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A. Nakamura image of 188P exposed on 1998 October 21
Copyright © 1998 by Akimasa Nakamura (Kuma Kogen Astronomical Observatory, Japan)

This CCD image was taken on 1998 October 21.54 UT, using a 0.60-m f/6 Ritchey-Chretien telescope.


Jean Mueller (Palomar Observatory, California, USA) first announced the discovery of this comet on 1998 October 17. She found it on plates exposed on October 14.26 with the 1.2-m Oschin Schmidt telescope in the course of the Palomar Outer Solar System Ecliptic Survey. The magnitude was estimated as 17 and the comet exhibited a strong condensation and a faint tail. The comet was confirmed by R. Gal (Palomar Observatory) on October 17. Upon receiving information about the new discovery, G. V. Williams (Central Bureau for Astronomical Telegrams) noted that the rate and direction of motion was similar to a minor planet reported by the Lincoln Laboratory Near Earth Asteroid Research team (LINEAR) in New Mexico. This object has been found on CCD images exposed on September 26 and 27. They had estimated the magnitude as between 18.1 and 18.6. The identity of the LINEAR and Mueller objects was quickly confirmed by J. Tiché and M. Tichy (Klet Observatory) on October 17. They noted the object appeared diffuse, with a coma near 13 arcsec in diameter and a faint tail extending about 30 arcsec toward PA 210°. Following an improvement of the orbit, Williams found that the comet had been detected on September 17 by the Lowell Observatory Near-Earth Object Search (LONEOS). It had then been reported as a minor planet of magnitude 17.3.

Historical Highlights

  • Brian G. Marsden (Central Bureau for Astronomical Telegrams) published the first orbit on October 19. It was elliptical and showed the comet was moving in a short-period orbit. The perihelion date was given as 1998 November 3.18, the perihelion distance was 2.55 AU, and the orbital period was 9.14 years. The orbit indicated the comet had passed 0.11 AU from Jupiter during 1992 September. Later orbits covering several months of observations indicated little change from this initial orbit, with the perihelion date given as November 2.74, the perihelion distance given as 2.55 AU, and the orbital period given as 9.13 years.
  • Longer exposure images revealed the comet was probably brighter than 15th magnitude at discovery. Although the distance from Earth increased during the following months, the comet slowly brightened as it approached the sun. The comet's peak brightness came during November and December when several observers estimated the magnitude as 14 or slightly brighter.
  • Additional Images

    James V. Scotti image of 188P exposed on 1998 December 14
    Copyright © 1998 by J. V. Scotti (SPACEWATCH, Arizona, USA)

    This image was taken by J. V. Scotti on 1998 December 14. He used a 0.9-m Spacewatch telescope. The image is the result of three combined exposures and measures 5.7 by 6.3 arcmin. North is at the top and west to the right.