Bill Bradfield (right) photographed in about 2004 with Paul Curnow of the Astronomical Society of South Australia. Bradfield’s comet seeker telescope is between them. Photo courtesy Paul Curnow
I am sad to report that Bill Bradfield, the most prolific visual comet discoverer of the 20th century, died on Monday 9 June 2014. Bradfield discovered 18 comets, all visually, and what is most striking is that he was the sole discoverer of all 18. This is most unusual as comets are often reported by more than one observer. Comets are named after their discoverer so that there are 18 comets bearing the Bradfield name.
Born on 20 June 1927, Bradfield grew up on the family farm and went on to study mechanical engineering at the University of New Zealand. Afterwards he accepted a position with the Australian Government as a Department of Defence rocket scientist and moved to an establishment near Woomera in South Australia.
Joining the Astronomical Society of South Australia in 1970, he purchased a telescope based on an old photographic lens of 154 mm width. Using this telescope with its home-built mount he began a search program for comets.
He discovered his first comet after 260 hours of searching spread over 15 months. In a 1985 article he is quoted as saying about this first discovery, “I felt as though I had struck gold. But then I had a week of worry until my find was verified.” The reason for the worry was that the telegram he sent to the International Astronomical Union’s Central Telegram Bureau went astray and took a week to be received. The fear was that someone else would also find the comet in the meantime and manage to claim it first. Fortunately, no one did.
As an observer he worked hard. On clear nights with no Moon he rose at 3 am to drive from his home in the Adelaide suburbs to the Adelaide Hills in search of a dark sky. There setting up his telescope by the roadside, he searched the sky systematically, all the while checking possible objects against star charts. Any likely candidate he watched for 20 minutes to see if it moved in relation to the background stars.
After his first discovery in 1972, Bradfield discovered comets in 1974, 1975, 1976, 1978, 1979, 1980, 1984, 1987, 1989, 1992, 1995 and 2004. The last one was the most difficult to find as there was a gap of nine years without a discovery. All together for the 18 comet discoveries Bradfield spent a total of 3500 hours searching. That is dedication!
Bradfield was widely recognised for his comet discoveries. Among other honours the Astronomical Society of Australia awarded him the Berenice Page Medal in 1981. As well, a minor planet discovered by another famous observer, Carolyn S. Shoemaker, at Palomar Observatory in 1980 was named in his honour as 3430 Bradfield.
Bill Bradfield was one of Australia’s best known and most dedicated amateur astronomers. He will be sorely missed.
Australian comet discoverer Bill Bradfield dies age 86 by Denis Buczynski and Amar Sharma, British Astronomical Association website
Bill Bradfield: Cosmic detective by Louise Gilmore, in Halley in Australian Skies, The Australia Women’s Weekly in cooperation with the Powerhouse Museum, 1985, pp 46-47.