Electronic Telegram No. 3264 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 C/2012 U1 (PANSTARRS) Richard Wainscoat and Marco Micheli, University of Hawaii, report the discovery of a comet in three w-band exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala (discovery observations tabulated below), noting the object to appear slightly extended relative to adjacent field stars. Micheli and Wainscoat later obtained three follow-up 120-s r-band exposures on Oct. 19 using the Canada-France-Hawaii Telescope (queue observer Lisa Wells), in which the object was seen to be clearly extended, but circularly symmetric with no sign of a tail (FWHM of the comet measured to be approximately 1".1, while that of adjacent stars was measured to be 0".75); at the time of the observation, the object moved across a very faint background galaxy, though it is not believed that the background galaxy contributed significantly to the extension of the point-spread function PSF of the comet. After posting on the Minor Planet Center's NEOCP webpage, other CCD astrometrists have also commented on the object's cometary appearance. H. Sato (Tokyo, Japan; remotely using a 0.43-m f/6.8 astrograph at the RAS Observatory near Mayhill, NM, U.S.A.; Oct. 20.3 UT) found a diffuse coma of diameter 18" with total V-band magnitude 19.8 as measured within a circular aperture of radius 9".5. E. Guido, N. Howes, A. Tripp, and G. Sostero write that five stacked 120-s R-band images taken with the 2.0-m f/10 "Faulkes Telescope North" at Haleakala on Oct. 22.45 under good seeing conditions show a diffuse coma nearly 5" in diameter. 2012 UT R.A. (2000) Decl. Mag. Oct. 18.31653 1 53 13.66 +22 50 31.4 21.0 18.32907 1 53 13.19 +22 50 32.4 21.0 18.34161 1 53 12.75 +22 50 33.4 21.1 The available astrometry (including prediscovery Mount Lemmon Survey observations from Oct. 17.4), the following preliminary parabolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2012-U66. T = 2014 June 30.9696 TT Peri. = 58.0360 Node = 29.1949 2000.0 q = 6.316809 AU Incl. = 66.7319 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2012 CBAT 2012 October 22 (CBET 3264) Daniel W. E. Green