C/2004 Q2 (Machholz), 72P/Denning-Fujikawa, 9P/Tempel 1, C/2005 K1 (Skiff),
and P/2005 JQ5 (Catalina)
The following are the results of observations of Comet Machholz
and others:
Machholz is moving slowly through the Big Dipper. In the
20cm refractor at 60x it appears as a large glow more than 5' in diameter.
In photographs by the 60cm reflector only the sharp nucleus is captured.
Overall, the accuracy of the measurements presented here is high. In early
days it was very difficult to keep errors in positional measurements within
+/-1", but now it is commonly kept within 1" due to improvement
on the stellar catalogues. This level of accuracy is unimaginable to observers
who were active more than 30 yeas ago.
Faint comets have been discovered by LINEAR and those down
to about 20th magnitude are observable. However, faint and fast-moving
comets like C/2005 are very difficult to photograph and definitely in the
domain of observers with CCDs.
Comet Denning-Fujikawa is getting closer to perihelion in
the pre-dawn sky near the sun. I believe Mr. Fujikawa is anxious to recover
his comet, but unfortunately, the observing conditions are not favorable
at all. I provided my own magnitude predictions in the next Comet Bulletin.
It will be difficult to find this comet unless it experiences outbursts.
It has been well over 100 years since this comet was discovered by Denning
in 1881. After the initial discovery it was found only once when it brightened.
This comet rarely brightens and it was miraculous that Mr. Fujikawa encountered
this comet in October 1978. At the next return in 1987 I meticulously searched
using the 60cm reflector, but failed to find it. Comets of this type may
experience a large non-gravitational effect, which makes the recovery increasingly
difficult as time passes.
When I observed the comet following the report of Mr. Fujikawa's
discovery on October 9, 1978, the 10.5-magnitude comet was fuzzy and very
diffused without the nucleus. My prediction on the non-gravitational effect
on this comet is not based on any particular theory. Rather, this comet's
uncommonly diffuse appearance made me remember the image of Comet Perrine-Mrkos.
Perrine-Mrkos brightened occasionally and was found, though not often.
It also shows a large non-gravitational effect.
Comet Tempel 1, which has been in news for the impending
impact by the Impactor on July 4, is visible at 10th-11th magnitude, slightly
off to the south from the zenith in the evening sky. Its positions have
been measured globally, but has not brightened much. This comet, too, had
been lost for many years and the recovery by Dr. E. Roemer after 90 years
amazed us. Since then, this comet appears regularly in a 5.5-year period.
It is at about 10.5 magnitude with a short tail to the north. It will be
easy for a 15cm reflector. I have been watching this comet by the 20cm
telescope since March.
