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GCN Circular 17198

GRB 141220A: Redshift from OSIRIS at the 10.4m GTC
2014-12-20T07:53:28Z (9 years ago)
Antonio de Ugarte Postigo at IAA-CSIC <>
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.
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