferometer technique for the measurement of the Fourier transforms of spatial brightness distributions of small angular extent]'', Monthly Notices of the Royal Astronomical Society vol 118 pp 276 1958
{{Jodrell Bank Observatory}}
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[[Category:British astronomers]]
[[Category:1922 births]]
[[Category:2006 deaths]]
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