[IAUC] CBET 1492: 20080903 : SUPERNOVA 2008fh

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                                                  Electronic Telegram No. 1492
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 2008fh
     Further to CBET 1481, J. Leja, D. Winslow, W. Li, and A. V. Filippenko,
University of California, report the LOSS discovery of a variable object
on unfiltered KAIT images:

 SN       2008 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2008fh   Aug. 30.50   3 20 18.64  +41 21 44.0   19.7    73".6 E, 16".4 S

Additional KAIT magnitudes for 2008fh:  a combined unfiltered image from
2007 Oct.-Dec., [21.2; 2008 Aug. 31.51 UT, 19.8.  The variable source is
in Abell cluster 426 but is not obviously associated with any specific
member galaxy of the cluster.  The offset above is measured relative to
NGC 1282.  A finder chart for the new object is availble at the following
website URL:  http://astro.berkeley.edu/~bait/2008/sn2008-n1282.gif.
     Following posting on the Central Bureau's unconfirmed-objects webpage,
D. D. Balam (Dept. of Physics and Astronomy, University of Victoria) reports
that images obtained with the 1.82-m Plaskett telescope (+ SDSS filters) of
the National Research Council of Canada on Sept. 2.34 UT yields position end
figures 18s.68, 44".3 for 2008fh and the following magnitudes:  g = 20.93
(0.06), g-r = +0.67 (0.11).
     An independent discovery of 2008fh has been reported by F. Yuan,
University of Michigan; R. Quimby, California Institute of Technology; D.
Chamarro, A. Uecker, M. D. Sisson, and C. Akerlof, University of Michigan;
and J. C. Wheeler, University of Texas, on behalf of the ROTSE collaboration,
from unfiltered CCD images taken on July 30.36 (showing 2008fh at mag about
18.3), Aug. 1.34 (mag about 18.0), and 9.33 UT (mag about 18.8) with the 0.45-m
ROTSE-IIIb telescope at McDonald Observatory, providing position end figures
18s.59, 45".1.  Nothing was detected to mag about 18.7 on an image takein on
July 24.38.  There is no apparent host seen in the Digitized Sky Survey
image, but the location is in the middle of a group of galaxies in the
Perseus cluster.  A ROTSE finding chart of 2008fh can be found at URL
http://www.rotse.net/rsvp/j032018.6+412145/j032018.6+412145.jpg.  Spectra
(range 420-890 nm) of 2008fh -- obtained under poor conditions on Aug. 21.37
by M. Shetrone and A. Westfall, and under improved conditions on Aug. 26.37
by J. Caldwell and V. Riley, with the 9.2-m Hobby-Eberly Telescope (+
Marcario Low-Resolution Spectrograph) -- show broad (FWHM about 10000 km/s)
emission features similar to those in spectra of type-Ia supernovae in the
nebular phase.  The best-fit match from SNID (Blondin and Tonry 2007, Ap.J.
666, 1024), is to spectra of SN 1991bg arround 30 days past maximum light;
however, the fit is imperfect and results in a formal redshift estimate of
z = 0.008 +/- 0.008.  By eye, the data longward of 630 nm are similar to
those of 1991bg around 50 days past maximum, but with a much stronger
emission peak at about 870 nm (observed).  From this fit, a redshift of
approximately z = 0.01 is estimated.  If the object is in the Perseus
galaxy cluster (Abell 426), then -- correcting for Galactic extinction --
the peak absolute magnitude would correspond to about -16.7, which would
be consistent with a subluminous, 1991bg-like supernova at this distance
(z = 0.0179, Struble and Rood 1999, Ap.J. Suppl. 125, 35).


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                         (C) Copyright 2008 CBAT
2008 September 3                 (CBET 1492)              Daniel W. E. Green