{
  "bibcode": "2009GCN.10053....1X",
  "body": "Dong Xu, Johan P.U. Fynbo (DARK/NBI), Nial R. Tanvir (Univ. Leicester), \nJens Hjorth, Giorgos Leloudas, Daniele Malesani (DARK/NBI), Pall \nJakobsson (Univ. Iceland), Paul A. Wilson (NOT and Univ. Oslo), Johannes \nAndersen (NBI and NOT), report on behalf of a larger collaboration:\n\nWe observed the optical afterglow of GRB 091020 (Racusin et al., GCN \n10048; Gorbovskoy et al., GCN 10052) with the Nordic Optical Telescope \nequipped with ALFOSC. We detect the afterglow with a magnitude R ~ 20, \nbased on a nearby USNO star, with mean time Oct 21.220 UT (0.315 days \nafter the GRB).\n\nWe secured low-resolution spectroscopy (30 min exposure), covering the \nwavelength range 3500-9100 AA, starting on Oct. 21.231 UT. Wavelength \ncalibration was carried out using archival frames.\n\nIn a preliminary analysis we detect several absorption features, which \nwe interpret as FeII 2344, 2374, 2382, Al III 1854, 1862, Mg II 2798 (Mg \nII 2803 is blended with the telluric A band), all at the common z = \n1.71. There is flux in the spectrum down to ~3800 AA, setting a firm \nupper limit z < 2.13 to the GRB redshift.",
  "circularId": 10053,
  "createdOn": 1256113462000,
  "email": "malesani@astro.ku.dk",
  "subject": "GRB 091020: NOT spectroscopic redshift",
  "submitter": "Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@astro.ku.dk>",
  "eventId": "GRB 091020"
}