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102P/Shoemaker 1

Past, Present, and Future Orbits by Kazuo Kinoshita

AAO image of 102p exposed on 1991 September 27
Copyright © Anglo-Australian Observatory Board

In the course of the Anglo-Australian Observatory 2nd Epoch Southern Red Survey, the 1.2-m UK Schmidt Telescope at Siding Spring (Australia) accidently photographed this comet on 1991 September 27.41. The comet trailed during the exposure of the Kodak IIIaF (red) plate. This image was obtained through SkyMorph at the Goddard Space Flight Center.


     Carolyn S. and Eugene M. Shoemaker (Palomar Observatory, California, USA) discovered this comet with the 0.46-m Schmidt as part of a routine asteroid survey. An image was initially found on a photograph exposed on 1984 September 27, while a second image was subsequently found on a photograph exposed on September 28. The magnitude was estimated as 13 and the comet was condensed, with a considerable coma, but with no tail.

Historical Highlights

  • Prediscovery: R. E. McCrosky and C.-Y. Shao (Oak Ridge Observatory) found an image of the comet on a patrol plate obtained on 1984 September 1.
  • Orbit: IAU Circular 3998 (1984 October 5) contained the first orbit computed for this comet. B. G. Marsden (Central Bureau for Astronomical Telegrams) used 3 positions obtained on September 27, 28, and October 5, and computed a parabolic with a perihelion date of 1984 June 30.87. He wrote, "The comet may be a short-period one." The short-period nature was confirmed on IAU Circular 4000 (1984 October 15), when Marsden used 10 positions obtained from September 27 to October 14 and computed the perihelion date as 1984 September 15.54, the perihelion distance as 1.980 AU, and the orbital period as 7.30 years. The orbit indicated the comet passed 0.3 AU from Jupiter in 1980.
  • Visual observers saw the comet for a couple of months during 1984, beginning just a few weeks after the discovery announcement. Most observers consistently reported the magnitude as around 12 during October and November, although a few estimates reached 11 around mid-October.
  • 1991 Recovery: IAU Circular 5286 (1991 June 11) reported the recovery of this comet by A. C. Gilmore and P. M. Kilmartin (Mount John Observatory) on 1991 June 8 and 10. The comet images were described as "very weak" and the nuclear magnitude was estimated as 18. The comet's predicted position was only in error by -0.6 day.
  • The comet was not observed at its next predicted apparition of 1998-1999, when it was expected to only brighten to about magnitude 19.
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