GCN Circular 15320
Subject
GRB 130831A: VLT/FORS2 spectroscopic detection of a supernova
Date
2013-10-09T09:54:39Z (11 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
S. Klose, A. Nicuesa Guelbenzu (both TLS Tautenburg), T. Kruehler (ESO),
J. Greiner, D. A. Kann, A. Rau, V. Sudilovsky (all MPE Garching), F. Olivares E. (UNAB,
MCSS, Chile), and S. Schulze (PUC, MCSS, Chile), on behalf of a larger
collaboration report:
We observed the optical transient following GRB 130831A (e.g., Hagen et
al. 2013, GCN 15139; Guidorzi et al. 2013, GCN 15140; Xu et al. 2013, GCN
15142; Yoshii et al. 2013, GCN 15143) with VLT/FORS2 equipped with the
300V grism on Sep 29 and Sep 30, 2013, between 28.5 and 29.5 days after
the burst under excellent sky conditions with mean seeing around 0.6". The
total exposure time of the spectrum was 1.53 hr and covers the spectral
range between approximately 440 and 920 nm.
In the combined spectrum, we detect the optical emission over the full
spectral range. The spectrum peaks at about 800 nm and shows broad
absorption features, very much reminiscent of the spectrum of, e.g., GRB
031203 / SN 2003lw (z=0.1055; Malesani et al. 2004, ApJ 609, L5), and the
recent GRB 120714B / SN 2012eb (z=0.40; Klose et al. 2012, GCN 13613), GRB
130215A / SN 2013ez (z=0.597; de Ugarte Postigo et al., GCN 14303), GRB
130427A / SN 2013cq (z=0.34; Xu et al. 2013, ApJ 776, 98), and GRB 130702
/ SN 2013dx (z=0.145; Schulze et al. 2013, GCN 14994), all obtained around
SN maximum light.
We conclude that we have spectroscopically discovered the appearence of a
broad-line SN following GRB 130831A at z=0.4791 (Cucchiara et al. 2013,
GCN 15144), confirming the conclusion of Pozanenko et al. (GCN 15237)
based on the optical light curve.
[GCN OPS NOTE(12oct13): Per author's request, VS was added to the author list.]