Electronic Telegram No. 2556 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 2010kd J. Vinko, University of Szeged; W. Zheng and A. Romadan, University of Michigan; R. Quimby, California Institute of Technology; N. Whallon, S. B. Pandey, Y. Fang, and C. Akerlof, University of Michigan; P. Pasque and M. Verkinderen, Cousino High School; and J. C. Wheeler and E. Chatzopoulos, University of Texas, on behalf of the ROTSE collaboration, report the discovery of a new supernova (mag about 17.5) in unfiltered images taken on Nov. 14.49 UT with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. The new object -- which was observed again on Nov. 16.49 at mag about 17.4, on Nov. 18.48 at mag about 17.4, and on Nov. 22.47 at mag about 17.5 -- is located at R.A. = 12h08m01s.11, Decl. = +49o13'31".1 (equinox 2000.0; uncertainty about 1"), which is 2".1 east and 1".8 south of the center of the presumed host galaxy (SDSS J120800.89+491332.8). Note that there is a fainter, uncatalogued extended source about 2" southeast of the host galaxy that is also a possible candidate to be the host galaxy of the new supernova. A finding chart for the new object can be found at the following website URL: http://www.rotse.net/rsvp/j120801.1+491331/j120801.1+491331.jpg. A spectrum, obtained on Nov. 22.51 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell, shows broad, weak P-Cyg features superimposed on a blue continuum, consistent with an early type-II supernova. If the strongest broad feature is due to H-alpha, then the redshift is z about 0.1, implying a peak absolute magnitude brighter than -20.5 (neglecting interstellar extinction). According to SNID (Blondin and Tonry 2007, Ap.J. 666, 1024), the spectrum is similar to that of SN 1999gi at 5 days before maximum light at a redshift consistent with the above estimate, but no template matches all the observed features well. These suggest that the supernova may be a peculiar, super-luminous event. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 November 27 (CBET 2556) Daniel W. E. Green