Bradfield’s 18th Comet

Comet Bradfield
Japanese astrophotographer Sho Endo took this picture of Comet Bradfield just before sunrise on April 24, 2004. He used a digital camera set at ISO 400, a 50-mm lens, and a 27-second guided exposure.
Courtesy Sho Endo.
In late March 2004, William A. Bradfield of Yankalilla, South Australia, discovered a comet in the constellation Cetus, the Whale. He first spotted it low in the western evening sky with his 10-inch reflector on March 23rd and 24th, then lost sight of it until April 8th. The find was announced April 12th by Daniel W. E. Green of the Central Bureau for Astronomical Telegrams on IAU Circular 8319.

Until the third week of April, the comet was close to the Sun, both in space and as seen from Earth. It reached perihelion on the 17th, when it was a scant 0.17 astronomical unit (about 25 million kilometers) from the Sun, well inside Mercury's orbit. Even though perhaps brightening to 2nd magnitude, it was totally impossible to observe for a week or more around the time of perihelion except via the SOHO Web site in the LASCO C3 images. It passed 2.6 degrees from the Sun's center on April 18th. Toward the end of April Comet Bradfield emerged in the predawn sky for skywatchers in midnorthern latitudes and has become visible in binoculars.

SOHO view of Comet Bradfield
Comet Bradfield is plainly visible in this image acquired by SOHO's LASCO C3 coronagraph at 12:54 Universal Time on April 18, 2004. The Sun is in mid-frame, hidden by an occulting disk. Click on the image to see a small movie of the comet racing past the Sun between April 16th and 20th.
Courtesy SOHO
Indefatigable comet hunter Bradfield, now age 76, is credited with numerous other discoveries dating back to 1972. All 18 of these comets bear his name alone, which means he spotted and reported them well ahead of any other observer. But it's been nine years since his last discovery, C/1995 Q1. Born in New Zealand, Bradfield worked many years for the Australian government as a research scientist on rocket-propulsion systems before retiring in the late 1980s.

Use our interactive sky chart to follow
Comet Bradfield
during the first few days of May. The sky is set to 3:30 a.m. on May 1st at 40° north. To adjust the date and time, highlight the month, day, hour, or minute and click the "+" or "-" button. To alter your viewing location, press the "Change" button on the location bar.

The following ephemeris is based on Green's very preliminary orbital elements. For 0 hours Universal Time on each date, it lists the comet's right ascension and declination (equinox 2000.0), elongation angle from the Sun, approximate visual magnitude, and constellation. Note that in late April, observers in the Northern Hemisphere are favored.

Comet Bradfield C/2004 F4
(0h UT)
R.A. (2000)
h   m
°   '
Apr. 25 1 04.0 +25 37 20 4.4 Psc
Apr. 27 1 00.6 +28 46 24 5.0 Psc
Apr. 29 0 58.9 +31 24 26 5.6 Psc
May   1 0 58.2 +33 37 28 6.0 Psc
May   3 0 58.3 +35 33 30 6.5 And