Skip to main content
New Swift-BAT/GUANO and IceCube Notice Types Available! See news and announcements

GCN Circular 23315

GRB 181010A: VLT/X-shooter redshift
2018-10-10T11:49:03Z (5 years ago)
Jean Baptiste at Paris Observatory <>
J-B. Vielfaure (CNRS - GEPI/Observatorie de Paris), J. Japelj (API, U.
Amsterdam), D. B. Malesani (DAWN/NBI and DARK/NBI), V. D'Elia (SSDC), J. P.
U. Fynbo (DAWN/NBI), N. R. Tanvir (Univ. Leicester), S. D. Vergani (CNRS -
GEPI/Observatorie de Paris), A. Rossi (INAF-OAS), P. Vreeswijk (Radboud
Univ. Nijmegen), L. Izzo (HETH/IAA-CSIC), D. A. Kann (HETH/IAA-CSIC), B.
Milvang-Jensen (DAWN/NBI), D. Xu (NAOC) and K. E. Heintz (Univ. of
Iceland), report on behalf of the Stargate collaboration:

We observed the optical counterpart of GRB 181010A (Melandri et al. GCN
23309; E. Gorbovskoy et al. 23310; R. Martone et al. 23311; E. Troja et al.
23312) with the ESO-VLT UT2 equipped with the X-shooter spectrograph. From
the acquisition image we measure a preliminary magnitude of 20.4 +/- 0.1
mag in the r-band, calibrated against local Pan-STARRS sources. Several
spectra with increasing exposure time were collected; in this analysis we
consider only one with 600s exposure obtained in a Rapid Response Mode at
06:18:24.9 UT (at the start of observation, 0.37 hr after the GRB).

A bright continuum is observed across the entire wavelength range covered
by X-shooter. Several absorption and emission features are detected, which
can be identified as due to H-alpha and [OIII]5007/4959 in emission at z =
1.39. At this same redshift we also detect AlII1854/1862, SiII1808, the
MgII doublet, and MgI in absorption. Fine-structure lines from FeII and
NiII are also detected at z = 1.39, which makes the redshift association
with the GRB secure. An intervening system at z = 0.67 with absorption
features due to the MgII doublet and MgI is also identified in the

We acknowledge the ESO observing staff at Paranal, in particular Jorge
Looking for U.S. government information and services? Visit