Comet Williams, also known as C/1998 P1, is a non-periodic comet that was observed between August 1998 and April 1999. It is the only comet discovered by Australian astronomer Peter F. Williams.
Observational history While observing the nova EK Trianguli Australis after many days of unfavourable weather, the comet was visually discovered by Peter Francis Williams while using an reflector telescope on the night of 10 August 1998. At the time, it was a magnitude-9.5 object within the constellation Circinus. Additional observations by Gordon J. Garradd, David A. J. Seargent, Steven Lee, and other astronomers later verified the existence of this comet on two subsequent nights after discovery, albeit at a much fainter magnitude between 13.4 and 16.0. Orbital calculations indicate the object to be a non-periodic comet with a perihelion date of 17 October 1998. By September 1998, an apparent outburst increased its brightness to 7.4.
The comet's brightness remained consistent throughout its outbound trajectory. Alan Hale reported its apparent magnitude of 9.4 in November 1998. The comet slightly brightened back to magnitude 9.0 on December 1998, and magnitude 9.2 on February 1999, respectively.
Orbit The comet has a retrograde orbit that is inclined by about 145.73° from the ecliptic. It reached perihelion at a distance of on 17 October 1998. A study of the non-gravitational effects on this comet indicate that it was dynamically new, and its apparition in 1998 were likely its first passage through the inner Solar System. Further orbital projections show that this comet may have an 80% probability that it will be ejected from the Solar System on its next few perihelion passages or apparitions.
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References
External links
C/1998 P1 at Seiichi Yoshida's website