Electronic Telegram No. 1639 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 2008io IN MCG -02-33-17 F. Yuan, University of Michigan; R. Quimby, California Institute of Technology; D. Chamarro and M. D. Sisson, University of Michigan; A. Uecker, Indiana University of Pennsylvania; C. Akerlof, University of Michigan; and J. C. Wheeler, University of Texas, on behalf of the ROTSE collaboration, report the discovery of an apparent supernova (mag about 16.1) in unfiltered CCD images taken on Dec. 26.09 UT with the 0.45-m ROTSE-IIIc telescope at the H.E.S.S. site in Namibia. The new object, which also was observed at mag about 16.1 on Dec. 27.10, is located at R.A. = 12h50m02s.61, Decl. = -14o42'55".7 (equinox 2000.0), which is 28".9 west and 61".1 north of the center of its apparent host galaxy, MCG -02-33-17. This field was not observed by any ROTSE-III telescope between July 2007 and the discovery date. Nothing is visible at this position in the Digitized Sky Survey images (limiting mag 20.5) or in the ROTSE reference image built from images taken between March and May 2007 (limiting mag 19.2). An image showing 2008io has been posted at the following website URL: http://www.rotse.net/rsvp/j125002.6-144256/j125002.6-144256.jpg NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 December 29 (CBET 1639) Daniel W. E. Green