Electronic Telegram No. 4021 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/2014 W4 (PANSTARRS) R. J. Wainscoat reports the discovery of a comet in four w-band CCD exposures taken with the 1.8-m Pan-STARRS1 telescope at Haleakala on Nov. 18 (discovery observations tabulated below); the object has a diffuse appearance with a short tail extending for approximately 2" in p.a. 200 degrees. 2014 UT R.A. (2000) Decl. Mag. Nov. 18.50270 3 00 11.23 +23 10 13.0 20.7 18.51538 3 00 10.77 +23 10 12.4 20.6 18.52805 3 00 10.31 +23 10 12.1 20.5 18.54073 3 00 09.84 +23 10 11.7 20.7 Wainscoat and M. Micheli report that three 60-s r-band follow-up exposures, tracked at the rate of the comet by Wainscoat and A. Draginda with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on Nov. 19.4 UT, show a 4" tail to the southwest with a small coma (FWHM about 1".1 in 0".65 seeing) of magnitude 20.3-20.7. After the object was posted on the Minor Planet Center's PCCP webpage, other CCD astrometrists have also commented on the object's cometary appearance. W. H. Ryan (Magdalena Ridge Observatory 2.4-m f/8.9 reflector + R-band filter) notes a small coma of magnitude 19.7-19.8 that is slightly larger than nearby stars of similar brightness and a small tail toward p.a. about 225 deg on Nov. 19.23-19.26. H. Sato, Tokyo, Japan, writes that twelve stacked 60-s exposures taken with an iTelescope 0.51-m f/6.8 astrograph (+ luminance filter) at Siding Spring on Nov. 19.6 shows the comet to be strongly condensed with a faint outer coma 10" in diameter (w-band magnitude 19.5 as measured within a circular aperture of radius 6".6) with no tail. The available astrometry (including pre-discovery Pan-STARRS1 observations from Oct. 25.6 UT, with the comet reported then at mag 20.8-21.3; identified by T. Spahr), the following preliminary elliptical orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2014-W57. Epoch = 2016 Jan. 13.0 TT T = 2015 Dec. 26.1230 TT Peri. = 67.7623 e = 0.363188 Node = 33.1955 2000.0 q = 4.231388 AU Incl. = 15.1262 a = 6.644646 AU n = 0.0575435 P = 17.1 years NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2014 CBAT 2014 November 21 (CBET 4021) Daniel W. E. Green