99P/Kowal 1

 

99P/Kowal 1 was discovered by Charles Kowal on April 24^th 1977 on plates taken with the 48-inch (1.2-m) Oschin Schmidt at Mount Palomar. It was rapidly realized to be a somewhat unusual object because, despite being around magnitude 16, it was already nearly 4 months past perihelion and at nearly 5AU from the Sun. In other words, it was clearly an unusually active object. Perihelion was at 4.65AU and the period 15.0 years, although the eccentricity of the orbit (e=0.235) was unusually low.

 

The comet will make its second return to perihelion in 2007. The perihelion distance has been increasing recently due to repeated moderately close encounters to Jupiter (0.3-0.6AU) in the 20^th and 21^st centuries. From 4.41AU in 1900, it decreased to a minimum of 4.30AU in 1946 and will reach its maximum of 4.96AU in 2051 before decreasing slightly again. At the same time, the period has reached a minimum of 12.7 years and will reach a maximum of 18.6 years.

 

To date there are only observations on four nights early in 2005, all by MPC 213 and made around two years before perihelion, with the comet at a heliocentric distance between 5.4 and 5.3AU.

 

At this distance the activity has been very low, with values of Afrho of approximately 7-cm.