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82P/Gehrels 3

Past, Present, and Future Orbits by Kazuo Kinoshita

NEAT image of 82P exposed on 2004 January 2
Copyright © 2002 by Near Earth Asteroid Tracking (NEAT)

The above image is a stack of three 60-second exposures obtained on 2002 January 18.37, January 18.39, and January 18.41 by the Near Earth Asteroid Tracking (NEAT) program.

Discovery

A series of photographs were obtained by T. Gehrels and R. Adams (Palomar Observatory, California, USA) using the 122-cm Schmidt telescope during the end of 1975 October, as part of Gehrels' survey for unusual solar system objects. As he examined these plates during the first week of November, he found a trail on an exposure obtained on October 27.15. He described the object as nearly stellar, but slightly diffuse, with a nuclear magnitude of 17. The object was subsequently found on plates exposed with the same telescope on October 28.16 and October 30.15.

Historical Highlights

  • The first orbit was calculated by B. G. Marsden and was published on 1975 November 12. He took five positions from the period spanning October 27 to November 9 and found the comet was moving in an elliptical orbit, with a perihelion date of 1977 July 6.1 and a period of about 8.02 years. Marsden said the perihelion date and argument of perihelion were "extremely uncertain." By the end of December, Marsden published a revised orbit with a perihelion date of 1977 April 2.14 and a period of 8.28 years. During the next few months and years, calculations by Marsden, S. Nakano, and E. I. Kazimirchak-Polonskaya established the perihelion date as April 23.22–23.23 and the period as 8.11 years.
  • The comet was recovered on 1984 August 7 by J. Gibson (Palomar Observatory, California, USA). He was using the 122-cm Schmidt (the same telescope that originally discovered the comet) and gave the nuclear magnitude as 20. A confirming photograph with the same telescope on August 8 revealed a nuclear magnitude of 20-20.5. The comet was last detected on 1987 May 24.
  • Close approaches to planets: During the 20th and 21st centuries, the comet experiences two close approaches to Jupiter:
    • 0.0014 AU from Jupiter on 1970 August 15
      • decreased perihelion distance from 5.64 AU to 3.42 AU
      • decreased orbital period from 17.16 to 8.11 years
    • 0.0755 AU from Jupiter on 2063 May 21
      • decreases perihelion distance from 3.50 AU to 3.16 AU
      • decreases orbital period from 8.27 to 8.19 years

    Additional Images

    Tichy and Moravec image of 81P exposed on 1997 January 15
    Copyright © 1997 by M. Tichy and Z. Moravec (Klet' Observatory, Czech Republic)

    The image of comet 81P/Wild 2 was taken on 1997 January 15.936 UT with 0.57-m f/5.2 reflector + CCD camera SBIG ST-8 of Klet' Observatory and is 60 seconds exposure. The field of view is 16 to 10 arcminutes with north to the top and west to the right.


    G. Masi image of 81P exposed on 1997 March 3
    Copyright © 1997 by Gianluca Masi (Ceccano, Italy)

    This image of comet Wild 2 was taken by G. Masi on 1997 March 3 at 18:57 UT. It was a 12-minute exposure obtained with a 15-cm f/5 reflector and an SBIG ST-7 CCD.


    Michael Brown image of 81P exposed on 1997 April 1
    Copyright © 1997 by Michael Brown (University of Melbourne)

    Michael Brown obtained this image using the 40-inch telescope at Siding Spring Observatory on 1997 April 1. It was actually shot through clouds.


    B. Wallis image of 81P exposed on 1997 April 7
    Copyright © 1997 by Brad D. Wallis (California, USA)

    This image of comet 81P was taken on 1997 April 7.27 UT with a 0.32-m f/5.9 Ritchey telescope, an SBIG ST-7 CCD camera, and a minus-IR filter. The image was composed of eleven 5-minute exposures.


    Masayuki Suzuki image of 81P exposed on 1997 May 18
    Copyright © 1997 by Masayuki Suzuki (Japan)

    This image was taken on 1997 May 18, using a 0.20-m f/10 telescope and a CCD camera. The image is a 60-second exposure.


    D. Higgins image of 81P exposed on 2003 January 11
    Copyright © 2003 by David Higgins (Hunters Hill Observatory, Canberra, Australia)

    This image was taken on 2003 January 11.92, using a 0.25-m SCT f/5 and an SX MX516 ccd camera. The image was composed of thirty 30-second exposures. The coma was 20.6 arc seconds across, while the tail extended 22.4 arc seconds toward PA 315°. The image was originally white with black stars and the webmaster reversed this to better represent the appearance of the comet.

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