Copyright © 1998 by Akimasa Nakamura
The CCD image was taken at Kuma Kogen Astronomical Observatory on 1998 December 17, using a 0.60-m f/6 Ritchey-Chretien telescope.
Discovery
The discovery of this comet was a long time coming. During a routine asteroid search program at Turku, Yrjö Väisälä found this object on 1939 October 7.91 in Aries. The object was classed as an asteroid and designated 1939 TN. The magnitude was determined as 15.8. The object was further photographed on October 18.88 and 20.85. The fourth and final observation came on November 11.74. Precise positions were not published until 1979 and an orbit calculation by Liisi Oterma suggested the object was a comet. In addition, she communicated to the Central Bureau for Astronomical Telegrams in 1981 that a reexamination of the plates suggested the object was somewhat diffuse.
The LINEAR program discovered an apparent asteroidal object on 1998 November 18.26. Three additional positions were obtained on the 18th and three more were obtained on November 21. The object was given the asteroidal designation 1998 WG22. S. Nakano subsequently noted the orbit was similar to that of 1939 TN, and he successfully linked the two apparitions. D. Balam (Dominion Astrophysical Observatory) observed the object on December 6.3 using a 1.8-m reflector and noted a coma 8 arc seconds across and a tail extending 18 arc seconds toward PA 260 degrees.
Historical Highlights