2012CBET.2992....1Z

W. Zheng, University of Michigan; J. Vinko, University of Szeged; G. H. Marion, Harvard-Smithsonian Center for Astrophysics; R. Quimby, IPMU, University of Tokyo; N. Whallon, A. Romadan, N. Wagner, and C. Akerlof, University of Michigan; F. Yuan, Australian National University; 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 15.5) in unfiltered images taken on Jan. 18.33 UT with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. The transient was observed again at mag about 15.6 on Jan. 20.33, with no detection before Jan. 6 down to a limiting magnitude of about 18.0. The new object is located at R.A. = 13:00:39.99, Decl. = +27:55:24.4 (equinox 2000.0; uncertainty about 1"), which is 3".1 east and 1".8 south of the proposed host galaxy (NGC 4906, whose redshift is z = 0.0251; Rines et al. 2003, A.J. 126, 2152, via the SIMBAD website); a finding chart is posted at the following website URL: http://www.rotse.net/rsvp/j130040.0+275524/ROTSE3_J130040.0+275524.jpg