Copyright © 2005 by Michael Jäger and Gerald Rhemann (Austria)
This CCD image was obtained on 2005 October 9.89, using a 30-cm Deltagraph and a SXVH-9 CCD camera. Five 150-second exposures were stacked to create this image.
Nikolaj Stepanovich Chernykh (Crimean Astrophysical Observatory) discovered this comet with a 0.4-m astrograph, during the course of a regular minor planet program, on 1977 August 19.02. It was then located within Pisces. He estimated the magnitude as 14, and described the comet as diffuse, with a condensation. Chernykh confirmed his find on August 20.01.
An elliptical orbit was first computed for this comet on 1977 September 7. M. P. Candy reported how the comet would pass perihelion on 1978 January 2.9, with the perihelion distance being 2.640 AU. The orbital period was given as 13.0 years. Independent orbits published by Candy and B. G. Marsden on September 23 moved the perihelion date back to 1978 February 14, while the perihelion distance dropped to 2.57 AU. The orbital period was increased to 15.8 years. The comet steadily brightened during the following months and reached magnitude 12.5 during late October, before the brightness declined. This decline was a result of the comet's increasing distance from Earth, having passed closest to our planet on October 4 (1.81 AU). Thus, despite a decreasing distance from the sun, the comet dropped to 13 by late November and 14 by the end of December. The comet was lost in the sun's glare early in 1978, but it was seen for the final time on 1978 December 3, when it was photographed at Harvard College Observatory's Agassiz station. Revised orbital computations revealed the orbital period was 15.93 years.
S. Nakano published a prediction during 1987 which indicated this comet would return to perihelion on 1992 January 27.8. J. V. Scotti and D. Rabinowitz (Lunar and Planetary Laboratory) recovered the comet on Spacewatch images exposed on 1991 June 8.41. It was described as 8 arc seconds across, with a faint tail extending more than 8 arc seconds westward. The nuclear magnitude was given as 20.3. The measured positions indicated Nakano's prediction was 2.4 days too late. Numerous amateur astronomers serached for the comet, but most failed. The only apparent observations were obtained during August, with visual estimates ranging from 12 to 14, depending on the observer. The predicted maximum magnitude was 11.6.
The highlight of the 1992 apparition was the splitting of the comet. J. Luu and D. Jewitt photographed the comet on September 15 and 16 with the 2.4-m telescope of the Michigan-Dartmouth-MIT Observatory on Mauna Kea and found a secondary nucleus situated about 1 arc minute eastward of the primary nucleus. The brightnesses of the nuclei were given as 16.1 and 19.1 for the primary and secondary, respectively. Examinations of existing photographs revealed images as early as September 7. Meanwhile, several observatories began tracking the continued separation of the primary and secondary nuclei. By late November Z. Sekanina (Jet Propulsion Laboratory) had concluded that the comet had split on 1991 April 14.7±4.1.