GCN Circular 21359
Subject
GRB 170714A: Bastille Day Burst redshift from OSIRIS/GTC
Date
2017-07-21T06:36:26Z (7 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D.A. Kann,
L. Izzo, C.C. Thoene (HETH/IAA-CSIC), G. Lombardi S. Geier
(GTC, IAC-ULL), A. Garcia, A. Perez (GTC) report:
Following the detection of the afterglow (de Ugarte Postigo et al. GCN
21346) of the ultra-long GRB 170714A (D'Ai et al. GCN 21340, Kann
et al. GCN 21345) we obtained further NIR and optical observations on
19 and 20 of July, with detections in r, i, z, and H-bands. An object is
still observed at the position earlier reported, indicating an important
host galaxy contribution.
On 21 July, at 4:53 UT (5.69 days after the burst) we obtained
spectroscopy of the afterglow/host galaxy with OSIRIS at the 10.4m
GTC telescope (La Palma, Spain). Observations consisted of 4x900 s
with grism R1000R, covering the range between 5100 and 10000 AA.
The combined spectrum shows a weak trace with several
superimposed emission lines, which we interpret as due to [OII], [OIII]
and H-beta, through which we derive a redshift for the host galaxy,
and hence for GRB 170714A, of 0.793.