[IAUC] CBET 918: 20070410 : SUPERNOVA 2007ba IN UGC 9798

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                                                  Electronic Telegram No. 918
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 2007ba IN UGC 9798
     S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics report that a spectrogram (range 350-740 nm) of SN
2007ba (cf. CBET 911), obtained by M. Calkins on Apr. 9.45 UT with the F. L.
Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia
supernova around maximum light.  Cross-correlation with a library of
supernova spectra indicates that 2007ba is most similar to the subluminous
type-Ia supernova 1999by at three days before maximum.  Adopting a recession
velocity of 11554 km/s for the host galaxy (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 10500 km/s.  Assuming that the
host galaxy is in the Hubble flow and that the supernova suffers negligible
extinction, the discovery magnitude of 18.3 corresponds to an absolute
magnitude of roughly -17.7, similar to SN 1991bg at the same phase.


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                         (C) Copyright 2007 CBAT
2007 April 10                    (CBET 918)               Daniel W. E. Green