Electronic Telegram No. 251 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://cfa-www.harvard.edu/iau/cbat.html SUPERNOVA 2005gm IN NGC 1423 P. Luckas, Perth, W. Australia; O. Trondal, Oslo, Norway; and M. Schwartz, Patagonia, AZ, report the discovery of an apparent supernova (mag 18.0) on unfiltered CCD frames taken with the 0.35-m telescope at Perth on Oct. 9.86 UT and the 0.81-m telescope at Patagonia on Oct. 12.38 in the course of the Tenagra Observatory Supernova Search. SN 2005gm is located at R.A. = 3h42m39s.30, Decl. = -6o23'04".0 (equinox 2000.0), which is 12".5 west and 8".9 south of the center of NGC 1423 (which has position end figures 40s.14, 22'55".1). Nothing was visible at the position of 2005gm on an image taken by Schwartz on 2004 Oct. 16.31 (limiting magnitude about 19.0) using the 0.81-m Tenagra telescope at Patagonia. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2005 CBAT 2005 October 12 (CBET 251) Daniel W. E. Green