Copyright © 1995 by Herman Mikuz (Crni Vrh Observatory, Slovenia)
This image of comet d'Arrest was obtained on 1995 June 30 UT with the 36-cm, f/6.8 Schmidt-Cassegrain telescope, V-filter and Wright CCD. The exposure time was 5 minutes. The frame field of view is 11.0 arcmin by 11.0 arcmin. (The image was converted to black and white to save space.)
The comet was discovered in Pisces by Heinrich Ludwig d'Arrest (Leipzig, Germany) on 1851 June 28. It was described as very faint. The comet was not found on the next night because the sky was too hazy, but on June 30, d'Arrest described it as large and faint.
The 1950 return was unusual because the comet was not expected to exceed a magnitude of 12.5 (the maximum brightness of the more favorable 1943 appearance). However, about three weeks after passing closest to the sun, the comet experienced an outburst which took it to magnitude 10.5.
The comet's brightest appearance to date came in 1976. A close approach to Jupiter in 1968 (0.42 AU) had decreased the perihelion distance to 1.17 AU. During the 1976 return the comet was closest to Earth on the same day it passed closest to the Sun. The result was that the comet passed only 0.15 AU from Earth on August 13. It reached a maximum brightness of magnitude 4.9 and exhibited a tail one degree long.
In 1991, A. Carusi and G. B. Valsecchi (Rome) and L. Kresak and M. Kresakova (Bratislava) independently suggested this comet was the same as a comet observed by La Hire in 1678. Independent orbits were computed by Carusi and Sitarski which confirmed the link.
During 1995, the comet passed 0.3996 AU from Earth on August 9. During the latter days of August the maximum brightness reached a magnitude of about 7.5. The comet was still magnitude 11 in early November.
The comet will next pass perihelion on 2008 August 14. It will pass closest to Earth (0.35 AU) a few days earlier on August 9.
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