{
  "bibcode": "2006GCN..5002....1P",
  "body": "J. X. Prochaska (UCO/Lick Observatory), H.-W. Chen (U Chicago), J. S.  \nBloom (UC\nBerkeley), E. Falco, and A. K. Dupree (Harvard-Smithsonian CfA)  \nreport on behalf of the\nGRAASP collaboration:\n\n\"We have further analyzed the echelle spectra of GRB060418 (Falcone  \net al.\nGCN 4966), obtained using MIKE on the Magellan Clay telescope (Dupree  \net al.\nGCN 4969).  We report the detection of ZnII, SiII, SiII*, FeII, FeII*,\nMgII, MgI, AlIII, CIV and NiII transitions among others at a redshift\nz=1.4901 +/- 0.0001.  The relative populations of the excited\nFeII levels are similar to GRB051111 (PHB06, astro-ph/0601057); the  \nJ=7/2 to\nJ=1/2 states follow a Boltzmann distribution with T=1000-5000K.\nBut, following GRB051111 and GRB050730, we interpret the FeII excitation\nas the result of indirect UV pumping by the GRB afterglow.  The  \ndetection\nof strong MgI absorption places this gas (and presumably the majority of\nlow-ion gas) at a distance r>50pc from the GRB.  Finally, we measure\n[Si/Fe]=+0.5dex indicating a modest dust-to-metals ratio.\n\nThis message may be cited.\"",
  "circularId": 5002,
  "createdOn": 1145899654000,
  "email": "xavier@ucolick.org",
  "subject": "GRB060418: Further Analysis of MIKE Spectroscopy",
  "submitter": "Jason Prochaska at UCO/Lick Obs  <xavier@ucolick.org>",
  "eventId": "GRB 060418"
}