Comet C/1780 Messier

Report from the Connoissance des Temps for 1784, p. 176.

Translated from French by H. Frommert

Comet observed in 1780

This comet is the sixty-fifth for which orbital elements are known, & the eighteenth which M. Messier observed at the Observatory of the Navy, since the year 1758.

M. Messier discovered this comet with an achromatic refractor of larte aperture on October 27 at about 4:30 in the morning, below [south of] the beautiful star Beta in the tail of the Lion: It resembled then the nebula which is placed between the head and the bow of Sagittarius [M22].

From October 27 to 31, the sky didn't permit to see it again, because of a fog constantly rising; but on November 1 at 3:30 in the morning, the fog had disappeared, M. Messier observed the comet again with the same refractor; it appeared now above [north of] the same star Beta in the Lion, having a bit more light than on October 27; one couldn't yet perceive it with the naked eye.

M. Messier has continuously observed it from October 27 to November 29 in the morning, in the Lion & in the Great Bear. M. Méchain saw it again on December 3 with an achromatic refractor.

M. Lexell, astronomer of the imperial Academy of Russia, who was then at Paris, has calculated the orbit of this cometfrom observations of Messier: Here are the elements he deduced:

  Longitude of node:                    4s  4d  0'  0"
  Inclination:                             53. 56. 28.
  Longitude of perihelion of the orbit: 8s  6. 30. 14.
  Logaritm of perihelion distance:           8.9903713
  Passage of Periherlion: September 30, 1780 at 20h 16'
    22" standard time. Motion retograde.
The orbit of this comet is not resembled by any of those that are known.

Hartmut Frommert
Christine Kronberg

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