The first(!) visual(!) amateur discovery in 2001 was achieved by Vance A. Petriew on Aug. 18 at a Star Party in Canada with a 51cm-reflector in the constellation Taurus. It was discovered by chance during a search for M1. The discoverer suspected a galaxy at first, but passing R. Huziak was convinced at first sight that it was a comet. It presented itself as a 11m bright, tailless object with a round 3' coma and a central condensation (IAUC 7686). It is suprising that the automated search projects did not find this object, for it was positioned at a convenient altitude in the morning sky. Further observations revealed this comet to be periodic with an orbital period of 5.5 years. S. Nakano indicated that the orbit is similar to the one of comet 103P/Hartley 2 (IAUC 7688). It had a close encounter with Jupiter in spring 1982 (minimal distance appx. 0.2 A.U.).
The number of observations for this moderately bright comet remained small. Besides the 11 observations by 7 members of the German comet section only 70 international observations could be taken into account for the analysis. The observations show much scatter regarding the brightness estimates, especially during the first days. The brightness evolution can be best described by the formula
m ~ 10.5m + 5×log D + 30×log r
indicating a maximum brightness of 9.6m at the end of August. Perhaps the systematically too faint brightness estimates at the beginning may indicate a rapid brightness increase shortly before discovery. The apparent coma diameter decreased from 3-3.5' at the beginning to 1.7' in mid-October. In parallel the absolute coma diameter decreased from 140.000 km to 90.000 km. The degreee of condensation remained constant throughout the apparition at DC 3-4.
Total Brightness and Coma diameter
Andreas Kammerer
