Electronic Telegram No. 1538 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://www.cfa.harvard.edu/iau/cbat.html SUPERNOVA 2008gg Further to CBET 1526, A. J. Drake reports, on behalf of his colleagues, the discovery of an apparent supernova (mag 16.3) on an unfiltered Catalina Sky Survey (CSS) image taken on Oct. 9.31 UT, giving the position of the new object as R.A. = 1h25m23s.0, Decl. = -18o10'20" (equinox 2000.0); nothing was visible at this position on a CSS image from 2007 Nov. 11 (limiting mag 19.5). T. Kryachko, Kazan State University Astrotel Observatory, Karachay-Cherkessia, Russia; and S. Korotkiy, Ka-Dar Observatory, write that 2008gg appears at mag 16.4 on unfiltered CCD images obtained on Oct. 10.010 with a Takahashi 30-cm f/7.8 telescope (+ Apogee Alta U9000 CCD camera), measuring its position to be R.A. = 1h25m23s.04 +/- 0".1, Decl. = -18d10'20".8 +/- 0".1, which is about 18".7 east and 30".7 south of center of the galaxy NGC 539. They add that nothing is visible at this position on a Palomar Sky Survey (SERC-J) plate obtained on 1980 Oct. 13 (via the Digitized Sky Survey; limiting mag 21.0). Following posting on the Central Bureau's unconfirmed-objects webpage, C. Jacques and E. Pimentel (Belo Horizonte, Brazil) report that a 60-s unfiltered CCD image (limiting mag 17.5) taken on Oct. 13.01 with a 30-cm f/3.3 Schmidt-Cassegrain reflector at CEAMIG-REA Observatory yields mag 16.6 and position end figures 23s.07, 20".5; they add that nothing is visible at this position on a red DSS image from 1990 Sept. 15 (limiting magnitude 19.5). S. Nakano, Sumoto, Japan, writes that K. Itagaki (Yamagata, Japan, 0.60-m f/5.7 reflector) found mag 16.8 and position end figures 23s.04, 20".5 from an unfiltered CCD image (limiting mag 18.0) taken on Oct. 13.663. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 October 13 (CBET 1538) Daniel W. E. Green