Electronic Telegram No. 2811 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network COMET P/2011 R2 (PANSTARRS) Larry Denneau and Richard Wainscoat, Institute for Astronomy, University of Hawaii, report the discovery of a comet on two i-band Pan-STARRS images taken with the 1.8-m "Pan-STARRS 1" telescope at Haleakala (discovery observation tabulated below), the object having a central condensation and being distinctly extended with an extension to the west that appears to be a faint tail. Richard Wainscoat and Marco Micheli obtained r-band observations with the Canada-France Hawaii Telescope on Sept. 6 UT that show the object to be distinctly non-stellar, with a tail in p.a. approximately 257 degrees that extends for 15" from the nuclear condensation. After posting on the Minor Planet Center's NEOCP webpage, numerous other CCD astrometrists have commented on the object's cometary nature. 2011 UT R.A. (2000) Decl. Mag. Sept. 4.50500 23 31 05.15 - 6 30 28.4 18.7 The available astrometry, the following preliminary elliptical orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2011-R24. T = 2011 Nov. 19.509 TT Peri. = 230.124 e = 0.40398 Node = 146.442 2000.0 q = 2.01652 AU Incl. = 4.771 a = 3.38328 AU n = 0.158379 P = 6.22 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 September 7 (CBET 2811) Daniel W. E. Green