Copyright © 2002 by Near Earth Asteroid Tracking (NEAT)
REDISCOVERY IMAGE: The Near Earth Asteroid Tracking (NEAT) program at Palomar Observatory (California, USA) obtained three images of a comet on 2002 October 11, which proved to be the lost periodic comet 54P/de Vico-Swift. This image is a combination of three images shot with the 48-inch Oschin telescope and a CCD camera on October 11.22, October 11.29, and October 11.36. Each image was exposed for about 2.5 minutes.
Francesco de Vico (Rome, Italy) discovered this telescopic comet during a routine search for comets on 1844 August 23.09. It was then situated in Aquarius and was 0.20 AU from Earth and 1.19 AU from the sun. He confirmed his find on August 24.09. Independent discoveries were made by Melhop (Hamburg, Germany) on September 6 and by Hamilton L. Smith (Cleveland, Ohio, USA) on September 10.
Edward Swift (Echo Mountain, California, USA) discovered this comet on 1894 November 21.18. It was then situated in Aquarius and was described as very faint, with a small nucleus and a faint, short tail. Even before an orbit was published, A. Berberich suggested the comet might be the same as de Vico's comet on the basis of the comet's location and direction of motion.
K. Lawrence, S. Pravdo, and E. Helin (Jet Propulsion Laboratory, California, USA) announced the discovery of a comet on images obtained on 2002 October 11.22 by the Near Earth Asteroid Tracking (NEAT) program at Palomar Observatory (California, USA). They gave the magnitude as 19.3 and noted a nuclear condensation about 4 arc seconds across and a tail about 20 arc seconds long. Several prediscovery images from October 4 and 9 were then found by members of the LINEAR program (New Mexico). B. G. Marsden (Central Bureau for Astronomical Telegrams) took the 22 positions spanning October 4 to 12 and calculated an elliptical orbit with a perihelion date of 2002 July 25.54 and a period of 7.53 years. The comet was designated comet P/2002 T4. K. Muraoka (Kochi, Japan) very quickly identified this comet as a return of comet 54P/de Vico-Swift. This was confirmed by Marsden, who then published an orbit with a perihelion date of July 30.94 and a period of 7.31 years.
The 1844 apparition was exceptional for this comet as it passed only 0.19 AU from Earth on September 1. Laugier and Felix Victor Mauvais published a parabolic orbit on September 9 and noted that a similarity existed between the orbit of this comet and those seen in 1585, 1678, 1743, and 1770. Further investigations by these astronomers produced the suggestion that the same comet was seen in each year and that its orbital period was 9.2 years. By adding another comet, comet Blanpain of 1819, into their investigation, they suggested a period between 4.6 and 4.9 years. As it turned out, de Vico's comet was not seen during those previous years. Hervé Faye (Paris) computed the first elliptical orbit on September 16. He determined the perihelion date as September 3, the perihelion distance as 1.18 AU, and the orbital period as 5.13 years. The comet was widely observed during September and October. The final observation was obtained on December 31. Faye computed a more definitive orbit on December 9 which indicated the orbital period was 5.46 years.
The comet was not recovered at subsequent returns. That of 1850 was not particularly favorable, but the 1855 return was very favorable because of the comet's approach to within 0.58 AU from Earth. Numerous searches were conducted during the later year, but cloudy weather hampered the large European observatories during the best observing times. Interestingly, Goldschmidt reported an object on May 17 which was only 1.5 degrees from the predicted position. The object was not seen after that date and later calculations revealed it could not have been de Vico's comet. After further unsuccessful searches in 1860 and 1866, the comet was considered lost.
After the 1894 discovery the comet steadily faded. When last seen on 1895 January 30 the magnitude had declined to 14. The comet's motion was investigated by various astronomers. Schulhof noted the comet had passed 0.60 AU from Jupiter in 1885 which accounted for the differences between the 1894 orbit and that of 1844.
Following the 1894 apparition, F. H. Seares computed a definitive orbit for comet Swift and then set out to compute its future path. He noted a close approach to Jupiter (0.44 AU) in 1897 that would act to increase the orbital period from 5.85 to 6.40 years. The 1901 return was very unfavorable and the comet was not found. The 1907 return was more favorable and numerous searches were made, the highlight of which was a 3.5-hour photographic exposure by A. Kopff, but no trace of the comet was found. The comet was again lost.
Interestingly, the likelihood of de Vico's comet of 1844 and Swift's comet of 1894 being identical had never been absolutely determined until 1965. Using a computer, B. G. Marsden set out in 1963 to investigate this problem. He linked the 1844 and 1894 comets with remarkable precision and then proceeded to determine the next favorable apparition. He found a return in 1965 would be very favorable and requested Joachim Schubart to undertake an independent calculation. Schubart confirmed the correctness of Marsden's calculations, but with an 11-day difference in the perihelion date. Arnold Klemola (Yale-Columbia Southern Observatory, Argentina) recovered the comet on 1965 June 30 at a magnitude of 17. The comet was on a line connecting Marsden and Schubart's predictions, though slightly closer to the latter. The comet became as bright as 15 in late September. It was last seen on October 15 because of its entrance into twilight.
The comet passed 0.16 AU from Jupiter on 1968 October 18, which increased both the perihelion distance and orbital period. Subsequently, the most favorable apparition was not expected to be brighter than magnitude 18. Despite published predictions for the comet's return in 1973, 1980, 1987, and 1995 the comet was not found and was considered lost.
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