Electronic Telegram No. 539 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 2006cs IN MCG +06-30-79 S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrum (range 350-740 nm) of 2006cs (cf. CBET 536), obtained on June 5.29 UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around maximum light. Cross-correlation with a library of type-Ia-supernova spectra indicates that 2006cs is most similar to the subluminous supernova 1999by (see Garnavich et al. 2004, Ap.J., 613, 1120) at -3 days. Adopting a recession velocity of 7026 km/s for the host galaxy (from "The Updated Zwicky Catalog", http://tdc-www.harvard.edu/uzc/), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 10500 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 June 5 (CBET 539) Daniel W. E. Green