{
  "bibcode": "2015GCN.18696....1X",
  "body": "D. Xu (NAOC/CAS), N. R. Tanvir (Univ. Leicester), D. Malesani \n(DARK/NBI), J. P. U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), J. \nSaario (NOT and Univ. Turku) report on behalf of a larger collaboration:\n\nWe observed the optical afterglow (Cenko, GCN 18692; Wiseman et al., GCN \n18694) of GRB 151215A (Gibson et al., GCN 18691) using the Nordic \nOptical Telescope (NOT) equipped with the AlFOSC camera and spectrograph.\n\nThe optical afterglow is clearly visible in our images, and we measure \nits brightness on Dec 15.160 UT (0.81 hr after the GRB) to be R = 20.07 \n+- 0.02 (Vega, assuming R = 16.31 for the USNO star at RA = 06:14:19.93, \nDec = +35:31:06.0).\n\nA sequence of three spectra of 1200 s each was carried out starting on \nDec 15.176 UT (1.2 hr after the trigger), covering the wavelength range \n3200-9000 AA.\n\nA wide trough is visible superimposed on the afterglow continuum, \nindicating Lyalpha absorption from neutral hydrogen. We also detect \nseveral narrow absorption features, which we interpret as due to, e.g., \nSi II, O I, Al II, all at a common redshift of z = 2.59. A preliminary \nfit to the Lyalpha profile yields an HI column density of 3x10^21 cm^-2, \nthough establishing the system as a DLA.",
  "circularId": 18696,
  "createdOn": 1450174544000,
  "email": "malesani@dark-cosmology.dk",
  "subject": "GRB 151215A: NOT spectroscopy and redshift",
  "submitter": "Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>",
  "eventId": "GRB 151215A"
}