Electronic Telegram No. 859 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 SUPERNOVAE 2007ac AND 2007ae S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrogram (range 350-740 nm) of SN 2007ac (cf. CBET 854), obtained by A. Vaz on Feb. 25.54 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-II supernova roughly 1-2 weeks past explosion. The spectrum consists of a blue continuum and P-Cyg lines of the Balmer series, consistent with the plateau phase of a normal type-II supernova. The spectrum is similar to the type-II-plateau supernova 1999em at 10 days past explosion. Adopting a recession velocity of 9056 km/s for the host galaxy (Rines et al. 2002, A.J. 124, 1266), the maximum absorption in the H_beta line (rest 486.1 nm) is blueshifted by roughly 9500 km/s. Blondin et al. add that a spectrum (range 350-740 nm) of SN 2007ae (cf. CBET 856), obtained on Feb. 25.54 by Vaz, shows it to be a type-Ia supernova around maximum light. Cross-correlation with a library of supernova spectra indicates that 2007ae is most similar to the type-Ia supernova 1999ee at maximum light. Adopting a recession velocity of 19303 km/s for the host galaxy (Berrington et al. 2002, A.J. 123, 2261), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 11000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars.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 February 25 (CBET 859) Daniel W. E. Green