TITLE:   GCN CIRCULAR
NUMBER:  18966
SUBJECT: GRB 160131A: GTC spectroscopy of the afterglow
DATE:    16/01/31 23:49:42 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC), 
R. Sanchez-Ramirez (IAA-CSIC), Gabriel Gomez Velarde (GRANTECAN) and
Victor Herrera (GRANTECAN) report on behalf of a larger collaboration:

We observed the afterglow of GRB 160131A (Page et al. GCN 18951) with 
the 10.4 m GTC equipped with OSIRIS. Observations consisted of 3x600s 
spectra with grism R1000B (covering from 3700 to 7800 AA) and 3x600s 
with grism R1000R (covering from 5100 to 10000 AA). The first spectrum 
started at 21:52 UT (13.53 hr after the GRB onset) under very bad seeing 
conditions (> 3").

In spite of the poor seeing we detect a strong continuum across the complete
range with multiple absorption features of FeII, NiII, MnII, MgII, MgI, and CaII 
at a common redshift of 0.972, consistent with the value measured by 
Malesani et al. from TNG (GCN 18965).

[GCN OPS NOTE(04feb16): Per author's request, GGV and VH were added 
to the author list.]