[vsnet-grb-info 14093] GRB 131030A: NOT redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15407
SUBJECT: GRB 131030A: NOT redshift
DATE:    13/10/30 22:48:32 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark at gmail.com>

D. Xu, J. P. U. Fynbo (DARK/NBI), P. Jakobsson, Z. Cano (U. Iceland),
B. Milvang-Jensen, D. Malesani (DARK/NBI), A. de Ugarte Postigo
(IAA-CSIC, DARK/NBI) & M. Hayes (Stockholm University) report on
behalf of a larger collaboration:

We observed the optical afterglow of GRB 131030A (Troja et al., GCN
15402) with the NOT equipped with the AlFOSC instrument. The transient
is clearly detected in our acquisition image with a magnitude R ~ 17
at a mean time of 0.569 hr after the GRB.

A single spectrum of 1200 s covering the range from 3800 to 8000 AA
was obtained with a mean epoch of 0.894 hr after the burst. The
spectrum displays a strong continuum with features of Fe II, Mg II and
Al II at a common redshift of z = 1.293 (wavelength calibration based
on archival data), which we identify as the redshift of the GRB. We
also detect an intervening system at z = 1.16 displaying Fe II and Mg
II.