Electronic Telegram No. 1156
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 2007rt IN UGC 6109
     S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf
of the CfA Supernova Group, reports that a spectrogram (range 350-740 nm) of
2007rt (cf. CBET 1148), obtained by P. Berlind on Dec. 5.54 UT with the F. L.
Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-IIn
supernova around 2-3 months past maximum light.  Cross-correlation with a
library of supernova spectra using the "Supernova Identification" code (SNID;
Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2007rt is similar to
SNe 1998S and 1996L at 81 and 58 days past maximum, respectively.  The H_alpha
line (rest 656.3 nm) appears in emission only, with a narrow component of
about 2500 km/s (FWHM) superposed on a broader component of about 10000 km/s
(FWHM).  The H_beta line, on the other hand, displays a clear P-Cyg profile.
Adopting a recession velocity of 6705 km/s for the host galaxy (from The
Updated Zwicky Catalog, http://tdc-www.harvard.edu/uzc/), the maximum
absorption in the H_beta line (rest 486.1 nm) is blueshifted by roughly 9000
km/s.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2007 CBAT
2007 December 5                  (CBET 1156)              Daniel W. E. Green