[IAUC] CBET 2476: 20101002 : SUPERNOVA 2010hy

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                                                  Electronic Telegram No. 2476
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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SUPERNOVA 2010hy
     J. Vinko, University of Szeged; J. C. Wheeler and E. Chatzopoulos,
University of Texas; and G. H. Marion, Harvard-Smithsonian Center for
Astrophysics and University of Texas, report that a spectrogram, obtained on
Sept. 30.15 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-
Resolution Spectrograph) by J. Caldwell, confirms the previous finding by
Cenko et al. (CBET 2461) that 2010hy is a type-Ic supernova.  SNID (Blondin
and Tonry 2007, Ap.J. 666, 1024) indicates that the spectrum of 2010hy is
most similar to those of SN 2004aw within a few days of maximum light.  The
features of Mg II at 448.1 nm, the Fe II "W" feature around 500 nm, and Si II
635.5-nm can be unambigously identified.  O I at 777.4 nm and the Ca II near-
infrared triplet may be present but heavily contaminated by telluric lines
and buried by noise.  The average redshift from these supernova features is
z = 0.19.  Because SN 2010hy presumably brightened since its discovery before
maximum (Sept. 4 at unfiltered CCD mag 19.1), this redshift value indicates a
peak absolute magnitude brighter than -20.4.  SN 2010hy is very probably an
overluminous event, similar to SN 2007bi, which was suggested as a possible
pair-instability supernova explosion (Gal-Yam et al. 2009, Nature 462, 624).


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                         (C) Copyright 2010 CBAT
2010 October 2                   (CBET 2476)              Daniel W. E. Green