C/2011 L4 (PANSTARRS)
＜パンスターズ 彗星＞(2013)

Discovered by Richard Wainscoat (Institute for Astronomy, University of Hawaii) on four CCD images taken with the 1.8-m "Pan-STARRS 1" telescope at Haleakala taken on 2011 June 6; the object then appeared to show slight non-stellar appearance and was said to be around magnitude 19. Three follow-up 30-s r-band exposures were then acquired by M. Micheli and Wainscoat with the Canada-France-Hawaii Telescope on Mauna Kea (queue observer Lisa Wells) on June 7.44 UT, showing that a coma was definitely visible with a subtle hint of a faint tail towards p.a. 60 deg. The comet was designated as comet C/2011 L4 (PANSTARRS) when it was formally announced by the Central Bureau for Astronomical Telegrams on its IAU Circular No. 9215.

The 1.8-m Pan-STARRS 1 Ritchey-Chretien telescope (Haleakala, Hawaii, USA) discovered this comet on four CCD images acquired during 2011 June 6.39-6.43. The magnitude was given as 19.4-19.6.
Several prediscovery images have been found. S. Larson (Mt. Lemmon Survey, Arizona, USA) reported that C/2011 L4 was located on four images acquired using the 154-cm reflector and a CCD camera during May 24.31-24.33. He gave the magnitude as 18.9-19.2. Hidetaka Sato (Tokyo, Japan) had acquired two images of periodic comet 174P on May 30 using his 25-cm reflector and a CCD camera. After the discovery of C/2011 L4, he noted it had passed rather close to 174P. Upon rechecking his images, he located the new comet glowing at magnitude 18.6-18.8. The comet had reached a maximum solar elongation of 176 degrees on May 27. Around mid-June, four additional images of the comet were located on images that had been acquired by Pan-STARRS 1 during May 21.43-21.48. The magnitude was given as 19.5-19.9.

パンスターズ彗星（C/2011 L4 (PANSTARRS) ）は、2011年6月6日（世界時）に、米国ハワイ州・マウイ島のハレアカラに設置されたパンスターズ1 望遠鏡による観測で発見されました。発見時は、さそり座方向にあり明るさは19.4等で、恒星とは異なる形状で観測されましたが、その後、ハワイ島マウナケアにあるカナダ・フランス・ハワイ望遠鏡（CFHT）をはじめとする他の望遠鏡による確認観測の結果、彗星の特徴であるコマと尾があらためて確認されました。発見時のパンスターズ彗星までの距離は約6.9天文単位、木星の軌道よりも遠い位置でした。（IAUC No.9215, 2011 June 8 より）