Electronic Telegram No. 784 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://cfa-www.harvard.edu/iau/cbat.html SUPERNOVA 2006su IN IC 3772 S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrum (range 350-740 nm) of 2006su (cf. CBET 782), obtained on Dec. 24.53 UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around 3-4 weeks past maximum light. Cross-correlation with a library of type-Ia supernova spectra indicates that 2006su is most similar to SN 2000cf (cf. IAUC 7423) at 26 days past maximum. Narrow emission lines from the host galaxy are detected at a redshift of cz = 14036 +/- 47 km/s. R. J. Foley and A. V. Filippenko, University of California, Berkeley, report that inspection of CCD spectra (range 450-950 nm), obtained on Dec. 23 UT with the Keck II 10-m telescope (+ DEIMOS), shows that 2006su is a type-Ia supernova, roughly 3-4 weeks after maximum brightness. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 December 25 (CBET 784) Daniel W. E. Green