[IAUC] CBET 2413: 20100816 : SUPERNOVA 2010gx

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                                                  Electronic Telegram No. 2413
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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SUPERNOVA 2010gx
     A. Pastorello, S. J. Smartt, M. T. Botticella, L. Magill, D. Young,
S. Valenti, and R. Kotak, Queen's University, Belfast, on behalf of the PS1
Collaboration (see, e.g., CBETs 1617, 1988, 2214), report that a luminous
optical transient detected by three wide-field surveys has evolved into a
type-Ic supernova.  The Catalina Real Time Transient Survey first announced
the discovery of an optical transient (designated as CSS 100313:112547-084941)
at R.A. = 11h25m46s.71, Decl. = -8d49'41".4 (equinox 2000.0; cf. Mahabal
and Drake 2010, website URL http://www.astronomerstelegram.org/?read=2490 and
/?read=2508), on Mar. 13 (at SDSS r magnitude 18.6), and subsequently the
"Palomar Transient Factory" (PTF) collaboration reported an independent
discovery on images obtained during Mar. 5-16 (and designated PTF10cwr;
Quimby et al. 2010, URL http://www.astronomerstelegram.org/?read=2492).
Pastorello et al. (2010, http://www.astronomerstelegram.org/?read=2504) noted
that the transient was also detected by PS1 in the course of the 3Pi survey
during Mar. 12-23 (which they designated PS1-1000037).  Early spectra by the
CRTS, PTF, and PS1 teams all indicated a blue continuum with broad O II
features and a host-galaxy (SDSS J112546.72-084942.0) redshift of z = 0.23.
The host redshift implies a very luminous transient (absolute mag < -21),
and the spectra were similar to the "ultra-bright" supernova 2005ap (see
http://www.astronomerstelegram.org/?read=2490, /?read=2508, /?read=2492,
/?read=2504; also, Quimby et al. 2007, Ap.J. 668, L99).  Further detailed
spectroscopic monitoring with the Gemini South telescope and the William
Herschel Telescope by the PS1 team shows that -- 25 days after discovery --
the transient (here designated supernova 2010gx) evolved unambiguously into
a type-Ic event with the characteristic broad Fe II, Si II, Mg II, and Ca II
features.  The spectra at +25 days are most similar to those of SN 1994I
(at six days before peak; Baron et al. 1996, MNRAS 279, 799) and SN 2003jd
(at peak; Valenti et al. 2008, MNRAS 383, 1485).  This indicates a link
between the "ultra-bright" optical transients and type-Ic supernovae;
further details are reported by Pastorello et al. (2010, Ap.J., submitted).


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                         (C) Copyright 2010 CBAT
2010 August 16                   (CBET 2413)              Daniel W. E. Green