Copyright © 1979 by Charles T. Kowal (Palomar Observatory, California, USA)
DISCOVERY IMAGE: Charles T. Kowal obtained this photograph on 1979 January 27.11, using the 122-cm Schmidt telescope. It is a 2-hour exposure on a IIIa-J photographic plate and a Wratten 2c filter. The comet's magnitude was estimated as 17. North is up and east is left. This is a 5x enlargement from the discovery plate. (Special thanks to Charles T. Kowal for allowing me to use this image.)
Charles T. Kowal (Palomar Observatory, California, USA) discovered this comet on photographic plates exposed with the 122-cm Schmidt telescope on 1979 January 27, 28, and 29. The plates exposed for dwarf galaxies. The comet was then estimated as magnitude 17. There was some slight condensation within the diffuse coma, but no tail was visible.
B. G. Marsden (Central Bureau for Astronomical Telegrams) already suspected this comet moved in a short-period orbit upon receiving the precise positions on January 31. After T. Seki (Kochi Observatory, Japan) obtained a precise position on Febraury 1, he published a short-period orbit with an estimated period of 10.3 years. By the end of February, further precise positions from Seki enabled Marsden to revise the period to 7.05 years. The comet was last seen on March 28 and Marsden further revised the period to 6.51 years, but the short observational arc made this slightly uncertain.
Although the comet's brightness was not expected to exceed magnitude 15 during the 1997-1998 apparition, observations during 1997 November already revealed it over a magnitude brighter than expected. Observers frequently found the comet close to magnitude 13.5 throughout December, and by mid-January it had increased to about 13. The coma diameter always remained small from November through January, with estimates ranging from 0.8 to 1.6 arc minutes.
Early in December of 2003, G. W. Kronk found that a previously unpublished comet discovery made by the Reverend Leo Boethin in January of 1973 was a prediscovery observation of comet 104P. Boethin (Bangued, Philippines) found the comet with his 8-inch Newtonian reflector around 4 a.m. local time on 1973 January 12 (January 11 UT). He estimated the magnitude as 9.5 and measured the coma diameter as 7 arc minutes. He reobserved the comet the next morning and again noted the magnitude as 9.5. He said the coma was then 8 arc minutes across and exhibited a stellar nucleus. Boethin saw the comet one last time on January 13 UT, but said the brightness had faded to magnitude 13.0--near the limit of his telescope. The comet was reported to the Central Bureau for Astronomical Telegrams by letter. By the time it arrived, the moon made observations impossible and the comet was never seen after Boethin's final observation. Kronk found that comet 104P was within 2 arc minutes of Boethin's comet and was moving in the same direction, with the same rate of motion. He reported this information to the Central Bureau and noted the comet was probably fading from an outburst. B. G. Marsden found he was able to link Boethin's visual positions to those of 104P and found the perihelion date as 1972 August 4. He agreed with the scenario that the comet had undergone an outburst. The announcement was published on IAU Circular No. 8255 (2003 Dec. 11).
Kazuo Kinoshita has examined the orbital evolution of this comet for the period of 1946 to 2022. He found the orbit had undergone very little change from 1946 until an approach of 0.9827 AU from Jupiter on 1996 January 15. This encounter reduced the perihelion distance from 1.50 AU to 1.40 AU and reduced the orbital period from 6.38 years to 6.18 years. The encounter was also a sign of things to come, as, following the next perihelion date in 2004, the comet will pass 0.2819 AU from Jupiter on 2007 June 25. This will reduce the perihelion distance from 1.40 AU to 1.17 AU and the orbital period from 6.19 years to 5.90 years. Still another encounter in 2019 will further reduce the perihelion distance and orbital period.
Copyright © 1997 by Akimasa Nakamura (Kuma Kogen Astronomical Observatory, Japan)
This CCD image was taken on 1997 November 20.41, using a 0.60-m f/6 Ritchey-Chretien telescope.
Copyright © 1997 by Masayuki Suzuki (Japan)
This image was obtained on 1997 December 21 with a 20-cm f/9 telescope and a CCD camera. Exposure time was 90 seconds. The image measures 16x12 arc minutes. He estimated the magnitude as about 13.5.