Copyright © 1999 by M. Jäger
This image was taken by Michael Jäger on 1999 January 6.81. He used a 25.4-cm, Schmidt camera. Exposure time was 10 minutes and the photographic emulsion was hypered TP6415. (Thanks to Gerald Rhemann for permission to use this image.)
Discovery
Robert G. Harrington and George O. Abell (Palomar Observatory, California, USA) discovered this comet on a plate taken on 1955 March 22.30, with the 122-cm Schmidt camera during the National Geographic Society-Palomar Sky Survey. The comet was estimated as magnitude 17, and was described as diffuse, with a central condensation, and a tail less than 1° long. The comet was confirmed on photographic plates exposed on March 27.38 and March 30.36. On the latter date, the nucleus was magnitude 19.0 and was surrounded by a faint coma.
Historical Highlights
Leland E. Cunningham (Leuschner Observatory, Berkeley, California, USA) computed the first orbit which was published on 1955 April 25. It used the three initial Palomar positions and indicated the comet was moving in an elliptical orbit. The perihelion date was given as 1954 December 18, while the orbital period was 7.01 years.
Because of the comet's faintness, it was not followed for a long time during its discvoery apparition. George van Biesbroeck photographed it twice with the 82-inch reflector at McDonald Observatory during the latter half of April. He estimated the magnitude as 19.5 on each occasion, and said the coma was 5 arc seconds across. The comet was last seen on May 18.23 and May 18.32, when Elizabeth Roemer (Lick Observatory) obtained exposures of 120- and 100-minute durations, respectively, with the 36-inch f/5.8 Crossley reflector. She determined the magnitude as 19.2, and said the comet appeared slightly diffuse.
The comet has been seen at every apparition, beginning with its first recovery on 1962 January 26 by Alan McClure. It tends to remain a faint object. Further appearances came in 1962, 1969, 1976, 1983, and 1991.
K. Muraoka took positions from the years 1955-1990 and predicted the comet would next pass perihelion on 1999 January 27.87. Although this was predicted to be a typical apparition, the comet had other plans. The comet was recovered on 1998 July 21 by A. Maury (l'Observatoire de la Côte d'Azur, France). Using the 0.9-m Schmidt reflector and a CCD, he was expecting a comet faintly shining at a magnitude of 21 or 22, but instead detected a comet of magnitude 12.2. This unusual brightness was confirmed the next night by several observers who estimated the visual magnitude as 10.9 to 11.8. The coma was between 1 and 3 arc minutes across. The comet's enhanced brightness continued for many months and observers were reporting total magnitudes of about 11 around the time the comet passed perihelion on 1999 January 27. The coma diameter was then about 3 arc minutes across. The comet slowly faded during February and as March began most visual observers were estimating the magnitude as between 11.5 and 12. The coma was then slightly larger than 2 arc minutes. For most of first half of 1999, the comet continued to maintain its enhanced brightness for visual observers, although it finally dropped below magnitude 12 by the end of March, while the coma diameter had declined to 2 arc minutes. Observations continued throughout April and May. By the middle of the latter month, when previous brightness prediction formulas indicated the comet would be faintly shining at magnitude 19.5, most visual observers were still reporting the comet was between 12.7 and 13.0.
Additional Images
Copyright © 1998 by H. Mikuz
This image was taken by Herman Mikuz on 1998 July 24. He used a 36-cm, f/6.8 S-C telescope, V-filter and CCD. Exposure time was 3 minutes. The comet was then undergoing an outburst in brightness and had never been seen at this brightness during previous apparitions.
Copyright © 1999 by Yuichi Chimura
This image was obtained by Yuichi Chimura of Japan on 1998 December 26. It was made using a 0.13-m f/6.1 Takahashi MT-130 and an SBIG ST-7.
Copyright © 1999 by Konrad Horn
This image is a composite of several images obtained by Konrad Horn of Germany during the period of 1999 January 15 to 23, just prior to passing perihelion. North is to the right and the comet's southward motion is plainly illustrated.
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