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173P/Mueller 5

Past, Present, and Future Orbits by Kazuo Kinoshita

Prediscovery image of 173P exposed on 1992 September 25 during the second Palomar Sky Survey
Copyright © 1993-2000 by the California Institute of Technology

In the course of the Second Palomar Observatory Sky Survey, the 122-cm Oschin Schmidt Telescope at Palomar Observatory (California, USA) accidently photographed this comet on 1992 September 25.49. The arrow points to the diffuse image of the comet. The trail was originally found by Maik Meyer (Germany) while searching for prediscovery images of comets. This image was obtained through SkyMorph at the Goddard Space Flight Center.


     J. Mueller (Palomar Observatory, California, USA) discovered this comet on a photographic plate exposed on 1993 November 20.42, using the 122-cm Oschin Schmidt Telescope in the course of the second Palomar Sky Survey. The comet appeared as a short, diffuse trail of magnitude 17.5–18. Mueller said the comet was diffuse, with a "pronounced tail" extending about 80" in PA 270 degrees. J. D. Mendenhall and Mueller confirmed the discovery on a second photographic plate exposed using the same telescope on November 21.36. An independent confirmation was made by D. D. Balam and J. B. Tatum (Dominion Astrophysical Observatory, Victoria, British Columbia, Canada). They obtained four images of the comet from November 23.40 to November 23.42, using the 182-cm reflector and a CCD camera. In 2008, M. Meyer found a prediscovery image of this comet on a plate exposed during the second Palomar Sky Survey on 1992 September 25.49. The magnitude was estimated as 17.9.

Historical Highlights

  • The first orbit was published by B. G. Marsden on 1993 November 26. Using 11 positions from the period of November 20-25, he calculated a parabolic orbit with a perihelion date of 1994 December 29.90. He noted, "It is not improbable that the comet is of short period." Marsden revised his orbit on December 11 and confirmed the short-period orbit. Using 15 positions from the period of November 20 to December 10, he gave the perihelion date as 1995 February 8.15 and the period as 14.39 years. The orbit ultimately proved to have a perihelion date of 1994 September 12.10 and a period of 13.78 years.
  • The comet was apparently at its brightest during early January of 1994, when T. Seki (Geisei, Japan) acquired images which revealed the comet at magnitude 16.5-16.8. The comet was last detected on 1995 February 1.52, when astronomers at Kitt Peak National Observatory (Arizona, USA) acquired a CCD image using the Spacewatch telescope. They noted a nuclear magnitude of 21.6.
  • Apparition of 2008: The comet was recovered on three images acquired with the 1.5-m reflector by E. J. Christensen (Mt. Lemmon Survey, Arizona, USA) during 2005 October 7.44-7.45. The magnitude was given as 18.0, the condensed coma was 8" across, and there was a curved tail extending 20" in PA 250-280 degrees. The comet peaked at a brightness of 16-17 at the beginning of 2007.
  • cometography.com