{
  "bibcode": "2018GCN.23315....1V",
  "body": "J-B. Vielfaure (CNRS - GEPI/Observatorie de Paris), J. Japelj (API, U.\nAmsterdam), D. B. Malesani (DAWN/NBI and DARK/NBI), V. D'Elia (SSDC), J. P.\nU. Fynbo (DAWN/NBI), N. R. Tanvir (Univ. Leicester), S. D. Vergani (CNRS -\nGEPI/Observatorie de Paris), A. Rossi (INAF-OAS), P. Vreeswijk (Radboud\nUniv. Nijmegen), L. Izzo (HETH/IAA-CSIC), D. A. Kann (HETH/IAA-CSIC), B.\nMilvang-Jensen (DAWN/NBI), D. Xu (NAOC) and K. E. Heintz (Univ. of\nIceland), report on behalf of the Stargate collaboration:\n\nWe observed the optical counterpart of GRB 181010A (Melandri et al. GCN\n23309; E. Gorbovskoy et al. 23310; R. Martone et al. 23311; E. Troja et al.\n23312) with the ESO-VLT UT2 equipped with the X-shooter spectrograph. From\nthe acquisition image we measure a preliminary magnitude of 20.4 +/- 0.1\nmag in the r-band, calibrated against local Pan-STARRS sources. Several\nspectra with increasing exposure time were collected; in this analysis we\nconsider only one with 600s exposure obtained in a Rapid Response Mode at\n06:18:24.9 UT (at the start of observation, 0.37 hr after the GRB).\n\nA bright continuum is observed across the entire wavelength range covered\nby X-shooter. Several absorption and emission features are detected, which\ncan be identified as due to H-alpha and [OIII]5007/4959 in emission at z =\n1.39. At this same redshift we also detect AlII1854/1862, SiII1808, the\nMgII doublet, and MgI in absorption. Fine-structure lines from FeII and\nNiII are also detected at z = 1.39, which makes the redshift association\nwith the GRB secure. An intervening system at z = 0.67 with absorption\nfeatures due to the MgII doublet and MgI is also identified in the\nspectrum.\n\nWe acknowledge the ESO observing staff at Paranal, in particular Jorge\nLillo-Box.",
  "circularId": 23315,
  "createdOn": 1539172143000,
  "email": "jean.baptiste.vielfaure@gmail.com",
  "subject": "GRB 181010A: VLT/X-shooter redshift",
  "submitter": "Jean Baptiste at Paris Observatory  <jean.baptiste.vielfaure@gmail.com>",
  "eventId": "GRB 181010A"
}