Electronic Telegram No. 1155 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 2007rw IN UGC 7798 S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrogram (range 350-740 nm) of 2007rw (cf. CBET 1154), obtained by P. Berlind on Dec. 4.55 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-IIb supernova around three weeks past explosion. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2007rw is most similar to SN 1993J at 18 days past explosion (Matheson et al. 2000, A.J. 120, 1487). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 December 4 (CBET 1155) Daniel W. E. Green