[vsnet-grb-info 17552] The bright GRB160203A: X-shooter spectroscopy and redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18982
SUBJECT: The bright GRB160203A: X-shooter spectroscopy and redshift 
DATE:    16/02/03 04:22:29 GMT
FROM:    Giovanna Pugliese at API/UvA  <pugliese at astroduo.org>

G. Pugliese (API/UvA), S. Covino (INAF/OAB), T. Kruehler (MPE Garching), D. Xu (NAOC/CAS), 
N. R. Tanvir (Leicester), report on behalf of a larger collaboration:

We observed the afterglow of GRB 160203A (D'Avanzo et al., GCN 18979;
Kruehler et al., GCN 18980; Xu, GCN 18981) with ESO's Very Large
Telescope UT2 equipped with X-shooter. Our observations were performed
in Rapid Response Mode and started at 02:31:35 UT on 03-02-2016, just about 
18 min after the Swift trigger. The X-shooter spectra cover the range between 
3000 and 23000 AA, and were obtained at a seeing of around 0.8".

A preliminary analysis of the spectrum shows a clear continuum with
absorption features due to Lyman-alpha and various metal lines (SII 1254, SiII 1259/60, OI 1302, 
SiII 1304, CII 1334, Si IV 1393/1402, SiII 1526, CIV 1548/1550, FeII 1608, AlII 1670) at a common 
redshift of 3.52, which we propose as the redshift of the GRB. 
We also detect an intervening system at z=2.203.

We acknowledge the fast and efficient support provided by Paranal staff. In particular we thank Dimitri 
Gadotti, Boris Haeussler, and Marcela Espinoza for their excellent job.