[vsnet-grb-info 20388] GRB 180314A: VLT/X-shooter redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22484
SUBJECT: GRB 180314A: VLT/X-shooter redshift
DATE:    18/03/14 12:27:27 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

B. Sbarufatti (INAF/Brera PSU), J. Bolmer (MPE), A. De Ugarte Postigo 
(IAA/CSIC and DARK/NBI), J. P. U. Fynbo (DAWN/NBI), J. Selsing 
(DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), D. Malesani 
(DAWN/NBI and DARK/NBI), N. R. Tanvir (Univ. Leicester), A. J. Levan 
(Univ. Warwick), A. Smette (ESO), K. Wiersema (Univ. Warwick), S. Covino 
(INAF/Brera), report on behalf of the Stargate collaboration:

We observed the optical counterpart of GRB 180314A (D'Avanzo et al., GCN 
22478; Bolmer, GCN 22479) with the ESO/VLT UT2 equipped with the 
X-shooter spectrograph. Observations started on Mar 14.067 UT (53.3 min 
after the GRB) and covered the wavelength range 3000-20000 AA. In our 
acquisition image, we measure for the afterglow r = 18.87 +- 0.05 AB, 
calibrated to the Pan-STARRS catalog. The afterglow position is RA = 
06:37:03.66, Dec = -24:29:46.2, consistent with the UVOT position 
(D'Avanzo et al., GCN 22478).

A high-S/N continuum is detected in all arms (reaching ~3100 AA in the 
blue end). We identify several absorption features, including Mg II, Zn 
II, Al II, Al III, Cr II, Fe II at a common redshift z = 1.445. We also 
detect at least one Fe II* fine-structure line at the same redshift, 
thus confirming the association of this system with GRB 180314A.

We acknowledge excellent support from the observing staff in Paranal, in 
particular Boris Haeussler and Zahed Wahhaj.