Copyright © 1998 by A. Nakamura
The CCD image was taken by Akimasa Nakamura (Kuma Kogen Astronomical Observatory, Japan) on 1998 December 24.85 UT, using a 0.60-m f/6 Ritchey-Chretien telescope. Three images were superimposed to strengthen the image of the comet. Since the comet was moving, this resulted in every star appearing three times.
This comet was found by Sylvain Arend and F. Rigaux (Royal Observatory, Uccle, Belgium) on plates exposed for a routine minor planet survey on 1951 February 5 and 6. The comet was then described as about magnitude 11 and was said to be diffuse, with a central condensation. Prediscovery images were later found at two observatories. McDonald Observatory (Texas, USA) found images on plates exposed on January 8 and February 4, while Tokyo Observatory found an image on a plate exposed on January 28.
The discovery apparition was an extremely favorable one for this comet and astronomers noted a coma and tail on several occasions. But the next apparition in 1958 was somewhat different. Although an object was found very close to the predicted position, it was distinctly asteroidal in appearance. Three weeks' worth of observations revealed the "asteroid" was moving in the identical orbit as Arend-Rigaux and astronomers knew they had the correct object. No coma or tail was detected throughout this apparition. Interestingly, no coma or tail was seen during the 1963 and 1970 apparitions either. The very favorable return of 1978 did enable astronomers to again detect a faint coma and tail, confirming the cometary nature.
The comet's orbit has been extremely stable as it has not passed less than 0.9 AU from Jupiter during the last nine centuries. Long-term projections indicate significant alterations will not occur until the 24th century when the comet experiences two rather close approaches to Jupiter.
Apparition of 1998: K. Muraoka took positions from the years spanning 1951-1993 and predicted the comet would next return to perihelion on 1998 July 12.60.
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