78P/＜Gehrels 2 彗星＞(2012)

＊　ゲーレルス第2彗星がよいの南の空に！　＊ Discovery Tom Gehrels (Lunar and Planetary Laboratory, Arizona, USA) discovered this comet while examining plates exposed with Palomar Observatory's 122-cm Schmidt Telescope during a minor planet survey. The comet's diffuse image was noted on plates exposed on 1973 September 29, September 30, October 4, and October 5. The brightness was estimated as 15-16, while a fan-shaped tail extended about 2 arc minutes. The comet was officially announced on October 31, at which time B. G. Marsden (Central Bureau for Astronomical Telegrams) provided both a parabolic and elliptical orbit. The latter indicated an orbital period of 8.76 years. This orbit allowed numerous immediate observations, and the short-period nature of the orbit was confirmed on November 7 when Marsden issued a more precise orbit indicating a perihelion date of 1973 November 30 and an orbital period of 7.93 years. This orbit indicated the comet had passed 0.9 AU from Jupiter in 1971, and that prior to that encounter the orbital period had been 8.5 years. A prediscovery image was identified in early November. This image was identified by E. Helin (California Institute of Technology, USA) on a plate exposed with the Palomar Observatory 46-cm Schmidt telescope on September 28. The brightness was estimated as magnitude 16.

from　G A R Y W. K R O N K ' S C O M E T O G R A P H Y
http://cometography.com/lcomets/078p.html