[IAUC] CBET 4196: 20151123 : SUPERNOVA 2011kl = GRB 111209A

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                                                  Electronic Telegram No. 4196
Central Bureau for Astronomical Telegrams
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SUPERNOVA 2011kl = GRB 111209A
     Jochen Greiner, Max Planck Institut fuer Extraterrestrische Physik,
Garching; Paolo Mazzali, Astrophysics Research Institute, Liverpool, and
Max Planck Institut fuer Astrophysik, Garching; D. Alexander Kann and Sylvio
Klose, Thueringer Landessternwarte, Tautenburg; Thomas Kruehler, European
Southern Observatory, Santiago; and Elena Pian, Istituto Nazionale di
Astrofisica, Bologna, and Scuola Normale Superiore, Pisa, report (on behalf
of a larger collaboration) that monitoring of the fading afterglow of GRB
111209A at z = 0.677 (Vreeswijk et al. 2011, GCN Circ. 12648; viewable at
website URL http://gcn.gsfc.nasa.gov/gcn3/12648.gcn3) and position R.A. =
0h57m22s.64, Decl. = -46d48'03".6 (equinox J2000.0; 0".3 uncertainty) with
the Gamma-Ray Burst Optical Near-Infrared Detector (GROND, a 7-channel
imager mounted at the 2.2-m MPG telescope at La Silla; cf. Greiner et al.
2008, PASP 120, 405) has revealed a clear re-brightening between about 15-30
days after the gamma-ray burst (GRB) detection.  At the given redshift, this
is a factor of three more luminous than the brightest known GRB-related
supernova.  A VLT/X-shooter spectrogram taken on 2011 Dec. 29, near the peak
of the excess emission, is more similar in shape to those of superluminous
supernovae (Quimby et al. 2011, Nature 474, 487) than those of GRB supernovae,
rising towards the ultraviolet down to 300 nm rest-frame.  The combination of
large luminosity and low metal-line opacity makes it impossible to classify
the supernova of GRB 111209A, designated SN 2011kl, as a canonical broadlined
type-Ic supernova.  The lightcurve and the spectrum of 2011kl can be
reproduced by a model involving extra energy injected by a magnetar (full
details given by Greiner et al. 2015, Nature 523, 189; posted at website URL
http://www.nature.com/nature/journal/v523/n7559/full/nature14579.html).


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                         (C) Copyright 2015 CBAT
2015 November 23                 (CBET 4196)              Daniel W. E. Green