[vsnet-grb-info 15910] GRB 141220A: Redshift from OSIRIS at the 10.4m GTC

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17198
SUBJECT: GRB 141220A: Redshift from OSIRIS at the 10.4m GTC
DATE:    14/12/20 07:53:28 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte at iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC),
J. Gorosabel (UPV, IAA-CSIC), N. Tanvir (U. Leicester), J.P.U. Fynbo (DARK/NBI),
P. Pesev (GRANTECAN), G. Gomez Velarde (GRANTECAN), and 
D. Perez Valladares (GRANTECAN) report on behalf of a larger collaboration

We observed the afterglow of GRB141220A (Cummings et al. GCN 17196, Gorosabel
et al. GCN 17197) with OSIRIS at the 10.4m GTC. Observations began at 6:45 UT 
(50 min after the burst). In a first 600 s spectrum obtained with grism R1000B covering 
from 3750 to 7800 A we detect absorption features of AlII, FeII, MgII, MgI, at a redshift 
of 1.3195, including several absorptions of FeII* which make it very likely the redshift of 
the GRB. We also detect two MgII intervening systems at redshifts of 1.280 and 0.527.