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47P/Ashbrook-Jackson

Past, Present, and Future Orbits by Kazuo Kinoshita

G. Rhemann image of 47P exposed on 1993 October 10
Copyright © 1993 by Gerald Rhemann

This image was obtained on 1993 October 10.89 UT with the 171/200/257mm Schmidt camera. Exposure time was 7 minutes and the photographic emulsion was hypered Technical Pan 2415. The comet's total magnitude was then about 11.5. (The image has been cropped by the webmaster to save space and reversed to better represent the visual appearance of the comet.)

Discovery

     This comet was independently discovered by astronomers in the United States and South Africa. The first discovery was made by Yale astronomer Joseph Ashbrook. Ashbrook was visiting Lowell Observatory (Arizona, USA) to observe minor planets. While examining a photo exposed on August 26 for asteroid 1327 Namaqua, he found the comet and said it appeared diffuse, with a short tail. Twelve hours later, Cyril Jackson (Yale-Columbia Station, Johannesburg, South Africa) was experimenting with a 50-cm focus camera to test its ability to photograph fast moving minor planets. This comet was revealed on one of the plates.

Historical Highlights

  • Despite the large perihelion distance of 2.3 AU, this comet typically reaches a magnitude brighter than 12 as it is one of the intrinsically brightest short-period comets.
  • The comet's orbital period is about 7.5 years. It has been observed at every return following the 1948 discovery.
  • Investigation into the motion of this comet reveals it had been ejected into its discovery orbit in 1945, when it passed only 0.178 AU from Jupiter.
  • Apparition of 2001: K. Muraoka took positions from the years spanning 1948-1996 and predicted the comet would next return to perihelion on 2001 January 6.50.
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