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Past, Present, and Future Orbits by Kazuo Kinoshita

NEAT image of 147P exposed on 2002 February 4
Copyright © 2002 by Near Earth Asteroid Tracking (NEAT)

This image is a combination of three images obtained by the Near Earth Asteroid Tracking (NEAT) program on 2002 February 4.47, February 4.48, and February 4.49. Each image was exposed for about one minute.


     Yoshio Kushida and Osamu Muramatsu (Yatsugatake South Base Observatory, Japan) photographically discovered this comet on 1993 December 8.65. They were using the 25-cm f/3.4 reflector. The comet was described as diffuse, about 1-2 arc minutes across, and centrally condensed. The magnitude was estimated as 16.5. They obtained a confirmation photograph on December 9.54, which also indicated a magnitude of 16.5.

Historical Highlights

  • The first orbit was calculated by S. Nakano. Using positions spanning the period of December 8 to 12, he determined a parabolic orbit with a perihelion date of 1994 November 26.16. The possibility that this might be a short-period comet was also expressed. The short-period nature was confirmed by Nakano on December 16 when he took positions covering the period of December 8-15 and calculated a perihelion date of 1993 November 4.46 and a period of 6.92 years. During the next few weeks, the perihelion date was eventually determined as December 10.25, while the period was 7.40 years.
  • The comet attained a maximum brightness of magnitude 15 during 1993 December. It was last detected by J. V. Scotti (Spacewatch) on 1995 June 23.19, when images were obtained using the 91-cm reflector. The total magnitude was then given as 21.2, while the nuclear magnitude was given as 22.6.
  • Apparition of 2001: During 1998, Nakano took 204 positions spanning the comet's entire 1993-1994 apparition, applied perturbations by Mercury to Neptune, as well as the minor planets Ceres, Pallas, and Vesta, and predicted the comet would next arrive at perihelion on 2001 April 29.55. The comet was recovered on 2000 October 3.72, when T. Oribe (Saji Observatory) obtained CCD images with the 103-cm reflector. Oribe said the comet's magnitude was 20.2 and the coma was 10 arc seconds across. His precise position indicated Nakano's prediction was only 0.04 day late. The comet only became slightly brighter than magnitude 20 when brightest. It was last detected on 2002 March 20.17, when it was imaged using the Spacewatch 91-cm reflector. The magnitude was then given as 21.2.
  • An international team led by P. L. Lamy (France) used the Hubble Space Telescope to observe several comets during the period of July 2000 to June 2001, with the purpose being to characterize their nuclei. For 147P, they determined the nucleus was 0.26 km in diameter.
  • Apparition of 2008: The comet was recovered on 2008 December 21.30, using the Spacewatch 91-cm reflector. The magnitude was given as 19.8. The comet attained a maximum brightness of about 19 near the end of December 2008 and beginning of January 2009.The comet was last observed by Hasubick on 2009 February 28.03. The magnitude was then estimated as 20.
  • A paper was published by K. Ohtsuka, T. Ito, M. Yoshikawa, D. J. Asher, and H. Arakida in the journal Astronomy and Astrophysics during October 2008. They showed how a careful examination of the past orbit of this comet indicated it was a temporary moon of Jupiter from about 1949 May 14 until 1961 July 15. The results were also presented at a German conference on planetary science during September 2009.
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