[IAUC] CBET 859: 20070225 : SUPERNOVAE 2007ac AND 2007ae

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                                                  Electronic Telegram No. 859
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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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.


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                         (C) Copyright 2007 CBAT
2007 February 25                 (CBET 859)               Daniel W. E. Green