[IAUC] CBET 1174: 20071220 : SUPERNOVA 2007sr IN NGC 4038

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                                                  Electronic Telegram No. 1174
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 2007sr IN NGC 4038
     G. Umbriaco, T. Pietrogrande, and F. Di Mille, Dipartimento di Astronomia,
Universita' di Padova; and I. Agnoletto, A. Harutyunyan, and S. Benetti,
Istituto Nazionale di Astrofisica and Osservatorio Astronomico di Padova,
report that a spectrogram (range 335-770 nm, resolution 0.9 nm) of 2007sr (cf.
CBET 1172, 1173), obtained on Dec. 20.22 UT at Asiago with the Galileo 1.22-m
telescope (+ Boller & Chivens spectrograph), shows it to be a type-Ia
supernova.  Assuming a recession velocity of 1642 km/s (Lauberts and Valentijn
1989, The Surface Photometry Catalogue of the ESO-Uppsala Galaxies; via NED)
for the host galaxy, the 'PASSparToo' spectrum-comparison code (Harutyunyan et
al. 2005, ASP Conf. Ser. 342, 258) provides good fits to spectra of SNe 1996Z
and 2002bo at five and four days after B-maximum light, respectively.  The
phase is confirmed by the high expansion velocity deduced from the Si II
635.5-nm absorption feature (about 12100 km/s) shown by the HVG class (Benetti
et al. 2005, Ap.J. 623, 1011) during the photospheric phases.
     Visual magnitude estimate by P. Schmeer, Bischmisheim, Germany:
Dec. 20.249 UT, 12.8.


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                         (C) Copyright 2007 CBAT
2007 December 20                 (CBET 1174)              Daniel W. E. Green