Electronic Telegram No. 898 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 2007at AND 2007au S. Blondin, M. Hicken, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that spectra (range 350-740 nm) of 2007at (cf. CBET 893) and 2007au (cf. CBET 895), obtained on Mar. 19.45 and 19.27 UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows them to be both type-Ia supernovae. Cross-correlation with a library of supernova spectra shows that 2007at is most similar to SN 1989B at 9.5 days past maximum light, and that 2007au is most similar to SN 1992A (Kirshner et al. 1993, Ap.J. 415, 589) at one day before maximum. Adopting a recession velocity of 16262 km/s for the host galaxy of 2007at (from Fouque et al. 1992, Catalogue of Optical Radial Velocities, vol. 1), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 11500 km/s. Adopting a recession velocity of 6164 km/s for the host galaxy of 2007au (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(rest 635.5 nm) is blueshifted by roughly 13000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars.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 March 19 (CBET 898) Daniel W. E. Green