D/1770 L1 ( Lexell )

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Updated on November 27, 2005

Profile In 1770, it passed extremely close by the earth down to 0.0146 A.U. on July 1, and reached to -2 mag. The light curve during three and a half months between June and October yields the absolute magnitude of H10 = 7.5 mag. The condition in 1776 was worst, not observable at all. Kazuo Kinoshita's calculation revealed that it passed extremely close by Jupiter down to 0.0016 A.U., then the perihelion distance increased extremely from 0.7 A.U. up to 5.2 A.U. It was observed with a heliocentric distance up to 1.2 A.U. in 1770. So the brightness at the distance of 5.2 A.U. is completely uncertain. It is about 18 mag in calculation, but it may be fainter than 20 mag. Kazuo Kinoshita's calculation reveals that it must have returned around 1984, but it was not observed. It is natural to be missed at that time because the comet must have been fainter than 18 mag. It may be recovered in the next return around 2184. Returns and Appearances Discovered Appeared Not observed Appeared before discovery Not observed before discovery Returns in the future 2184 Nov. 29 1984 Jan. 15 1776 Mar. 22 D/1770 L1 1770 Aug. 14

The perihelion dates in the past appearances are printed on Catalog of Cometary Orbits 1996. The perihelion dates since 1776 are calculated by Kazuo Kinoshita (http://www9.ocn.ne.jp/~comet/pcmt/h70l1.htm). Information on the discovery and historical highlights are available at General Comet Info (Gary W. Kronk). Orbital elements in the past and future are calculated by Kazuo Kinoshita (http://www9.ocn.ne.jp/~comet/pcmt/h70l1.htm).