Electronic Telegram No. 2483 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 APPARENT NOVA IN M31: M31N 2010-10a Koichi Nishiyama, Kurume, Japan; and Fujio Kabashima, Miyaki, Japan, report the discovery of a possible nova (mag 17.9) in M31 on seven 40-s unfiltered CCD frames (limiting magnitude 19.6) taken around Oct. 05.551 UT using a Meade 200R 0.40-m f/9.8 reflector (+ SBIG STL1001E camera). They confirmed the variable on images (limiting mag 19.7) taken on Oct. 6.538, when the new object had brightened to mag 17.1. The apparent nova, designated M31N 2010-10a, is located at R.A. = 0h42m45.82, Decl. = +41d24'22".0 (equinox 2000.0), which is 17" east and 493" north of the center of the galaxy M31. Nothing is visible at this position on their past frames taken on Sept. 30.560 and Oct. 1.542 (limiting magnitude 19.2) or on the Digitized Sky Survey from 1986 Nov. 27 (limiting red mag 18.7) and 1993 Oct. 21 (limiting infrared mag 17.9). T. Yusa, Osaki, Japan, reports that M31N 2010-10a was at mag 17.3 on unfiltered CCD frames (limiting mag 19.3) taken on Oct. 6.188, remotely using a 0.25-m f/3.4 reflector (+ SBIG ST-10XME camera) at the RAS Observatory near Mayhill, NM, U.S.A.; he measured position end figures 45s.82, 22".3 (offset 16" east, 497" north). Yusa's image is posted at the following website URL: http://space.geocities.jp/yusastar77/PNinM31_101006.htm. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 October 7 (CBET 2483) Daniel W. E. Green