Electronic Telegram No. 1776
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 2009dc IN UGC 10064
     H. Marion, University of Texas and Texas A&M University; P. Garnavich,
University of Notre Dame; and P. Challis, Harvard-Smithsonian Center for
Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that
spectra of 2009dc (cf. CBET 1762) were obtained with the NASA Infrared
Telescope Facility (+ SPEX) on Apr. 18.6 UT.  Optical spectra were also
obtained on Apr. 18 and 19 UT by M. Calkins and W. Peters with the F. L.
Whipple Observatory 1.5-m telescope (+ FAST).  The combined spectra cover
the wavelengths from 0.36 to 1.3 microns.  The presence of a strong C II
absorption at rest wavelength 658.0 nm (see CBET 1768) is confirmed, and
C II at 723.4 nm is also detected.  No absorption is seen to be associated
with the C II line at 474.5 nm, and no significant C I lines are detected
in the infrared (Marion et al. 2006, Ap.J. 645, 1392).  Unlike with SN 2006gz
(Hicken et al. 2007, Ap.J. 669, L17), the expansion velocities of Si II and
C II in 2009dc differ by only 700 km/s, and the C II equivalent width (EW) is
decreasing more slowly than in 2006gz.  Combined with the slow expansion
velocities, this suggests that SN 2009dc will be more luminous than 2006gz
and may be similar to the suspected "super-Chandra" event 2003fg (Howell et
al. 2006, Nature 443, 308).  Note, however, that SN 2009dc shows strong,
narrow Na I absorption lines from both the Galaxy (EW = 0.07 nm) and the
host (EW = 0.12 nm), implying significant dust extinction.
     Unfiltered CCD magnitudes for 2009dc:  Apr. 13.971 UT, 16.1 (J. Nicolas,
Vallauris, France, 0.28-m f/6.5 reflector); 16.013, 15.6 (E. Prosperi,
Larciano, Italy, 0.30-m f/6 Schmidt-Cassegrain reflector of Skylive Remote
Observatory, Catania).  Nicolas provides the following precise position for
2009dc:  R.A. = 15h51m12s.10, Decl. = +25o42'28".5 (equinox 2000.0).


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2009 CBAT
2009 April 22                    (CBET 1776)              Daniel W. E. Green