{
  "bibcode": "2011GCN.12770....1S",
  "body": "S. Schulze (U Iceland), S. Covino (INAF-OABr), H. Flores (GEPI/Obs. de  \nParis), J. P. U. Fynbo (DARK/NBI), B. Milvang-Jensen (DARK/NBI), J.  \nSollerman (U Stockholm), D. Xu (WIS) report on behalf of the X-shooter  \nGRB collaboration:\n\nWe observed the afterglow of GRB 111228A (Ukwatta et al. GCN 12737)  \nwith the ESO VLT equipped with the X-shooter spectrograph on 29  \nDecember 2011, beginning 07:40 UT (15.93 hr after the GRB). The  \nafterglow had an R-band brightness of 20.08 mag in a series of five  \nacquisition images with an exposure time of 30 s each (mid-exposure  \ntime = 15.98 hours). The magnitude is not corrected for Galactic  \nextinction.\n\nWe acquired four spectra with an exposure time of 600 seconds each,  \nbeginning at 07:47 UT. We detect several absorption lines\n\nwave_obs wave_rest  Ion     redshift\n(AA, vac)   (AA, vac)\n3880.28     2260.78     FeII     0.71634\n4023.15     2344.21     FeII     0.71620\n4075.26     2374.46     FeII     0.71629\n4089.47     2382.77     FeII     0.71627\n4422.70     2576.88     MnII    0.71630\n4439.44     2586.65     FeII     0.71629\n4453.10     2594.50     MnII    0.71636\n4462.57     2600.17     FeII     0.71626\n4799.05     2796.35     MgII    0.71618\n4811.32     2803.53     MgII    0.71616\n4896.33     2852.96     MgI     0.71623\n6753.24     3934.78     CaK    0.71630\n6813.09     3969.59     CaH    0.71632\n\nat a common redshift of z = 0.71627 +/- 0.00002. In addition we detect  \n[OIII]5007 at z_em = 0.71635, similar to the absorption line redshift.  \nOur measurements confirm the results by of Cucchiara et al (GCN 12761)  \nand Palazzi et al (GCN 12763) and are similar to Dittmann et al (GCN  \n12759) and Xu et al (GCN 12764).\n\nThe seeing conditions over the entire campaign were around 0.8 arcsec.\n\nWe acknowledge the support of the VLT staff, in particular Claudio  \nMelo and Christophe Martayan.",
  "circularId": 12770,
  "createdOn": 1325186399000,
  "email": "steve@raunvis.hi.is",
  "subject": "GRB 111228A: X-shooter spectroscopy",
  "submitter": "Steve Schulse at U. of Iceland  <steve@raunvis.hi.is>",
  "eventId": "GRB 111228A"
}