{
  "bibcode": "2014GCN.17040....1X",
  "body": "D. Xu (DARK/NBI), P. M. Vreeswijk (Weizmann), J. P. U. Fynbo\n(DARK/NBI), V. D'Elia (ASI/ASDC and INAF/Roma), K. Wiersema,\nN. R. Tanvir (Univ. Leicester), A. de Ugarte Postigo (IAA-CSIC),\nS. Covino (INAF/OAB) report on behalf of a larger collaboration:\n\nWe observed the optical afterglow of the Swift GRB 141109A (D'Avanzo\net al., GCN 17037), using the X-shooter spectrograph at ESO's\nVLT. Observations started at 07:45 UT on 2014 Nov 9 (1.9 hr after the\nGRB), and consisted of 2x1200 s exposures in each of the UVB, VIS, and\nNIR arms, covering the wavelength range 3000-20,000 AA.\n\nIn the acquisition image, we detect a point source, which is not\ndetected in the SDSS, at the position (J2000):\n\n RA = 09:38:07.44\n Dec = -00:36:29.9\n\nwith an uncertainty of about 0.5\". This position is consistent with\nthat of the NIR afterglow reported by Covino et al. (GCN 17039).  We\nmeasure a (preliminary) magnitude of R=19.2+-0.1 (Vega).\n\nWe detect a variety of absorption features throughout the entire\nspectrum. In particular, a wide trough is visible centered around 4800\nAA, which we interpret as due to H I absorption at redshift z~3.\nIdentification of several metal features as due to, among others, Si\nII, C II, Fe II, C IV, SiIV, allows us to refine the value to\nz=2.993. The presence of several fine structure lines of Fe II, Si II,\nO I, Ni II and C II confirms this is the redshift of the GRB.\n\nWe note the presence of two strong intervening system at z ~ 1.67 and\nz ~ 2.5 (detected in Mg II).\n\nWe acknowledge excellent support from the ESO observing staff at\nParanal, in particular Valentin Ivanov and Marcelo Lopez. We also\nthank the visiting astronomer Simone Zaglia from the ESO-GAIA survey,\nwho made these observation possible.",
  "circularId": 17040,
  "createdOn": 1415529809000,
  "email": "paul.vreeswijk@weizmann.ac.il",
  "subject": "X-shooter redshift of GRB 141109A",
  "submitter": "Paul Vreeswijk at Weizmann Inst of Science  <paul.vreeswijk@weizmann.ac.il>",
  "eventId": "GRB 141109A"
}