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217P/LINEAR

Past, Present, and Future Orbits by Kazuo Kinoshita

Ernesto Guido, Giovanni Sostero, and Paul Camilleri image of 217P exposed on 2009 March 22
Copyright © 2009 by E. Guido, G. Sostero, and P. Camilleri (Remanzacco Observatory, Italy)

Discovery

     M. Blythe reported the discovery of a comet on four images obtained with the 1.0-m reflector of the Lincoln Near Earth Asteroid Research (LINEAR) program (New Mexico, USA) on 2001 July 11. The earliest of these images was obtained on July 11.22, while the latest was obtained on July 11.25. The magnitude was variously given as 16.7 to 17.7 during this period. It was quickly realized that the comet had already been detected by LINEAR on June 21, June 24, and July 10. For the first June date, the nuclear magnitude was given as 17.6-17.9.

Historical Highlights

  • The first orbit was published by Brian G. Marsden (Central Bureau for Astronomical Telegrams) on 2001 July 12. Using 38 positions obtained from 2001 June 21 to July 12, this revealed the comet was moving in a short-period orbit with a perihelion date of 2001 November 30.47 and a period of 7.50 years. A revision by Marsden on July 23 used 71 positions from the period spanning June 21 to July 22. It determined the perihelion date as November 30.16 and the period as 7.94 years. Following the comet's recovery in 2009, an new orbit for the 2001 apparition revealed a perihelion date of November 30.13 and a period of 7.91 years.
  • The comet reached a maximum brightness of about 12 from November 2001 through January 2002. The comet was last detected on April 6, 2002, at Buchloe Observatory (Germany).
  • Apparition of 2009: This comet was recovered by Ernesto Guido, Giovanni Sostero, and Paul Camilleri (Remanzacco Observatory, Italy) using remote-controlled telescopes in New Mexico (USA) and Australia on 2009 March 17, 18, and 20. They described the comet as "a pale glow, magnitude about 18, nearly 15 arcsec in diameter." They made the following comment, "The recovered comet was very close to the ephemeris positions, however its detection has been a little problematic, because it was rather low in the morning sky just before twilight, located in a rich star field in [Sagittarius]. We took several nights of observations to locate it, fighting with clouds and moonlight interference." The comet is expected to become slightly brighter than magnitude 11 during October and November of 2009.
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