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36P/Whipple

Past, Present, and Future Orbits by Kazuo Kinoshita

NEAT image of 36P exposed on 2002 September 13
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 using the 48-inch Oschin telescope and a CCD camera on 2002 September 13.13, September 13.15, and September 13.17. Each image was exposed for about 2.5 minutes.

Discovery

     Fred L. Whipple (Harvard College Observatory, Massachusetts, USA) discovered this comet on the edge of a photograph exposed with the 115-cm Metcalf telescope on 1933 October 15.27. The magnitude was estimated as 13, while a tail was 3 arc minutes long. He confirmed the comet on October 21.12.
     A prediscovery apparition was identified in 1987 by S. Nakano. During 1925 September, G. Shajn (Simeis) reported the discovery observations of several minor planets. One of these was designated 1925 QD and it was first photographed on August 21.01. The only additional photograph was obtained on August 24.96. The brightness was determined as 13.0 on both dates. Nakano did an extensive search through the minor planet database at the Minor Planet Center in Cambridge, Massachusetts. During this search he found that minor planet 1925 QD was in the exact positions expected for 36P/Whipple on those dates, so that observations of this comet existed prior to its discovery in 1933.

Historical Highlights

  • The first published orbits were actually elliptical and used positions from October 15, 21, and 22. Whipple and Leland E. Cunningham determined a perihelion date of 1933 July 8.43 and an orbital period of 8.23 years, while Allan Maxwell determined a perihelion date of July 2.99 and an orbital period of 8.53 years. Whipple and Cunningham revised the orbit during the early days of November and determined the perihelion date as August 2.59 and the orbital period as 7.49 years. They added that the comet had apparently passed about 0.3 AU from Jupiter in May of 1922. Maxwell ultimately determined an orbit representing the positions from the period 1933 October 15 and 1934 March 5.
  • Apparition of 1941: Predictions for the comet's next return were independently provided by D. H. Sadler and F. M. McBain, and H. Q. Rasmusen. Sadler and McBain determined the perihelion date as 1941 January 22.69, while Rasmusen determined it as January 13.34. Cunningham recovered the comet on 1940 September 1 and estimated the magnitude as 15. His position indicated the prediction of Sadler and McBain was only 0.23 day late. The comet attained a maximum magnitude of 14 during this apparition and was followed until 1941 November 22.
  • Apparition of 1948: The Reverend Cameron Dinwoodie took the orbit predicted for the 1940 apparition by Sadler and McBain, corrected the perihelion date by -0.23 day, and advanced it forward. The result was a predicted perihelion date of 1948 June 25.85. The comet was recovered by H. M. Jeffers (Lick Observatory, California, USA), while using the 36-inch f/5.8 Crossley reflector, on 1947 June 21.40. Jeffers determined the magnitude as 18.4 and said the comet appeared nearly stellar. He confirmed it on June 21.45. The prediction by Dinwoodie needed corrected by -0.076 day. The comet attained a maximum magnitude of 14 during September and October of 1948.
  • Apparition of 1955: Dinwoodie took his own predicted orbit for the 1948 apparition, applied corrections based on six positions obtained at Lick Observatory, and applied perturbations by Jupiter and Saturn. He predicted the comet would next arrive at perihelion on 1955 November 29.89. Elizabeth Roemer (Lick Observatory, California, USA) recovered this comet on 1955 May 25.46. She estimated the magnitude as 18, and described the comet as "not quite stellar." Roemer confirmed the recovery on May 26.46. The comet attained a maximum magnitude of 13 during October.
  • Close approaches to planets: The comet experienced three close approaches to Jupiter during the 20th century and will make one close approach to Jupiter during the 21st century. (From the orbital work of Kazuo Kinoshita)
    • 0.89 AU from Jupiter on 1916 June 25
      • increased perihelion distance from 3.92 AU to 4.23 AU
      • increased orbital period from 9.99 to 11.01 years
    • 0.25 AU from Jupiter on 1922 June 20
      • decreased perihelion distance from 4.23 AU to 2.48 AU
      • decreased orbital period from 11.01 to 7.46 years
    • 0.60 AU from Jupiter on 1981 July 12
      • increased perihelion distance from 2.47 AU to 3.08 AU
      • increased orbital period from 7.44 to 8.49 years
    • 0.68 AU from Jupiter on 2040 October 16
      • increased perihelion distance from 3.02 AU to 3.79 AU
      • increased orbital period from 8.39 to 9.83 years

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