Electronic Telegram No. 105 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 2005O IN NGC 3340 Y.-T. Chen, Graduate Institute of Astronomy, National Central University, Chung-Li, reports the discovery by the Taiwan Supernova Survey of an apparent supernova (mag about 16.1) on unfiltered CCD images taken on Jan. 16.780 UT with the 1-m Lulin Observatory telescope. The new object had brightened to mag about 15.2 on a confirming image taken on Jan. 20.650. SN 2005O is located at R.A. = 10h42m18s.32, Decl. = -0o22'41".2 (equinox 2000.0), which is 5".3 east and 4".8 south of the center of NGC 3340. Nothing was visible at this on an image taken on 2004 Dec. 27.855 (limiting mag about 18.6). NOTE: These 'Central Bureau Electronic Telegrams' are intended to be preliminary announcements of items that later appear in the formal IAU Circulars. Citations should normally be made to IAUCs rather than to CBETs. (C) Copyright 2005 CBAT 2005 January 21 (CBET 105) Daniel W. E. Green