William A. Bradfield

William Ashley Bradfield AM (20 June 1927 – 9 June 2014) was a New Zealand-born Australian amateur astronomer, notable as a prolific amateur discoverer of comets.[3] He gained a world record by discovering 18 comets, all of which bear his name as the sole discoverer.[4]

Bill Bradfield
Born(1927-06-20)20 June 1927
Died9 June 2014(2014-06-09) (aged 86)
NationalityNew Zealand
Alma materUniversity of New Zealand
Known fordiscovering a record 18 comets
ChildrenKatherine, Caroline, and Jennifer[2]
AwardsMember of the Order of Australia, Edgar Wilson Award
Scientific career

His astronomical achievements were summed up by Brian G. Marsden, director emeritus of the IAU's Central Bureau for Astronomical Telegrams: "To discover 18 comets visually is an extraordinary accomplishment in any era, but to do so now is truly remarkable, and I think we can be pretty sure nobody will be able to do it again. And it's all the more astounding that in no case did he have to share a discovery with some other independent discoverer. More than any other recipient, Bill Bradfield outstandingly deserves the Edgar Wilson Award."[2]


Bradfield was born in Levin, New Zealand on 20 June 1927. He grew up on a dairy farm, where his interests in rocketry and astronomy first developed, and when he was 15 he got his first small telescope.[1] He attended the University of New Zealand, where he graduated with a bachelor's degree in Mechanical Engineering.[2] He spent 2 years in England doing a rocket propulsion residency and then in 1953 he moved to Australia, taking up residence in Adelaide, where he worked for the Australian Department of Defence as a rocket propulsion engineer and research scientist until he retired in 1986.[5] This was also where he met Eileen; they were married in 1957, and they went on to have three daughters.[2]

Bradfield joined the Astronomical Society of South Australia (ASSA) in 1970 which fueled his interest, and he started hunting for comets in 1971, using a second-hand telescope which he bought from another ASSA member.[1]

Just over a year and 260 hours of searching later, he was rewarded with finding Comet Bradfield (C/1972 E1). Six comets followed in his first six years, and in 1987 the discovery of his 13th comet made him the most prolific comet-hunter of the 20th century.[6] Eventually his count built to 18 comets after 3500 hours of searching,[7] with the 18th and final comet discovery coming on 23 March 2004 when he was 76 years old.[2]

When Bradfield discovered a comet and communicated it to the International Astronomical Union (IAU), it kicked off worldwide action. Within 14 hours of reporting his 17th comet in 1995, it had been observed by more than 20 observers, including the European Southern Observatory (ESO) 1-meter Schmidt telescope at La Silla, Chile.[8]

Comet C/2004 F4 (Bradfield) from Cactus Flats in NE Colorado, US.

His discoveries were particularly notable because he worked alone to discover them, using old and home-made telescopic equipment.[9] Apart from the 100-year-old lens and modern eyepieces, the remainder of his telescope was homemade, but perfectly suited for hunting comets. He did not use photographic or computerized detection equipment, relying instead on purely visual sweeping across the skies.[7]

Having joined the Astronomical Society of South Australia (ASSA) in 1970, Bradfield served as its President from 1977 to 1979. In 1989 he was appointed an honorary Life Member, and he was inducted into the ASSA Hall of Fame in 2013.[10]

He died on 9 June 2014 after a long illness, at age 86.[3]

Awards and honorsEdit

List of discovered cometsEdit

Number Comet Hours Date Mag
1 C/1972 E1 260 Mar 12.81 10
2 C/1974 C1 306 Feb 12.49 9
3 C/1975 E1 145 Mar 12.45 9
4 C/1975 V2 106 Nov 11.74 10
5 C/1976 D1 57 Feb 19.49 9
6 C/1976 E1 9 Mar 3.778 9
7 C/1978 C1 360 Feb 4.755 8
8 C/1978 T3 75 Oct 10.785 9
9 C/1979 M1 98 Jun 24.417 10
10 C/1979 Y1 67 Dec 24.753 5
11 C/1980 Y1 113 Dec 17.751 6
12 P/1984 A1 384 Jan 7.733 11
13 C/1987 P1 307 Aug 11.437 10
14 P/1989 A3 164 Jan 6.514 12
15 C/1992 B1 129 Jan 31.736 10
16 C/1992 J2 30 May 3.806 10
17 C/1995 Q1 289 Aug 17.410 6
18 C/2004 F4 Mar 23.43 8

Comet: Initial designation of the comet
Hours: Number of search hours for discovery
Date: Discovery date in UT
Mag: Total magnitude (brightness) of comet at discovery[16]


  1. ^ a b c "Since he spotted his 13th comet, Australia's Bill Bradfield has been seeing his name in lights" (Signon required – available from Academic Search Premier, Ipswich, MA.). People. 29 (8). 1988-02-29. p. 73. Retrieved 19 August 2014.
  2. ^ a b c d e Levy, David H. (October 2004). "Harvester of Comets" (Signon required – Available from Academic Search Premier, Ipswich, MA.). Sky & Telescope. 108 (4): 121–122. ISSN 0037-6604. Retrieved 19 August 2014.
  3. ^ a b Eicher, David (16 June 2014). "Guest blog: Comet hunter William Bradfield dies". Astronomy Magazine. Cs.astronomy.com. Retrieved 2014-06-20.
  4. ^ "JPL Small-Body Database Browser search for "Bradfield"". NASA Jet Propulsion Laboratory. Retrieved 19 August 2014.
  5. ^ Sinnott, Roger W. (June 17, 2014). "Bill Bradfield, Comet Hunter Extraordinaire (1927–2014)". Sky and Telescope. Retrieved 19 August 2014.
  6. ^ Eicher, D.J. (February 1988). "Comet Bradfield dazzles backyard observers". Astronomy. 16 (2): 34. Bibcode:1988Ast....16...34V. ISSN 0091-6358.
  7. ^ a b Vlahos, Perry (8 August 2014). "Remarkable achievements of Bill Bradfield, comet hunter". Sydney Morning Herald. p. 29. Archived from the original on 19 August 2014. Retrieved 19 August 2014.
  8. ^ "New Comet Bradfield" (Signon required – Available from Academic Search Premier, Ipswich, MA.). Sky & Telescope. 90 (5): 10. November 1995. ISSN 0037-6604. Retrieved 19 August 2014.
  9. ^ Hoffman, Tony. "Septuagenarian 'Wizard' Finds Bright Comet". Retrieved 16 June 2014.
  10. ^ a b "Vale Bill Bradfield". Astronomical Society of South Australia, Inc. Retrieved 19 August 2014.
  11. ^ "Berenice and Arthur Page Medal". National Australian Convention of Amateur Astronomers. Retrieved 16 June 2014.
  12. ^ "Search Australian Honours". It's an Honour Australia Celebrating Australians. Government of Australia. Retrieved 16 June 2014.
  13. ^ "A Brief History". Astronomical Society of South Australia. Archived from the original on 21 January 2013. Retrieved 16 June 2014.
  14. ^ "Awards". Astronomical Society of South Australia. Retrieved 16 June 2014.
  15. ^ "The Edgar Wilson Award Recipients". IAU Central Bureau for Astronomical Telegrams. Retrieved 16 June 2014.
  16. ^ "Comets Discovered from South Australia". Astronomical Society of South Australia. Retrieved 29 August 2014.