Electronic Telegram No. 2113 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://www.cfa.harvard.edu/iau/cbat.html COMET C/2010 A1 (HILL) R. E. Hill, Lunar and Planetary Laboratory, reports a cometary object (discovery observation below) with the 0.68-m Schmidt at the Catalina Sky Survey; in 2-4-arcsec seeing and moonlight, there was a 4-5-arcsec condensation and a coma 10-15-arcsec across, with no obvious tail. Four coadded images obtained by E. C. Beshore with the Mt. Lemmon 1.5-m reflector on Jan. 6.5 UT showed a very faint tail in p.a. 270 deg and perhaps 15" in length. After the discovery had been added to the NEO Confirmation Page, Y. Ikari (Moriyama, Japan, 0.26-m f/7.0 reflector, Jan. 6.6) reported a 0'.2 coma; P. Birtwhistle (Great Shefford, Berkshire, England, 0.40-m f/6.0 Schmidt-Cassegrain, Jan. 7.1) described a weak condensation offset to the southeast of a 15" by 22" coma, with the brightest part of the coma 6" by 12" extending in p.a. 50 and 230 deg; and H. Sato (RAS Observatory, Mayhill, NM, U.S.A., 0.25-m f/3.4 reflector, Jan. 7.2) mentioned a 20" coma elongated in p.a. 110 deg. On Jan. 7.2, Hill detected a short, fan-shaped tail, 20-30-arcsec long, in p.a. 270 deg. 2010 UT R.A. (2000) Decl. Mag. Observer Jan. 6.46381 09 11 26.44 +33 08 34.6 17.6 Hill Further astrometry, the following parabolic orbital elements and an ephemeris are given on MPEC 2010-A31. It is possible that the comet is of short period. T = 2010 June 24.055 TT Peri. = 219.047 Node = 6.140 2000.0 q = 1.02031 AU Incl. = 11.782 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 January 7 (CBET 2113) Brian G. Marsden