[vsnet-grb-info 19046] GRB 170202A VLT/X-shooter redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20589
SUBJECT: GRB 170202A VLT/X-shooter redshift
DATE:    17/02/03 09:49:18 GMT
FROM:    Jesse Palmerio at IAP  <palmerio at iap.fr>

J. Palmerio (Univ. Paris VI, IAP), T. Kruehler (MPE Garching), D.
Malesani, J. P. U. Fynbo (DARK/NBI) report on behalf of a larger
collaboration:

We observed the optical afterglow of GRB 170202A
(Racusin et al. GCN 20575) with the ESO
Very Large Telescope UT 2 (Kueyen) equipped with the X-shooter
spectrograph, covering the wavelength range 3500-20000 AA.
Spectroscopy started at 04:10:05 UT on 2017-02-03 (i.e., 9.7 hr after the
GRB)
 and consisted of 4 exposures of 600 s each.

The spectrum exhibits several absorption features such as Lya, CIV,
SiIV, FeII, SiII, MgII as well as the [OIII]5007 emission line,
 all at a common redshift of z=3.645, consistent with
A. de Ugarte Postigo et al. (GCN 20584) and D. Xu et al. (GCN 20588).
We conclude this is the redshift of the GRB.

We acknowledge the excellent support from the ESO staff, particularly
Fernando J. Selman, A. Mehner in obtaining these observations.