{
  "bibcode": "2009GCN..9015....1D",
  "body": "A. de Ugarte Postigo, S. D�Odorico (ESO PI), J. Vernet, A. Modigliani,\nS. Ramsay from ESO Commissioning team;\nS. Covino (INAF Brera), H. Flores (Obs. Paris), J. Fynbo, J. Hjorth\n(NBI/DARK, U. Copenhagen) and R.A.M.J. Wijers (Astr. Institute,\nU. Amsterdam) from the X-shooter GRB team;\nF. Hammer (Obs. Paris), L. Kaper (Astr. Institute, U. Amsterdam),\nP. Kjaergaard (NBI, U. Copenhagen), S. Randich (INAF Arcetri) as\nX-shooter PIs;\nP.J. Groot (Radboud Univ. Nijmegen) from the X-shooter Science Team.\n\nOn March 15.22 UT we initiated observations of GRB 090313 (Chornock\net al., GCNC 8979; Mao et al., GCNC 8980) with X-shooter at the ESO\nMelipal telescope of the Paranal Observatory. X-shooter is the first\nof the second-generation VLT instruments and includes three\nEchelle spectrographs, the Ultraviolet/Blue (UVB), the Visible (VIS)\nand the Near Infrared (NIR), which combined provide a fixed spectral\nformat and cover in one shot the spectral range 3000 - 24000 A at\nmedium spectral resolution (R = 4000 - 10000 depending on the arm\nand slit width). The mean epoch of the observation was 45.3 hours\nafter the burst, when the afterglow had faded to R ~ 21.6 (Perley et\nal. GCNC 9001; Cobb et al. GCNC 9008). In the 4 x 1500 s combined\nspectrum we clearly detect continuum above 5580 A with several\nabsorption lines; below this, the signal is dominated by background\nemission produced by the nearby Moon (90 % illumination at 37 deg\nfrom the field). The spectrum indicates an absorption redshift\nof z = 3.3721 � 0.0004 (consistent with that measured by Chornock et\nal., GCNC 8994 and Thoene et al., GCNC 9012) through the detection of\nSi II (1304.5), C II (1334.5), Si IV (1393.8), Si IV (1402.8), Si II\n(1526.7), C IV (1548.2,1550.8), Fe II (1608.5), Fe II (1611.2),\nAl III (1854.7), Al III (1862.8), Zn II (2062.6), Fe II (2600.1),\nMg II (2796.3, 2803.5) and Mg I (2853.0). The intervening system\nidentified by Thoene et al. (GCNC 9012) is resolved into multiple\ncomponents through the detection of Fe II, Mg II and Mg I lines with\nits main absorption at redshift 1.800. A further system at z = 1.959\nshows Fe II, Mg II and Mg I absorption.\n\nThe spectra of GRB 090313 will be made public on the ESO web as other\ndata of scientific relevance obtained during the commissioning of the\ninstrument.\n\n[GCN OPS NOTE923mar09): Per author's request, the Groot-author's\naffiliation was changed.]",
  "circularId": 9015,
  "createdOn": 1237777083000,
  "email": "deugarte@iaa.es",
  "subject": "X-shooter observations of GRB 090313",
  "submitter": "Antonio Deugarte at IAA-CSIC  <deugarte@iaa.es>",
  "eventId": "GRB 090313"
}