New comet Bradfield (mag 3 now!)

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This Is SKY & TELESCOPE's AstroAlert for Comets
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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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