[IAUC] CBET 1136: 20071114 : SUPERNOVA 2007qc

Mie Nov 14 02:20:21 ART 2007

                                                  Electronic Telegram No. 1136
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 2007qc
     F. Yuan, University of Michigan; R. Quimby, California Institute of
Technology; J. Aretakis and C. Akerlof, University of Michigan; and J. C.
Wheeler, University of Texas, on behalf of the ROTSE collaboration, report
the discovery of a supernova (mag 16.8) in unfiltered CCD images taken with
the 0.45-m ROTSE-IIIb telescope at McDonald Observatory on Oct. 27.49 UT.
The new object is located at R.A. = 11h57m04s.75, Decl. = +53o29'55".3
(equinox 2000.0; estimated uncertainty < 1").  There is a marginally
detected host galaxy (magnitude r = 22.9) seen at the location of the
supernova in pre-explosion SDSS imaging.  The supernova itself was observed
to be decaying at a rate of about 0.05 mag/day and was at mag 17.7 on Nov.
13.46.  The magnitudes given above are unfiltered and calibrated relative to
USNO-B1.0 R comparison-star magnitudes.  A quick reduction of the red-channel
spectra (range 510-990 nm), obtained on Nov. 13.55 by A. Rau (Caltech) with
the Palomar 5-m telescope (+ Double Beam Spectrograph), shows 2007qc to be a
type-Ia supernova at about 2 weeks past maximum light.  Using spectra of SN
1994D as a template (Patat et al. 1996, MNRAS 278, 111), an approximate
redshift of z = 0.035 is found, which would imply an absolute r magnitude
fainter than about -13 for the host galaxy.  A finding chart for 2007qc can
be found at http://www.rotse.net/transients/j1157+5329/j115705+532955.jpg.


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                         (C) Copyright 2007 CBAT
2007 November 14                 (CBET 1136)              Daniel W. E. Green