[IAUC] CBET 3637: 20130826 : SUPERNOVA 2013ez = GRB 130215A

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                                                  Electronic Telegram No. 3637
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.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2013ez = GRB 130215A
     A. de Ugarte Postigo, Instituto de Astrofisica de Andalucia (IAA),
Consejo Superior de Investigaciones Cientificas (CSIC), and Dark Cosmology
Centre, Niels Bohr Institute, University of Copenhagen; Z. Cano, University
of Iceland; C. C. Thoene, IAA/CSIC; J. Gorosabel, IAA/CSIC and University of
the Basque Country; R. Sanchez-Ramirez, IAA/CSIC; G. Leloudas, Oskar Klein
Centre, Stockholm University, and Dark Cosmology Centre; D. Xu, Dark
Cosmology Centre; K. Wiersema, University of Leicester; J. P. U. Fynbo, D.
Malesani, and J. Hjorth, Dark Cosmology Centre; P. Jakobsson, University of
Iceland; and O. E. Hartoog, University of Amsterdam, on behalf of a larger
collaboration, report that they have been monitoring the optical counterpart
of GRB 130215A (discovered with the Swift satellite on Feb. 15.064 UT; cf.
D'Elia et al., posted at URL http://gcn.gsfc.nasa.gov/gcn3/14204.gcn3, GCN
Circular 14204, citing position R.A. = 2h53m55s, Decl. = +13d22'14", equinox
2000.0, uncertainty 3'; also, Zheng et al., GCN Circ. 14205, at position end
figures 54m00s.7, 23'43".7, and unfiltered CCD mag 14.2 on Feb. 15.072). The
present authors obtained spectroscopy of the optical counterpart with the
10.4-m Gran Telescopio Canarias (GTC) at Roque de los Muchachos Observatory
in La Palma, Spain, around Mar. 12.87, at 25.8 days after the onset of the
gamma-ray burst, which is 16.2 days after the burst in the host-galaxy rest
frame (z = 0.597; cf. Cucchiara et al., GCN Circ. 14207).  Observations
consisted of three 1200-s exposures with the R500R grism, covering the range
480-1000 nm, with a resolution of about 600.  Due to the variable's low
altitude at the time of the observations, the data had to be obtained at high
airmass (between 1.6 and 2.2), and there were thin cirrus clouds, but the
seeing was very good (0".6).  At this epoch, the spectrum presents undulations
typical of supernovae spectra, including a prominent bump at about 850 nm.
The spectrum has been compared to a series of supernovae templates using SNID
version 5.0 (Blondin and Tonry 2007, Ap.J. 666, 1024), and a good match is
obtained when compared to a number of type-Ic supernovae, including broad-
lined and normal events such as SN 2002ap and SN 1994I around maximum light
and up to +10 days.  When leaving the redshift unconstrained, the fit returns
a value of z = 0.60 +/- 0.02, fully consistent with that obtained from
absorption-line spectroscopy.  A comparison of the spectrum of GRB 130215A
with that of SN 2002ap has been posted by the authors at the following URL:
http://www.iaa.es/~deugarte/GRBs/130215A/130215A.jpg.


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                         (C) Copyright 2013 CBAT
2013 August 26                   (CBET 3637)              Daniel W. E. Green