Roger Clifton Jennison
Encyclopedia
Roger Clifton Jennison worked as a radio astronomer at Jodrell Bank
under the guidance of Robert Hanbury Brown
. Jennison made a number of discoveries in the field of radio astronomy
, 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
with V Latham.
, England
in 1922. He was commissioned from RAF aircrew to the Technical Branch-Signals where he developed radar
and microwave
systems using the Magnetron.
. 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
. 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 measurements, and a modified form of this approach ("Self-Calibration") is still used today at radio
, optical and infrared
wavelengths.
at Canterbury
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.
His research interests extended to relativity
, studying paths
of light in rotating systems, and also to studying ball lightning
and water divining.
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.
and was involved in the activities of the Canterbury Arts Council.
He was also a Fellow of the Royal Astronomical Society
, the
Institution of Electrical Engineers
and the Royal Society of Arts
.
Jodrell Bank
The Jodrell Bank Observatory is a British observatory that hosts a number of radio telescopes, and is part of the Jodrell Bank Centre for Astrophysics at the University of Manchester...
under the guidance of Robert Hanbury Brown
Robert Hanbury Brown
Robert Hanbury Brown, AC FRS was a British astronomer and physicist born in Aruvankadu, India. He made notable contributions to the development of radar and he later conducted pioneering work in the field of radio astronomy...
. Jennison made a number of discoveries in the field of radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
, including the discovery of the double nature of radio source Cygnus A
Cygnus A
Cygnus A is one of the most famous radio galaxies, and among the strongest radio sources in the sky.It was discovered by Grote Reber in 1939. In 1951, Cygnus A, along with Cassiopeia A, and Puppis A were the first "radio stars" identified with an optical source, of these, Cygnus A became the first...
(3C
Third Cambridge Catalogue of Radio Sources
The Third Cambridge Catalogue of Radio Sources 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...
405.0) with M K Das Gupta
M K Das Gupta
Mrinal Kumar Das Gupta was a noted Indian astronomer. He was born in erstwhile Barishal district . He received his B.Sc and M.Sc degrees in Physics from Dhaka University in 1944 and 1945 respectively. Later he joined the department of Radio Physics and Electronics of the University of Calcutta as...
and the mapping of Cassiopeia A
Cassiopeia A
Cassiopeia A is a supernova remnant in the constellation Cassiopeia and the brightest astronomical radio source in the sky, with a flux density of 2720 Jy at 1 GHz. The supernova occurred approximately away in the Milky Way. The expanding cloud of material left over from the supernova is now...
with V Latham.
Early life
Roger Jennison was born in GrimsbyGrimsby
Grimsby is a seaport on the Humber Estuary in Lincolnshire, England. It has been the administrative centre of the unitary authority area of North East Lincolnshire since 1996...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in 1922. He was commissioned from RAF aircrew to the Technical Branch-Signals where he developed radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
and microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
systems using the Magnetron.
Radio Astronomy
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 phaseClosure 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...
. 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
The Jodrell Bank Observatory is a British observatory that hosts a number of radio telescopes, and is part of the Jodrell Bank Centre for Astrophysics at the University of Manchester...
. In 1958 he successfully demonstrated its effectiveness at radio wavelengths, but it only became widely used for long baseline radio interferometry
Very Long Baseline Interferometry
Very Long Baseline Interferometry is a type of astronomical interferometry used in radio astronomy. It allows observations of an object that are made simultaneously by many telescopes to be combined, emulating a telescope with a size equal to the maximum separation between the telescopes.Data...
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
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
, optical and infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
wavelengths.
Academic career
Roger Jennison was appointed to the University of KentUniversity of Kent
The University of Kent, previously the University of Kent at Canterbury, is a public research university based in Kent, United Kingdom...
at Canterbury
Canterbury
Canterbury is a historic English cathedral city, which lies at the heart of the City of Canterbury, a district of Kent in South East England. It lies on the 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.
His research interests extended to relativity
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
, studying paths
of light in rotating systems, and also to studying ball lightning
Ball lightning
Ball lightning is an unexplained atmospheric electrical phenomenon. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several metres in diameter. It is usually associated with thunderstorms, but lasts considerably longer than the split-second flash of a...
and water divining.
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
Professor Jennison was a co-founder of the Canterbury Society of Artand was involved in the activities of the Canterbury Arts Council.
He was also a Fellow of the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
, the
Institution of Electrical Engineers
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...
and the Royal Society of Arts
Royal Society of Arts
The Royal Society for the encouragement of Arts, Manufacturers and Commerce is a British multi-disciplinary institution, based in London. The name Royal Society of Arts is frequently used for brevity...
.