23P/Brorsen–Metcalf

23P/Brorsen–Metcalf
Discovery
Discovered by	Theodor Brorsen and Joel Metcalf
Discovery date	July 20, 1847
Alternative; designations	1847 O1, 1919 Q1, 1989 N1
Orbital characteristics A
Epoch	October 1, 1989
Aphelion	33.65 AU
Perihelion	0.478 AU
Semi-major axis	17.07 AU
Eccentricity	0.972
Orbital period	70.52 a
Inclination	19.33°
Last perihelion	September 11, 1989
Next perihelion	June 8, 2059

Comet Brorsen–Metcalf is a periodic comet with an orbital period of 70 years. It fits the classical definition of a Halley-type comet with (20 years < period < 200 years).^[1] It was first discovered by Theodor Brorsen (Altona, Germany) on July 20, 1847, and again by Kaspar Schweizer (Moscow) on August 11, 1847, the prediction was made it would return between 1919 and 1922.

On August 21, 1919, the comet was recovered by Joel Hastings Metcalf (Camp Idlewild, Vermont, USA) as 8th magnitude. Additional discoveries were made by Edward Barnard (Yerkes Observatory, Wisconsin, USA) on August 22, Michel Giacobini (Paris, France), Ostrovlev (Theodosia, Crimea) and Selavanov (Saint Petersburg). By the end of September 1919 it was confirmed as being the same as Brorsen's comet.

References

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