Shoemaker-Levy 9
Copyright © 1994 by H. A. Weaver and T. E. Smith (Space Telescope Science Institute), and NASA
A NASA Hubble Space Telescope (HST) image of comet P/Shoemaker-Levy 9, taken on May 17, 1994, with the Wide Field Planetary Camera-2 (WFPC-2) in wide field mode. This required 6 WFPC exposures spaced along the comet train to include all the nuclei. The image was taken in red light.
Discovery
Carolyn S. and Eugene M. Shoemaker and David H. Levy (Palomar Observatory in California) examined a pair of photographs exposed on 1993 March 24 as part of a routine asteroid survey. Although the team had already discovered numerous comets during the previous few years, these photographs held a most unusual object. Each plate revealed a comet which resembled a dense linear bar, with a faint, wispy tail. At a later date, they said their initial reaction was that the comet appeared "squashed." The comet was reported to the appropriate authorities, and was named Shoemaker-Levy. A more formal name of periodic comet Shoemaker-Levy 9 was later given to the comet when astronomers realized it completed one orbit around the sun every 17 years and was therefore classed as a short period comet. This was the ninth short-period comet discovered together by the Shoemakers and Levy. While the comet's initial appearance was certainly something new and unusual, the comet's location was also of interest. Brian G. Marsden's announcement of the comet on IAU Circular 5725 included his remark that "The comet is located some 4 degrees from Jupiter, and the motion suggests that it may be near Jupiter's distance." As orbits were computed it was soon realised that the comet was actually in orbit around Jupiter. An independent discovery was reported by O. Naranjo (Merida), who found the comet on a photograph exposed on March 26.2.
In the days following the comet's discovery, additional images of the comet were found on earlier plates taken elsewhere. K. Endate (Kitami) found an image on a photograph exposed on March 15.6. S. Otomo (Otomo Observatory) photographed it on March 17.6. The team of E. Helin, K. Lawrence, and C. Brewer (Palomar Observatory) found images exposed on March 19.4.
Historical Highlights
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January 8.85: The total magnitude was estimated as 15.1 and the coma length was 2.8 arc minutes. He said the fragments were oriented on a line extending from PA 64° to PA 244°. Nuclear magnitude estimates: G=18.8, H=19.1, K=18.8, L=19.0, Q=18.7, R=19.3, S=19.6.
April 13.73: The total magnitude was estimated as 15.2 and the coma length was 5.2 arc minutes. He said the fragments were oriented on a line extending from PA 63° to PA 243°. Nuclear magnitude estimates: G=18.7, H=19.0, K=18.8, L=19.1, Q=18.4, R=19.6, S=19.5.
June 1.55: The total magnitude was estimated as 15.0 and the coma length was 6.8 arc minutes<. He said the fragments were oriented on a line extending from PA 64° to PA 244°. Nuclear magnitude estimates: F=19.6, G=18.7, H=19.0, K=18.9, Q=18.3, R=19.1, S=18.7, W=19.7.
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--The Kuiper Airborne Observatory detected water within the "splash phase" of Fragments G and K.
--Near-infrared Spectroscopy was obtained at the United Kingdom Infrared Telescope at Mauna Kea, Hawaii. In a paper by T. Y. Brooke, G. S. Orton, D. Crisp, A. J. Friedson, and G. Bjoraker it was revealed that carbon monoxide was detected at the site of the L event about four hours after impact.
--Detection of sodium, iron, magnesium, calcium, and manganese was made during the impact of fragment L, while sodium D was found during the impact of Q1.
--Observations of the impacts of A, H, and Q were made at the Serra La Nave Station of the Catalina Astrophysical Observatory by C. Blanco, G. Leto, and D. Riccioli. Photometric monitoring of Europa and Io revealed slight brightenings at the time of the A and Q events.