[IAUC] CBET 1112: 20071102 : SUPERNOVA 2007ob

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                                                  Electronic Telegram No. 1112
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 2007ob
     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 on unfiltered CCD images obtained with the
0.45-m ROTSE-IIIb telescope at McDonald Observatory on Oct. 28.13 (at mag
about 17; poor seeing) and 30.23 UT (mag about 17.5); the new object was
found by subtracting a co-addition of images taken between July 15 and Aug.
16 (limiting mag about 19.6).  SN 2007ob is located at R.A. = 23h12m25s.99,
Decl. = +13o54'49".3 (equinox 2000; uncertainty < 1"), which is 0".1 east
and 0".7 south of the center of the apparent host galaxy.  A finding chart
can be found at URL http://www.rotse.net/transients/j2312+1355/index.html.
A spectrum (range 420-890 nm) was obtained on Nov. 1.22 with the 9.2-m
Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J.
Caldwell, V. Riley, and E. Terrazas, and though the data are heavily
contaminated by galaxy light, several broad features indicative of a type-Ia
supernova are detected:  Specifically, an absorption trough is observed
around 630 nm, which is identified as Si II 635.5-nm; correcting for the
recession velocity using the host-galaxy redshift from the SDSS, the
expansion velocity derived from the minimum of this Si II feature is about
12000 km/s.


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                         (C) Copyright 2007 CBAT
2007 November 2                  (CBET 1112)              Daniel W. E. Green