83D/Russell

83D/Russell, once designated 83P/Russell, is a periodic comet that has been classified as lost. It orbits the Sun roughly every 7.5 years. The comet has not been observed in years. The comet was first spotted on 16 June 1979 by Kenneth S. Russell at the UK Schmidt Telescope in Australia. He described it as faint and diffuse, with a very low brightness of magnitude 18. Early orbit calculations placed its perihelion on 27 May 1979 and gave it an orbital period of 6.13 years. The predicted return in 1985 was observed by J. Gibson using the 1.5-meter reflector at Palomar Observatory in California, who estimated the nucleus at a very faint magnitude 19.5. On 9 August 1988, the comet passed within 0.05 AU (about 7.5 million km) of Jupiter. This gravitational encounter lifted its perihelion distance from 1.6 AU to 2.1 AU, making the comet fainter, less active, and harder to recover. Its predicted return in 1991 was missed due to unfavourable conditions, and it was missed again in 1998. Although conditions were favourable in 2006, the comet was not relocated, leading to its current classification as lost. In mid-March 2021, the comet was expected to come to opposition in the constellation Crater at around apparent magnitude 20.9. On its post-1988 orbit, the comet probably does not get brighter than about magnitude 21. The comet might reach perihelion in late November 2028, but the uncertainty in its position is a few million kilometres. In early January 2028, it may come to opposition in Monoceros at around magnitude 23.7, and in mid-June 2029, it may come to opposition in Ophiuchus at around magnitude 22.2.