GCN Circular 26998
Subject
GRB 200205B: VLT/X-shooter redshift
Date
2020-02-06T03:17:38Z (4 years ago)
From
Daniele B Malesani at DTU Space <malesani@space.dtu.dk>
J.-B. Vielfaure (GEPI - Paris Observatory), D. Xu (NAO/CAS), J. Palmerio
(GEPI - Paris Observatory), D. B. Malesani (DTU Space), L. Izzo
(DARK/NBI), D. A. Kann (HETH/IAA-CSIC), A. J. Levan (Radboud Univ.), G.
Pugliese (Univ. Amsterdam), N. R. Tanvir (Univ. Leicester) report on
behalf of the Stargate collabaration:
We observed the optical afterglow of GRB 200205B (Evans et al., GCN
26993) using the ESO VLT UT2 (Kueyen) equipped with the X-shooter
spectrograph. Our spectra cover the wavelength range 3000-25000 AA, and
consist of 4 exposures by 600 s each. The observation mid time was 2020
Feb 6.063 UT (6.16 hr after the GRB).
In a 30 s image taken with the acquisition camera on Feb 6.041 UT, we
detect the optical afterglow, for which we measure a magnitude r = 20.34
+- 0.03 AB (calibrated against nearby stars from the SkyMapper catalog;
Wolf et al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574).
We clearly detect continuum over the wavelength range 3100-24000 AA.
From detection of multiple absorption features, which we interpret as
due to C ii, Si iv, Si ii, C iv, Fe ii, Al ii, Mg ii, we infer a
redshift z = 1.465.
Emission lines are also detected, which we interpret as due to the [O
ii] and [O iii] doublets, Hbeta, and Halpha, all at the above quoted
redshift.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular J. Corral-Santana and J. Velasquez.