The Lake County Astronomical Society

Astronomy Bio...Robert Hanbury-Brown

Jay Bitterman

Robert Hanbury-Brown was born on August 31, 1916 in Aruvankadu, India. After studying engineering at Brighton Polytechnic College (Sussex), he received his BSc degree from the University of London in 1935. In 1936, under great secrecy, he joined the radar research team under the auspices of the Air Ministry with Sir Robert Watson. During World War II he had an active part in the radar research program and was a member of the British Air Commission that worked at the Naval Research Laboratory, Washington DC. Although he was one of Britain's most experienced electronic engineers, he did not publish anything due to the secrecy of his work.

From 1947 to 1949 he was a radar-engineering consultant in partnership with Watson-Watt. In 1949 he joined the staff at the Jodrell Bank Observatory in Cheshire, and commenced to work on research into radio astronomy. Under the direction of Bernard Lovell, Hanbury-Brown actively engaged in using radio methods to investigate the origin of meteor showers. In 1931, Karl Jansky accidentally detected the first radio waves of cosmic origin while investigating a problem in communications for the Bell Telephone Company. While working with C. Hazard, he detected radio waves emanating from M31, the Andromeda nebula, at a distance of 2.2 million light years.

Unfortunately, radio telescopes of the time lacked satisfactory resolution to pinpoint a radio source accurately enough to identify its source through an optical telescope. Three years later Hanbury-Brown and his colleagues devised a radio interferometer that greatly improved resolution. While using it, Hanbury-Brown was able to measured the size of Cassiopeia A and Cygnus A that were sources of very strong radio sources. Now it was possible for Walter Baade and Rudolph Minkowski to relate the more accurate radio locations to their own optical observations, and as a result Cygnus A became the first radio source traced to a definite optical identification even though it had a magnitude of only 17.9.

In 1956 Hanbury-Brown devised a further refinement to radio astronomy by inventing a technique to intensify interferometry. He had previously used the stellar interferometer at Narrabi Observatory (in Australia) to study the sizes of` hotter stars. His early work that was carried out at Jodrell Bank contributed to the development of the 76 m radio telescope that was for a long time the largest steerable radio telescope in the world. Since then other types of radio telescopes have been developed, notably the 300 m dish at Arecibo in Puerto Rico, the 5 km radio telescope at Cambridge (consisting of eight in-line 13 m dishes), and the VLA (Very Large Array) in the United States.

In 1960 he became a Fellow of the Royal Society and was appointed Professor of Radio astronomy at the Victoria University, Manchester, where he continued until 1962. While at Manchester, he figured out a way to minimize the background noise that plagued early radio astronomy. Subsequently he designed an extremely elegant, though complex, intensity interferometer making it possible for radio telescopes to measure the diameters of distant radio sources.

Hanbury-Brown then became Chair of Astronomy at the University of Sydney at Parkes where there was an active radio astronomy observatory. He was among the first astronomers to create a radio map of the sky. This map could be constructed using data that was collected during night and day (unlike optical astronomy, that requires clear night time conditions for observation purposes), and revealed features that were different from those detected using optical telescopes. Besides examining the radio emission from structures within the Solar System and our own Galaxy, he investigated potential emissions from extra-galactic sources.

While still in his mid-70s, he and his wife returned to England and to live in a Hampshire village. In 1991 he wrote his autobiography, Boffin: A Personal Story Of The Early Days Of Radar, Radio Astronomy And Quantum Optics. Robert Hanbury Brown, physicist and astronomer died on January 16 2002.