Electronic Telegram No. 2160 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Room 209; Dept. of Earth and Planetary Sciences; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbat@cfa.harvard.edu; dwe_green@eps.harvard.edu URL http://www.cfa.harvard.edu/iau/cbat.html COMET 29P/SCHWASSMANN-WACHMANN J. M. Trigo-Rodriguez, Consejo Superior de Investigaciones Cientificas and Institut d'Estudis Espacial de Catalunya, suggests that comet 29P is currently experiencing an unusual outburst. His analysis of multi-band images taken on Feb. 3.181 UT by A. Sanchez (Gualba, Spain, 0.31-m reflector) shows a stellar appearance with an apparent diameter of 15" and the following magnitudes measured through a 10" aperture: V = 11.9, R = 11.7, I = 11.5. F. Colas and L. Maquet, IMCCE, Observatoire de Paris, report that resolved coma images obtained with the Pic du Midi 1-m reflector) on Feb. 3.96 show a coma diameter of 10"; when combined with a typical ejection velocity of 300 m/s, this suggests that the outburst occurred around Feb. 2.52. Additional observations obtained in the last month suggest a progressive increase in activity since mid-January, from an inactive 40-day period in which the comet remained close to R magnitude 16 in a 10" aperture. Additional recent 10"- aperture magnitudes for comet 29P supplied by Trigo-Rodriguez: 2009 Dec. 20.04, R = 16.4 (Trigo-Rodriguez, Montseny, Spain, 0.18-m reflector); Dec. 25.25, R = 16.1, I = 15.9 (Sanchez); 2010 Jan. 9.97, V = 15.7, R = 15.0, I = 15.4 (S. Pastor and J. A. Reyes, Molina de Segura, Spain, 0.40-m reflector); Jan. 10.07, R = 15.6 (Sanchez); Jan. 12.19, R = 15.7 (Sanchez); Jan. 27.18, R = 15.2 (Sanchez); Jan. 27.18, R = 15.1, I = 15.2 (D. Rodriguez, Villalba- Madrid, Spain, 0.25-m reflector). Colas provides the following additional magnitudes for 29P: Feb. 3.87, R = 11.6 (F. Kugel, Chante Perdrix Observatory, Dauban, France; 0.20-m presumed); Feb. 4.02, R = 11.7 (Pic du Midi). Recent visual total-magnitude and coma-diameter estimates reported to the Central Bureau: 2009 Sept. 23.19 UT, 11.7, 0'.7 (J. J. Gonzalez, Leon, Spain, 0.20-m reflector); 29.20, 11.5, 1'.5 (Gonzalez); Oct. 26.21, 11.3, 3' (Gonzalez; zodiacal light); Nov. 14.28, 11.9, 1'.5 (M. Goiato, Aracatuba, Brazil, 0.22-m reflector); 18.11, 11.8, 0'.6 (Gonzalez); 24.14, 11.9, 1'.5 (Gonzalez); 25.72, 13.2, 0'.8 (C. Wyatt, Walcha, NSW, Australia, 0.25-m reflector); Dec. 12.15, 12.0, 2' (J. J. Gonzalez, Leon, Spain, 0.20-m reflector); Feb. 4.06, 11.5, 0'.4 (Goiato). Recent total unfiltered CCD magnitude estimates submitted by K. Kadota (Ageo, Saitama-ken, Japan, 0.25-m reflector) in the course of his cometary astrometry program: 2009 Oct. 30.80, 13.2; Nov. 30.75, 12.8; Dec. 30.66, 12.0; 2010 Jan. 11.68, 13.6. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 February 4 (CBET 2160) Daniel W. E. Green