[vsnet-grb-info 12104] VLT/FORS2 redshift of GRB120716A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13493
SUBJECT: VLT/FORS2 redshift of GRB120716A
DATE:    12/07/19 08:40:51 GMT
FROM:    Arne Rau at MPE  <arau at mpe.mpg.de>

Jochen Greiner, Arne Rau, Patricia Schady (all MPE), Ivo Saviane (ESO), 
and Brad Cenko ( UC Berkeley) report on behalf of a larger collaboration.

We observed the afterglow candidate of GRB 120716A (Hurley et al., GCN 
13454; Cenko et al. GCN 13489; Xu et al, GCN 13490; Schady et al. CGN 
13492) with the ESO VLT equipped with the FORS2 spectrograph. 
Observations with the 600B grism, covering a spectral range of 
350-610nm) started at ~06:54 UT on July 19th 2012 (~58.2 hr after the 
gamma-ray trigger) and lasted for ~ 1.5hr.

The spectrum shows a prominent, broad absorption trough centered at 
~4250A, interpreted as Lyman-alpha, together with numerous metal lines 
(SiII, OI, SiIV, CIV) at longer wavelength. We find a common redshift of 
these features of z=2.48.