{
  "bibcode": "2019GCN.26553....1V",
  "body": "Title: GRB 191221B: VLT/X-shooter redshift\n\nJ.-B. Vielfaure (CNRS, Paris Obs.), M. Arabsalmani (ICRAR/UWA), K. E.\nHeintz (Univ. Iceland), N. R. Tanvir (Univ. Leicester), A. de Ugarte\nPostigo (HETH/IAA-CSIC), D. B. Malesani (DTU Space), J. P. U. Fynbo\n(DAWN/NBI), K. Wiersema (Univ. Warwick), S. D. Vergani (CNRS, Paris Obs.),\nD. Xu (NAO/CAS), G. Pugliese (Univ. Amsteram), S. Schulze (WIS), D.\nBurgarella (AMU, CNRS, CNES, LAM), report on behalf of the Stargate\ncollaboration:\n\nWe observed the optical afterglow of GRB 191221B (Laha et al., GCN 26534;\nLongo et al., GCN 26549; Lipunov et al., GCN 26537). using the ESO VLT UT2\n(Kueyen) equipped with the X-shooter spectrograph. Our spectra cover the\nwavelength range 3000-21000 AA, and consist of 2 exposures by 600 s each.\nThe observation mid time was 2019 Dec 22.2707 UT (9.843 hr after the GRB).\n\nIn a 15 s image taken with the acquisition camera on Dec 22.2592 UT, we\ndetect the optical afterglow, for which we measure a magnitude r = 17.13 +-\n0.01 AB (calibrated against nearby stars from the Skymapper catalog; Wolf\net al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574).\n\nWe detect several absorption profiles in the GRB spectrum including MgII,\nMgI, SiII, CIV, AlII, NiII, and FeII lines. From these metal lines we infer\na redshift z=1.148 for the GRB, consistent with the redshift reported by\nSwift/UVOT tram (GCN 26538). We also detect the MgII absorption profile\ncorresponding to an intervening system at z=0.961.\n\nWe acknowledge excellent support from the ESO observing staff in Paranal,\nin particular Pascale Hibon, Francisco Belmar, and Trystyn Berg.",
  "circularId": 26553,
  "createdOn": 1577012321000,
  "email": "mar.arabsalmani@gmail.com",
  "subject": "GRB 191221B: VLT/X-shooter redshift",
  "submitter": "Maryam Arabsalmani at University of Melbourne  <mar.arabsalmani@gmail.com>",
  "eventId": "GRB 191221B"
}