Electronic Telegram No. 2108
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 2009np
     W. Zheng and F. Yuan, University of Michigan; J. Vinko, University of
Szeged; R. Quimby, California Institute of Technology; D. Chamarro, M. D.
Sisson, N. Whallon, C. Akerlof, and S. B. Pandey, University of Michigan;
J. C. Wheeler and E. Chatzopoulos, University of Texas; and G. H. Marion
Texas A&M University and University of Texas, on behalf of the ROTSE
collaboration, report the discovery of an apparent supernova (mag about 18.0),
discovered in unfiltered images taken on 2009 Dec. 15.47 UT with the 0.45-m
ROTSE-IIIb telescope at McDonald Observatory.  The transient was monitored
for the subsequent 12 days or so, and on Dec. 27.43 its magnitude was about
17.3.  SN 2009np is located at R.A. = 12h27m06s.62, Decl. = +6o25'33".3
(equinox 2000.0; uncertainty about 1"), which is 0".04 east and 0".01 north
of the center of the host galaxy (SDSS J122706.61+062533.3; z = 0.0255).  A
finding chart for the new object can be found at the following website URL:
http://www.rotse.net/rsvp/j122706.6+062533/j122706.6+062533.jpg.  The
unfiltered light curve showed an unusual double-peaked shape with a
secondary maximum occuring on Dec. 26.
     A spectrum (range 420-1080 nm), obtained on 2010 Jan. 1.40 with the
9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J.
Caldwell, shows a blue continuum with broad features of Si II (635 nm), Fe
II (the "W" feature at 500 nm), and the Ca II infrared triplet --
characteristics of a supernova of type Ic or Ia near maximum light.  O I
(777 nm) is absent or very weak, and all the features are broader and weaker
than those in normal type-Ia supernovae.  A narrow H_alpha emission from the
host galaxy is also detected.  The GELATO code (Harutyunyan et al. 2008,
A.Ap. 488, 383; https://gelato.tng.iac.es) finds SNe 1990W (of type Ib/c, at
one day after maximum) and 2004aw (type Ic, between 1 and 9 days after
maximum) as the best-matching templates.  On the contrary, the SuperNova
IDentification code (SNID, Blondin and Tonry 2007, Ap.J. 666, 1024)
classifies 2009np as a type-Ia or type-Ic supernova with 75- and 25-percent
probability, respectively.  Despite the result by SNID, the better match
with the spectra of type-Ic supernovae and the position of 2009np within its
host galaxy (very close to the apparent center) make the type-Ic
classification more likely.  The expansion velocity, calculated from the
minimum of the Si II 635.5 nm feature, is 11000 km/s.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2010 CBAT
2010 January 4                   (CBET 2108)              Daniel W. E. Green