Electronic Telegram No. 967
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)
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SUPERNOVA 2007ci IN NGC 3873
     S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics report that a spectrogram (range 350-740 nm) of
2007ci (cf. CBET 966), obtained by M. Calkins on May 18.21 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 2007ci is most similar to the subluminous
type-Ia supernova 2005am (cf. IAUC 8491) at maximum, characterized by a
strong absorption feature at 580 nm due to Si II.  Adopting a recession
velocity of 5405 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 12500 km/s.  Assuming that the
galaxy is in the Hubble flow and the supernova suffers negligible extinction,
the discovery magnitude of 17.5 corresponds to an absolute magnitude of
roughly -16.9, which confirms the subluminous nature of the event.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2007 CBAT
2007 May 19                      (CBET 967)               Daniel W. E. Green