Electronic Telegram No. 2371 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 2010gg IN ESO 602-25 J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, P. Gonzalez, S. Silva, G. Folatelli, R. Cartier, F. Forster, and S. Marchi, Universidad de Chile; G. Pignata and M. Cifuentes, Universidad Andres Bello; B. Conuel, Wesleyan University; and D. Reichart, K. Ivarsen, J. Haislip, A. Crain, D. Foster, M. Nysewander, and A. LaCluyze, University of North Carolina at Chapel Hill, on behalf of the CHASE project, report the discovery of an apparent supernova (mag approximately 17.7) on an unfiltered image taken on July 12.31 UT with the 0.41-m 'PROMPT 3' telescope located at Cerro Tololo. The new object, which is also present at mag approximately 17.5 in an image taken on July 13.30, is located at R.A. = 22h31m25s.47 +/- 0".1, Decl. = -19o01'54".8 +/- 0".1 (equinox 2000.0), which is about 0".1 east and 9".5 north of the center of the galaxy ESO 602-25. Nothing is visible at this position on archival images taken on June 22.24 (limiting mag 17.0) and in a stack of twenty-three 40-s images taken between 2009 Apr. 13.39 and 2010 May 7.36 (limiting mag 20.5). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 July 14 (CBET 2371) Daniel W. E. Green