Roger Clifton Jennison
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Roger Clifton Jennison (18 December 1922 – 29 December 2006) worked as a radio astronomer at
Jodrell Bank Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astron ...
under the guidance of
Robert Hanbury Brown Robert Hanbury Brown, AC FRS (31 August 1916 – 16 January 2002) was a British astronomer and physicist born in Aruvankadu, India. He made notable contributions to the development of radar and later conducted pioneering work in the field of ...
. Jennison made a number of discoveries in the field of
radio astronomy Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming f ...
, including the discovery of the double nature of radio source Cygnus A ( 3C 405.0) with M K Das Gupta and the mapping of
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 away within the Milky Way ...
with V Latham.


Early life

Jennison was born in
Grimsby Grimsby or Great Grimsby is a port town and the administrative centre of North East Lincolnshire, Lincolnshire, England. Grimsby adjoins the town of Cleethorpes directly to the south-east forming a conurbation. Grimsby is north-east of Linco ...
,
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, in 1922. His education was at
Clee Grammar School for Boys Matthew Humberstone Church of England School, also known as the Matthew Humberstone School, Matthew Humberstone C of E School, Matthew Humberstone Comprehensive School, MHS and Matty, was a secondary school in Cleethorpes, North East Lincolns ...
. He was commissioned from
RAF The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
aircrew to the Technical Branch-Signals, where he developed
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
and
microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...
systems using the
magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field while ...
.


Radio astronomy

In the 1950s he developed a new observable for obtaining information about visibility phases in an
interferometer Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber op ...
when delay errors are present called the
closure phase The closure phase is an observable quantity in imaging astronomical interferometry, which allowed the use of interferometry with very long baselines. It forms the basis of the self-calibration approach to interferometric imaging. The observable ...
. He performed 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 Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astron ...
. In 1958 he successfully demonstrated its effectiveness at radio wavelengths, but it only became widely used for long baseline radio interferometry in 1974. A minimum of three antennas are required. This method was used for the first
VLBI Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. The ...
measurements, and a modified form of this approach ("Self-Calibration") is still used today at
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
,
optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
and
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
wavelengths.


Academic career

Jennison was appointed to the
University of Kent , motto_lang = , mottoeng = Literal translation: 'Whom to serve is to reign'(Book of Common Prayer translation: 'whose service is perfect freedom')Graham Martin, ''From Vision to Reality: the Making of the University of Kent at Canterbury'' ...
at
Canterbury Canterbury (, ) is a City status in the United Kingdom, cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour, Kent, River Stour. ...
in 1965 and was the first Professor of Physical Electronics at the University. Within a year he established the Electronics Laboratory (later Department of Electronics and now School of Engineering and Digital Arts) at the University. Prior to his appointment at Kent he was Senior Lecturer in Radio Astronomy at Jodrell Bank Observatory and Senior Lecturer in Physics,
Manchester University , mottoeng = Knowledge, Wisdom, Humanity , established = 2004 – University of Manchester Predecessor institutions: 1956 – UMIST (as university college; university 1994) 1904 – Victoria University of Manchester 1880 – Victoria Univer ...
. His research interests extended to relativity, studying paths of light in rotating systems, and also to studying
water divining Dowsing is a type of divination employed in attempts to locate ground water, buried metals or ores, gemstones, oil, claimed radiations (radiesthesia),As translated from one preface of the Kassel experiments, "roughly 10,000 active dowsers in G ...
and
ball lightning Ball lightning is a rare and unexplained phenomenon described as luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the observed phenomenon is reported to last c ...
. With the latter, Jennison reported his personal encounter with the phenomenon as an airline passenger during a flight in March 1963, when a glowing ball of light was created inside the aircraft following a lightning strike.Jennison, R Ball Lightning. ''Nature'' 224, 895 (1969)
/ref> After retirement he was appointed as the emeritus professor of physical electronics at the University of Kent. He died on 29 December 2006. The building which he helped design to house the Electronics Laboratory, now the seat of the School of Engineering and Digital Arts, was named after him by the University of Kent in 2009.


Interest in the arts

Jennison was a co-founder of the Canterbury Society of Art and was involved in the activities of the Canterbury Arts Council. He was also a fellow of the
Royal Astronomical Society (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NGO ...
, the
Institution of Electrical Engineers The Institution of Electrical Engineers (IEE) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. It began in 1871 as the Society of Te ...
and the
Royal Society of Arts The Royal Society for the Encouragement of Arts, Manufactures and Commerce (RSA), also known as the Royal Society of Arts, is a London-based organisation committed to finding practical solutions to social challenges. The RSA acronym is used m ...
. Roger Clifton Jennison's interest in the arts may have been stimulated by his father, George Robert Jennison, who was a well-known portrait painter in his home town of Grimsby and whose work is still on display in Grimsby Town Hall.


References


External links


School of Engineering and Digital Arts (formerly Department of Electronics), University of Kent

A phase sensitive interferometer technique for the measurement of the Fourier transforms of spatial brightness distributions of small angular extent

Canterbury Society of Art
{{DEFAULTSORT:Jennison, Roger 20th-century British astronomers 1922 births 2006 deaths Radio astronomers