Added to the NEO Confirmation Page as a LINEAR discovery late on
2004 Oct 19 this magnitude +18 object in the morning sky was first confirmed by Andre
Knofel at the Volkssternwarte Drebach Observatory early on Oct 20.
James McGaha at Sabino Canyon Observatory, Tucson recorded it later
the same day. Positions obtained from Great Shefford early on Oct
21st were sent though to the Minor Planet Center with a note that
there was a suspicion that the object was diffuse and with a
possible short tail to the North-West.
A weather system had passed through earlier that day and the
seeing was very poor. The first attempt at recording the object was
with the CCD set to 2x2 binning (with a pixel scale of
3"/pixel) and a total of 10.5 minutes of exposure with the
object 38° above the horizon. It looked possibly diffuse and there
were hints of a tail but not definite enough to be absolutely sure.
Another 8 minutes of exposure were taken starting about 45
minutes after the first run was completed. The object was higher in
the sky, but still the appearance was possibly diffuse but not
40 minutes after the second run had completed a third run was
started, but this time with the CCD set to 1x1 binning (with a pixel
scale of 1.5"/pixel) and by this time the object had risen to
an altitude of 52°. The exposures were kept short (16 seconds) to
minimise any blurring of the image due to imperfections in the
telescope mount and a total of 10mins 40sec exposure was
taken. The resulting image (above) shows a 9" diameter core
with some brightness extending to the North-West (upper right). The
diameter was slightly larger than nearby stars of similar brightness
and the PSF profile was less concentrated than nearby stars (see P/2003
O2 PSF example).
At this point it was decided that it was worth
informing the Minor Planet Center that the object might be a comet. IAUC
8421 announced the comet at 18:09 UT on 2004 Oct 21.
a retrograde orbit with an inclination of 130°, the comet was due
at perihelion during the first week of December 2004 at a distance
of 2.7 AU from the Sun. In the two months after discovery the
distance from Earth would reduce from 2.8 AU at discovery to 1.8 AU
in mid December 2004, both effects causing the comet to brighten significantly.
During the December dark of the Moon it was being reported by visual
observers as bright as mag +13.2.