{
  "bibcode": "2015GCN.18187....1D",
  "body": "V. D'Elia (ASI/ASDC and INAF-OAR), T. Kruehler (ESO), K. Wiersema (U. \nLeicester), N. R. Tanvir (U. Leicester), J. Japelj (U. Ljubljana), G. \nPugliese (API/UvA), D. Malesani (DARK/NBI), B. Milvang-Jensen \n(DARK/NBI), J. P. U. Fynbo (DARK/NBI), report on behalf of a larger \ncollaboration:\n\nWe observed the optical counterpart of GRB 150821A (Troja et al., GCN \n18186) with the ESO VLT equipped with the X-shooter spectrograph. Four \nspectra with individual exposure time of 600 s were secured covering the \nwavelength range 3,000-25,000 AA. Observations were carried out in \nrobotic \"rapid response mode\" (RRM) and spectroscopy began 12.4 min \nafter the BAT trigger (7.7 min after the XRT position, at which point \nthe VLT was triggered). The afterglow is well detected in our \nacquisition image, with a magnitude of R ~ 16 (11.1 min after the GRB), \ncalibrated to one nearby USNO star.\n\nWe detect a number of absorption features at a common redshift of z = \n0.755, including Mg II, Mg I, Fe II, Zn II. We also detect \nfine-structure lines at the same redshift (e.g. FeII* 2396 / 2389, and \nNi II** 2166 / 2217 / 2223), confirming that the absorption system is \nlocal to the GRB and not intervening.\n\nWe thank the kind assistence of the observing staff at Paranal, in \nparticular Claudia Cid and Marcela Espinoza.",
  "circularId": 18187,
  "createdOn": 1440156604000,
  "email": "malesani@dark-cosmology.dk",
  "subject": "GRB 150821A: VLT/X-shooter redshift",
  "submitter": "Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>",
  "eventId": "GRB 150821A"
}