Electronic Telegram No. 2245
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2010br IN NGC 4051
     Vitali Nevski, Vitebsk, Belarus, reports the discovery of a possible
supernova (mag approximately 17.7) on ten unfiltered 180-s CCD images
(limiting mag 20.0) taken on Apr. 10.88 UT with a 0.3-m reflector + CCD.
The new object, which appeared at mag approximately 17.5 on Apr. 11.81, is
located at R.A. = 12h03m10s.95, Decl. +44o31'43".1 (equinox 2000.0), which
is about 19".5 east and 10" south of the center of the galaxy NGC 4051.
Nothing is visible at this position on a Palomar Sky Survey red plate
obtained on 1996 Mar. 17 or a blue plate obtained on 1990 Jan. 29 (via the
Digitized Sky Survey; limiting mag 21.5).  The discovery images are posted
at the following website URLs: http://tinyurl.com/y2f8mwv and
http://tinyurl.com/y5h3rfb.  Following posting on the Central Bureau's
unconfirmed-objects webpage, A. Maksym (Terskol, Russia) writes that he
imaged 2010br with a 0.6-m reflector on Apr. 11.819, yielding magnitude
R = 17.9 and position end figures 10s.90, 43".3 (UCAC2 catalogue).  Maksym
has posted his image at URL http://tinyurl.com/y83bq2s.  Also, L. Elenin
(Lyubertsy, Russia) and M. Schwartz (Rio Rico, Arizona, USA) report that
2010br appears at mag R = 17.1 and V = 17.7 on a CCD image obtained on Apr.
13.435 by Schwartz with a 0.81-m telescope at the Tenagra II Observatory
and measured by Elenin, who provides position end figures 10s.93, 43".6;
2010btr is not visible on Digitized Sky Survey images (no dates, bandpasses,
or limiting magnitudes provided).
     A. J. Maxwell, M. L. Graham, A. Parker, S. Sadavoy, and C. J. Pritchet,
Department of Physics and Astronomy, University of Victoria; E. Y. Hsiao,
Lawrence Berkeley Laboratory; and D. D. Balam, Dominion Astrophysical
Observatory, National Research Council of Canada, report that a noisy
spectrogram (range 390-703 nm, resolution 0.3 nm) of 2010br, obtained on
Apr. 14.25 with the 1.82-m Plaskett Telescope of the National Research
Council of Canada, shows the spectrum to be similar to that of a type-Ib/c
supernova.  Comparison with a library of supernova spectra using the
"superfit" matching program of Howell et al. (2005, Ap.J. 634, 1190)
indicates that 2010br is similar to the type-Ib/c supernova 1987K.  Balam
reports that his CCD image taken on Apr. 15.21 yields position end figures
10s.96, 42".8 (offset 14".3 east, 9".7 south of the core of NGC 4051) and
magnitude R = 18.3 +/- 0.1.


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

                         (C) Copyright 2010 CBAT
2010 April 16                    (CBET 2245)              Michael Rudenko