23P/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 at the Altona Observatory on July 20, 1847, and again by Kaspar Schweizer (Moscow) on August 11, 1847. It was predicted that it would reappear between 1919 and 1922.

Discovered byTheodor Brorsen and Joel Metcalf
Discovery dateJuly 20, 1847
1847 O1, 1919 Q1, 1989 N1
Orbital characteristics A
EpochOctober 1, 1989
Aphelion33.65 AU
Perihelion0.478 AU
Semi-major axis17.07 AU
Orbital period70.52 a[1]
Last perihelionSeptember 11, 1989[1]
Next perihelionJune 8, 2059[2][3]

On August 21, 1919, the comet was recovered by Joel Hastings Metcalf (Camp Idlewild, Vermont, United States) as 8th magnitude. Additional discoveries were made by Edward Barnard (Yerkes Observatory, Wisconsin, United States) 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.


  1. ^ a b c "JPL Small-Body Database Browser: 23P/Brorsen-Metcalf". Jet Propulsion Laboratory. Archived from the original on September 18, 2019. Retrieved October 17, 2011. last obs. used 1989-09-09
  2. ^ Seiichi Yoshida (2005-11-09). "23P/Brorsen-Metcalf". Seiichi Yoshida's Comet Catalog. Retrieved February 19, 2012.
  3. ^ Horizons output. "Observer Table for Comet 23P/Brorsen-Metcalf (1989)". Retrieved February 19, 2012. (Observer Location:@sun)

External linksEdit

Numbered comets
23P/Brorsen–Metcalf Next