Electronic Telegram No. 3159 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network SUPERNOVA 2012de V. Lipunov communicates the discovery by P. Podvorotniy, on behalf of the MASTER team, of a possible supernova (mag 18.5) on three unfiltered CCD images (limiting mag 19.2) obtained with the auto-detection system of the MASTER II 40-cm telescope (+ Apogee Alta U16m camera; field-of-view 2 x 4 square degrees) at the Kislovodsk observatory (see website URL http://observ.pereplet.ru) on June 25.952 UT. The new object is located at R.A. = 22h15m05s.32, Decl. = +10d18'12".6 (equinox 2000.0), which is 2".2 and 2".3 from the the centers of two faint SDSS8 galaxies (magnitude r > 22.5) at position end figures 05s.40, 14".2 and 05s.40, 14".3. Nothing is visible at this position on a MASTER reference image from 2010 July 16 (limiting mag 18.0). The discovery and reference images are posted at the following website URL: http://master.sai.msu.ru/static/OT/221505.31101812.5.png. J. M. Silverman, D. P. Cohen, and A. V. Filippenko, University of California, Berkeley, report that inspection of a CCD spectrum (range 340-1000 nm), obtained on June 27.4 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory, shows that 2012de is a type-Ia supernova. Cross-correlation with a library of supernovae spectra using the "SuperNova IDentification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2012de is a normal type-Ia supernova near maximum brightness at a redshift of 0.090. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2012 CBAT 2012 July 3 (CBET 3159) Daniel W. E. Green