Electronic Telegram No. 545 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 2006da Further to IAUC 8622, R. Quimby, University of Texas, reports the discovery of an apparent supernova in unfiltered CCD images taken on June 12.41 (at mag about 16.6), and 13.41 UT (mag about 16.8) using the 0.45-m ROTSE-IIIb telescope at the McDonald Observatory. SN 2006da is located at R.A. = 23h27m48s.57, Decl. = +14o28'27".0 (equinox 2000.0), which is 1".5 west and 4".2 south of the center of the apparent host galaxy (catalogued redshift of z = 0.041 from the Sloan Digital Sky Survey). The new object was found by subtracting a co-addition of images taken between 2005 July 15 and 2005 Sept. 12 (limiting mag about 18.8) from the 2006 June images. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 June 15 (CBET 545) Daniel W. E. Green