Electronic Telegram No. 2309 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@iau.org; cbatiau@eps.harvard.edu URL http://www.cfa.harvard.edu/iau/cbat.html SUPERNOVA 2010dv IN NGC 3903 L. A. G. Monard, Pretoria, South Africa, reports his discovery of an apparent supernova (mag 17.5 +/- 0.5) on unfiltered CCD images taken on June 4.723, 5.695, 5.754, and 6.716 UT. The new object is located at R.A. = 11h49m03s.43, Decl. = -37d30'59".7 (equinox 2000.0), which is 2" west and 2" north of the core of the galaxy NGC 3903. Nothing is seen at this position in red Digitized Sky Survey images down to mag 20.5, on the previous image of this galaxy taken at Monard's Bronberg Observatory on 2010 May 4.776 (limiting mag 19.0), or on earlier images from there. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 June 8 (CBET 2309) Daniel W. E. Green