[IAUC] CBET 939: 20070423 : SUPERNOVA 2007bm IN NGC 3672

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                                                  Electronic Telegram No. 939
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2007bm IN NGC 3672
     H. Navasardyan, S. Benetti, A. Harutyunyan, and M. Turatto, Istituto
Nazionale di Astrofisica and Osservatorio Astronomico di Padova, report
that a spectrogram (range 350-780 nm, resolution 2.2 nm) of 2007bm (cf.
CBET 936), obtained on Apr. 22.90 UT with the Ekar-Copernicus 1.82-m
telescope (+ AFOSC), shows it to be a type-Ia supernova.  Assuming a
recession velocity of 1866 km/s (from LEDA) for the host galaxy, the
'PASSparToo' spectrum-comparison code (Harutyunyan et al. 2005, ASP Conf.
Ser. 342, 258) provides good fits to spectra of type-Ia supernovae around
a week before B-maximum light, once the spectrum is corrected for
extinction as derived from an intense (EW about 0.26 nm) Na I D
interstellar absorption doublet.  The phase is confirmed by the expansion
velocity deduced from the Si II 635.5-nm absorption feature (about 12500
km/s).


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                         (C) Copyright 2007 CBAT
2007 April 23                    (CBET 939)               Daniel W. E. Green