Electronic Telegram No. 926
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 2007J IN UGC 1778
     A. V. Filippenko, R. J. Foley, J. M. Silverman, R. Chornock, and W.
Li, University of California, Berkeley; S. Blondin, Harvard-Smithsonian
Center for Astrophysics; and T. Matheson, National Optical Astronomy
Observatory, report that high-quality CCD spectra (range 320-920 nm)
of SN 2007J (IAUC 8798), obtained on Jan. 21, Feb. 14, and Mar. 18
with the Keck I 10-m telescope (+ LRIS), show that 2007J is not a
peculiar type-Ia supernova as reported on CBET 817, but rather a
peculiar type-Ib supernova.  Strong He I emission lines are present in
the Feb. 14 spectrum; they are especially prominent in the Mar. 18
spectrum and have a full-width-at-half-maximum intensity of about 4000
km/s.  The presence of He I emission lines makes the spectrum resemble,
to some extent, that of the peculiar type-Ib supernova 2006jc (Foley et
al. 2007, Ap.J. 657, L105) at about 2 months past maximum brightness,
although in SN 2007J there are no very broad lines and the continuum
shape is different.  H-alpha absorption appears to be present in the
Jan. 14 spectrum, similar to that observed in type-IIb supernovae (e.g.,
Filippenko 1997, ARAA 35, 309); the derived blueshift of the absorption
minimum is about 2900 km/s.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2007 CBAT
2007 April 17                    (CBET 926)               Daniel W. E. Green