[vsnet-grb-info 20250] GRB 180115A: Redshift from OSIRIS/GTC

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22346
SUBJECT: GRB 180115A: Redshift from OSIRIS/GTC
DATE:    18/01/15 22:57:40 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte at iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), Z. Cano, L. Izzo, 
C.C. Thoene, D.A. Kann (HETH/IAA-CSIC), N. Castro-Rodriguez 
(Grantecan, IAC, ULL), D. Perez Valladares (Grantecan) report on 
behalf of a larger collaboration:

We observed the afterglow of GRB 180115A (Cannizzo et al. GCN 22335, 
Cano et al. GCN 22345) with OSIRIS at the 10.4m GTC telescope. The 
observation consisted of 3x900s exposure with grism R1000B, covering 
the range between 3700 and 7800 Angstrom and was performed under 
bad seeing conditions.

The observation started at 20:32 UT (16.28 hr after the burst), and the 
acquisition image shows the afterglow at r=21.2+/-0.2. The spectrum 
shows a weak continuum over all the spectral range. The low signal to 
noise ratio of the spectrum only allows us to detect a single broad spectral 
feature that we identify as Lyman alpha at a redshift of 2.487.