New comet Bradfield (mag 3 now!)
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COMET BRADFIELD, C/2004 F4
William A. Bradfield of Yankalilla, South Australia, has discovered a comet
in the constellation Cetus. 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 this morning by Daniel W. E.
Green of the Central Bureau for Astronomical Telegrams (
http://cfa-www.harvard.edu/iau/cbat.html) on IAU Circular 8319.
Green's calculations show that the comet will move even closer to the Sun,
both in space and as seen from Earth, until the third week of April. It
reaches perihelion on the 17th, when it will be 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 will be totally
impossible to observe for a week or more except via the SOHO Web site (
http://sohowww.nascom.nasa.gov/data/realtime-images.html), primarily in the
LASCO C3 images. It passes 2.6 degrees from the Sun's center on April 18th.
Toward the end of the month Comet Bradfield emerges in the predawn sky for
skywatchers in midnorthern latitudes. While rapidly fading, it may become
visible in binoculars then.
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.
The following ephemeris is based on Green's very preliminary orbital
elements. For 0 hours UT on each date, it lists the comet's right ascension
and declination (equinox 2000.0), distance from Earth (Delta) and the Sun
(r) in astronomical units, elongation angle from the Sun, approximate
visual magnitude, and constellation. The last column, "optimum latitude"
for viewing, indicates the comet is only visible from the Southern
Hemisphere before the mid-April invisibility period. Thereafter, those in
the Northern Hemisphere are favored.
Roger W. Sinnott
Senior Editor
SKY & TELESCOPE
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COMET BRADFIELD, C/2004 F4
2004 RA (2000) Dec Delta r Elong Mag Const OpLat
h m o ' au au o o
Apr 12 2 08.0 -00 41 1.046 0.265 15 3.8 Cet 40S
Apr 13 2 06.6 -00 07 1.005 0.237 14 3.3 Cet 43S
Apr 14 2 04.1 +00 41 0.963 0.212 12 2.9 Cet 46S
Apr 15 2 00.3 +01 52 0.923 0.190 10 2.4 Cet 50S
Apr 16 1 54.9 +03 31 0.886 0.175 8 2.1 Psc 57S
Apr 17 1 48.0 +05 43 0.856 0.169 5 1.9 Psc 70S
Apr 18 1 40.2 +08 23 0.837 0.173 3 1.9 Psc 64S
Apr 19 1 32.3 +11 18 0.830 0.186 4 2.1 Psc 02S
Apr 20 1 25.0 +14 12 0.833 0.206 7 2.5 Psc 17N
Apr 21 1 18.9 +16 57 0.845 0.231 10 2.9 Psc 24N
Apr 22 1 13.8 +19 28 0.862 0.258 13 3.3 Psc 28N
Apr 23 1 09.7 +21 44 0.883 0.287 16 3.7 Psc 30N
Apr 24 1 06.5 +23 47 0.905 0.316 18 4.0 Psc 31N
Apr 25 1 04.0 +25 37 0.930 0.346 20 4.4 Psc 32N
Apr 26 1 02.1 +27 16 0.955 0.375 22 4.7 Psc 33N
Apr 27 1 00.6 +28 46 0.980 0.405 24 5.0 Psc 33N
Apr 28 0 59.6 +30 08 1.005 0.434 25 5.3 Psc 34N
Apr 29 0 58.9 +31 24 1.031 0.462 26 5.6 Psc 34N
Apr 30 0 58.4 +32 33 1.056 0.491 27 5.8 Psc 34N
May 01 0 58.2 +33 37 1.081 0.519 28 6.0 Psc 35N
May 02 0 58.2 +34 37 1.106 0.546 30 6.2 And 35N
May 03 0 58.3 +35 33 1.130 0.573 30 6.5 And 35N
(If the columns of the table don't line up properly, switch to
a fixed-space font like Courier.)
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