Electronic Telegram No. 2852 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/2011 S2 R. A. Kowalski reports the discovery of a comet on CCD images obtained with the Catalina Sky Survey's 0.68-m Schmidt reflector (discovery observations tabulated below), the object described as having a bright, condensed coma 15" in diameter with a broad tail at least 1' long in p.a. 300 deg. Follow-up observations by A. R. Gibbs with the Mt. Lemmon 1.5-m reflector on Oct. 1.51 UT show a 55" tail in p.a. 300 deg. After posting on the Minor Planet Center's NEOCP webpage, other CCD astrometrists have commented on the object's cometary appearance. E. Pettarin (Farra d'Isonzo, Italy, 0.40-m f/4.5 reflector; Oct. 1.1) measures a 60" tail in p.a. 300 deg. A. Knoefel (Drebach, Germany, 0.5-m f/5 reflector; Oct. 1.1) finds a 2' tail. L. Buzzi (Varese, Italy, 0.60-m f/4.6 reflector; Oct. 1.1) reports a condensed coma 12" in size with a tail at least 60" long in p.a. around 296 deg. P. Birtwhistle (Great Shefford, Berkshire, England, 0.40-m f/6 Schmidt-Cassegrain reflector; Oct. 1.2) notes a concentrated coma of diameter 10" and total mag 16.4, with a fan tail spanning p.a. 238-326 deg, having a brighter central spine 1'40" long in p.a. 300 deg. Images taken by R. Holmes (Ashmore, IL, USA, 0.61-m f/4 astrograph; Oct. 1.4) and measured by T. Vorobjov, L. Buzzi, and S. Foglia reveal a 10" x 15" coma elongated in p.a. 290 deg with a tail 1'-2' long in the same position angle. E. Guido, G. Sostero, and N. Howes (0.25-m f/3.4 reflector remotely at the GRAS Observatory near Mayhill, NM, U.S.A.; Oct. 1.4) report a condensed coma about 10" in diameter that is elongated toward p.a. 295 deg. H. Sato (Tokyo, Japan; remotely using a 0.51-m f/4.5 reflector at the GRAS Observatory near Mayhill; Oct. 1.5) finds a coma of diameter 25" with a tail; the total red mag was 16.0 in a circular aperture of radius 13". S. Baroni, L. Buzzi, P. Concari, S. Foglia, G. Galli, and M. Tombelli write that four stacked 180-s images obtained with a 0.18-m f/2.8 Newtonian reflector on Oct. 1.5 show a round coma of diameter 12". R-band images taken by W. H. Ryan and E. V. Ryan (Magdalena Ridge Observatory, 2.4-m f/8.9 reflector) reveal a prominent tail at p.a. about 335 deg on Oct. 1.5 and p.a. about 300 deg on Oct. 2.5. G. Hug (Scranton, KS, U.S.A., 0.56-m reflector; Oct. 2.5) reports a narrow, fan-shaped tail extending 2'.5 in p.a. about 300 deg. 2011 UT R.A. (2000) Decl. Mag. Observer Sept.30.48411 9 12 10.05 +20 18 30.3 15.7 Kowalski 30.48640 9 12 10.68 +20 18 24.6 15.7 " 30.48868 9 12 11.12 +20 18 20.3 15.7 " 30.49094 9 12 11.83 +20 18 15.9 15.7 " The available astrometry, the following preliminary parabolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2011-T12. The orbit of this object is essentially indeterminate at the present time. It is possible that this is a short-period comet. Among the wide range of possible short- period orbits are orbits that appear similar to that of P/2006 T1 (Levy). Initial attempts to link the two apparitions have not been successful. Further observations are encouraged. T = 2011 Oct. 23.524 TT Peri. = 188.828 Node = 288.573 2000.0 q = 1.13259 AU Incl. = 17.319 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 October 3 (CBET 2852) Daniel W. E. Green