Electronic Telegram No. 2302 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 2010dp Further to CBET 2296, M. Catelan, Pontificia Universidad Catolica de Chile; A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; R. McNaught and G. Garradd, Australian National University; J. L. Prieto, Carnegie Observatories; and E. C. Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of Arizona, report the CRTS discovery of a supernova in unfiltered Siding Spring Survey images: SN 2010 UT R.A. (2000.0) Decl. Mag. Offset 2010dp May 18.42 9 32 03.70 - 5 53 38.1 16.7 1".8 S Further magnitudes for 2010dp: Apr. 13.13 UT, [19.2 (Catalina Sky Survey); May 30.12, 17.0 (J. Brimacombe, Cairns, Australia; unfiltered images taken remotely with a telescope near Mayhill, NM, U.S.A.). A spectrogram (range 380-920 nm) of 2010dp was obtained with the SMARTS 1.5-m telescope on June 1.97; cross-correlation with a library of supernova spectra using the "SuperNova IDentification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows 2010dp to be similar to the type-Ia supernova 1999aa at one month past maximum light. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 June 3 (CBET 2302) Daniel W. E. Green