[IAUC] CBET 1775: 20090421 : SUPERNOVA 2009dn IN PGC 35993

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                                                  Electronic Telegram No. 1775
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 2009dn IN PGC 35993
     F. Yuan, University of Michigan; J. Vinko, University of Texas; R.
Quimby, California Institute of Technology; D. Chamarro, M. D. Sisson, and
C. Akerlof, University of Michigan; and J. C. Wheeler and E. Chatzopoulos,
University of Texas, on behalf of the ROTSE collaboration, report the
discovery of an apparent supernova (mag 17.5 +/- 0.2) in unfiltered CCD
images taken on Apr. 12.78 UT with the 0.45-m ROTSE-IIId telescope at the
TUBITAK National Observatory at Bakirlitepe, Turkey.  The transient was
discovered by subtracting a reference image constructed from images taken
in 2008 (limiting mag 19.2), and it was also detected with the ROTSE-IIIb
telescope at the McDonald Observatory at a similar magnitude on Apr. 11,
14, 15, and 16 (but not detected on Apr. 7.16 to a limiting magnitude of
about 18.3); the photometric uncertainties are relatively large due to
image subtraction.  The new object is located at R.A. = 11h37m39s.33,
Decl. = +46o57'11".3 (equinox 2000.0; uncertainty about 1"), which is
3".0 east and 2".5 south of the center of its apparent host galaxy,
2MASX J11373899+4657141.  Given the redshift of the presumed host (z =
0.039, measured via the Sloan Digital Sky Survey) and the observed light
curve, 2009dn is likely to be a supernova discovered around peak
brightness.  The location of 2009dn is shown in the chart posted at URL
http://rotse.net/rsvp/j113739.3+465711/j113739.3+465711.jpg.  Note that
2009dn is blended with the apparent host galaxy, due to the large pixel
scale (3".3) of ROTSE-III.
     D. W. Bishop, Rochester, NY, U.S.A., reports that J. Brimacombe (Cairns,
Australia) obtained three 600-s images of 2009dn remotely using a 51-cm
telescope in New Mexico on Apr. 20.17, showing the new star at mag 16.9 and
clearly resolved from the galaxy's nucleus.  Bishop adds that nothing is
visible at the position of 2009dn on a Digitized Sky Survey image from
a Palomar Schmidt plate taken on 1953 Mar. 10.  Brimacombe's image is
posted at website URL http://www.RochesterAstronomy.org/sn2009/p35993s1.jpg.


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                         (C) Copyright 2009 CBAT
2009 April 21                    (CBET 1775)              Daniel W. E. Green