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111P/Helin-Roman-Crockett

Past, Present, and Future Orbits by Kazuo Kinoshita

Discovery

     On 1989 January 5 it was announced that Eleanor Helin had discovered a comet on photographic plates obtained by Ron Helin, Brian Roman, and Randy Crockett with the 0.46-m Schmidt telescope at Palomar Observatory on January 2.43 and 3.43. The magnitude was estimated as 15.5 on the latter date, and the comet was described as "condensed with a coma and small tail to the northwest."

Historical Highlights

  • Following the acquisition of images obtained from the discovery through January 6, Brian G. Marsden (Central Bureau for Astronomical Telegrams) computed the first orbit which was published on the 7th, and which he considered "extremely uncertain." It was parabolic and indicated a perihelion date of 1988 June 24 and a perihelion distance of 2.2 AU. He added, "It is at least equally likely that the object is a distant short-period comet with a very low [eccentricity]." The short-period nature was confirmed a few days later, after observations had been made through the 11th. Marsden determined the perihelion date as 1988 June 30, the perihelion distance as 3.48 AU, and the orbital period as 8.20 years. The large perihelion distance and short arc still made it likely that the orbit was somewhat in error. By the end of March, with over two months of observations available, the orbit was revised again. The resulting perihelion date was 1988 September 9.9, the perihelion distance was 3.472 AU, and the orbital period was 8.12 years.
  • Several observers estimated the brightness as near 15 around mid-January and this became the maximum brightness for this apparition. Although the comet comet was fading slowly, observations nevertheless ceased on May 8.
  • The comet was recovered on 1993 June 25.42 and remained under observation until 1998 February 28.50. The perihelion date was 1996 October 31.78. The maximum total magnitude was slightly brighter than 19 during early 1997.
  • The comet will next pass perihelion on 2004 December 27. It was recovered on 2001 July 27.28.
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