Electronic Telegram No. 978 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 2007co IN MCG +05-43-16 S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrum (range 350-740 nm) of 2007co (cf. CBET 977), obtained on June 8.35 UT by M. Calkins with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around one week before maximum light. Cross-correlation with a library of supernova spectra indicates that 2007co is most similar to the type-Ia supernova 1997dt at 7 days before maximum light. Adopting a recession velocity of 8083 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(rest 635.5 nm) is blueshifted by roughly 13000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 June 8 (CBET 978) Daniel W. E. Green