This Is SKY & TELESCOPE’s AstroAlert for Comets

NEW COMET IN THE DAWN SKY

Another new comet, even brighter than Comet Hoenig
(announced last week), can now be seen by observers with
large binoculars in the Northern Hemisphere. It is low in
the eastern sky around the time morning twilight begins.

According to calculations by Brian G. Marsden, published
by the Central Bureau for Astronomical Telegrams on IAU
Circular 7948 (August 3rd), this comet will pass through
perihelion around September 9th. It will then be midway
between the Earth's orbit and the Sun. This comet is
traveling in a near-parabolic orbit inclined 59 degrees
to the ecliptic. Further details about the discovery are
available from the Central Bureau's subscription service
(visit http://cfa-www.harvard.edu/iau/cbat.html ).

Unfortunately, as this comet gets closer to perihelion
its elongation angle from the Sun decreases, making it
harder to observe. On August 8th, for example, at the
start of morning twilight, the comet is 16 degrees
above the eastern horizon for an observer at latitude
40 degrees north. By the 21st it is only 10 degrees
above the northeastern horizon as twilight begins.
The second and third weeks of August appear to offer the
best viewing prospects for this object, which is not
likely to become brighter than 6th magnitude.

While it carries the designation C/2002 O6, this comet's
name has not yet been officially announced. Japanese
astronomer Masayuki Suzuki was among the first to spot
it on all-sky images taken in late July with the SOHO
spacecraft's SWAN solar-wind camera. Unlike the many
other SOHO comets, this one was detected 90 degrees from
the Sun and is not a Sun-grazer at all. As reported on
IAU Circular 7944 (August 1st), Alan Hale in Cloudcroft,
New Mexico, confirmed it visually with an 8-inch (20-cm)
telescope and J. Broughton in Queensland, Australia,
obtained CCD images with a 10-inch reflector.

The following ephemeris, based on Marsden's preliminary
orbital elements, gives the comet's right ascension and
declination (equinox 2000.0) at 0h Universal Time on each
date, its distance from the Earth (delta) and Sun (r) in
astronomical units (where 1 a.u. is 149,600,000 km),
elongation angle, predicted magnitude, and the
constellation through which it is passing.


Roger W. Sinnott
Senior Editor
Sky & Telescope


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                      COMET 2002 O6

Date       R.A.    Dec.    delta    r   Elong. Mag. Const.
(0h UT)    h  m     o  '    a.u.   a.u.    o            
Aug 05    4 39.3  -03 09   0.279  0.942   67   7.0   Eri
Aug 06    4 54.4  +00 33   0.270  0.925   63   6.8   Ori
Aug 07    5 10.5  +04 30   0.263  0.908   59   6.7   Ori
Aug 08    5 27.6  +08 35   0.259  0.891   55   6.6   Ori
Aug 09    5 45.5  +12 42   0.258  0.873   51   6.5   Tau
Aug 10    6 04.1  +16 45   0.259  0.856   47   6.4   Ori
Aug 11    6 23.2  +20 36   0.264  0.839   43   6.3   Gem
Aug 12    6 42.5  +24 10   0.271  0.822   39   6.3   Gem
Aug 13    7 01.7  +27 22   0.281  0.805   37   6.3   Gem
Aug 14    7 20.7  +30 10   0.293  0.789   34   6.3   Gem
Aug 15    7 39.1  +32 33   0.307  0.772   33   6.3   Gem
Aug 16    7 56.7  +34 32   0.323  0.755   31   6.3   Lyn
Aug 17    8 13.4  +36 10   0.341  0.739   30   6.4   Lyn
Aug 18    8 29.1  +37 28   0.361  0.723   30   6.4   Lyn
Aug 19    8 43.7  +38 30   0.381  0.707   30   6.4   Lyn
Aug 20    8 57.2  +39 17   0.403  0.691   30   6.4   Lyn
Aug 21    9 09.7  +39 52   0.426  0.676   30   6.4   Lyn
Aug 22    9 21.1  +40 16   0.450  0.661   30   6.5   Lyn
Aug 23    9 31.6  +40 32   0.474  0.646   30   6.5   Lyn
Aug 24    9 41.1  +40 41   0.499  0.631   30   6.5   Lyn
Aug 25    9 49.8  +40 44   0.525  0.617   30   6.5   LMi
Aug 26    9 57.7  +40 40   0.552  0.604   30   6.5   LMi
Aug 27   10 04.9  +40 33   0.579  0.591   31   6.5   LMi
Aug 28   10 11.5  +40 21   0.606  0.578   31   6.5   LMi
Aug 29   10 17.5  +40 06   0.634  0.566   31   6.5   UMa
Aug 30   10 23.0  +39 47   0.662  0.555   31   6.5   UMa
Aug 31   10 28.0  +39 25   0.691  0.545   31   6.6   UMa
Sep 01   10 32.6  +39 01   0.720  0.535   31   6.6   LMi
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SPECIAL NOTE:  Many subscribers reported getting multiple
copies of last week's AstroAlert about Comet Hoenig. We
believe we have traced the problem to a recipient outside
the U.S. and are taking steps to prevent its recurrence.
We apologize for the inconvenience these extra messages
have caused.