Electronic Telegram No. 958 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 2007cf IN MCG +02-39-21 S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics report that a spectrogram (range 350-740 nm) of 2007cf (cf. CBET 954), obtained by W. Peters on May 10.29 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around one week past maximum light. Cross-correlation with a library of supernova spectra indicates that 2007cf is most similar to the subluminous type-Ia supernova 1999by at 8 days past maximum. Adopting a recession velocity of 9873 km/s for the host galaxy (from Smith et al. 2004, A.J. 128, 1558), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 9500 km/s. Assuming that the galaxy is in the Hubble flow and the supernova suffers negligible extinction, the discovery magnitude of 17.9 corresponds to an absolute magnitude of roughly -17.8, which confirms the subluminous nature of the event. J. M. Silverman, T. N. Steele, and A. V. Filippenko, University of California, Berkeley, report that inspection of CCD spectra (range 330-1020 nm), obtained on May 10 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory, shows that 2007cf is a type-Ia supernova approximately 1 week past maximum brightness. Removing the host-galaxy recession velocity of 9873 km/s (Smith et al. 2004, A.J. 128, 1558), the minimum of the Si II 635.5-nm absorption feature is found to be blueshifted by about 9300 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars.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 May 10 (CBET 958) Daniel W. E. Green