{
  "bibcode": "2007GCN..6843....1P",
  "body": "D. A. Perley (UCB), J. X. Prochaska (UCSC), J. S. Bloom (UCB), and G. \nSmith (UCO/Lick) report on behalf of the GRAASP collaboration:\n\nWe observed GRB 071003 (Schady et al., GCN 6837) with Keck/HIRESr \nstarting at UT 10:24 for one exposure of 1700s.  The data were acquired \nthrough very high airmass and have a low S/N ratio (~1 per 1.3 km/s \npixel at 5000A).\n\nWe identify no obvious absorption features in either the 2D image nor 1D \nspectrum.  Allowing for the following priors, we place the following \nupper limits on the GRB redshift:\n\n1.  Assuming the GRB host galaxy would emit no flux below the Lyman \nlimit, we infer z_GRB < 3.4\n\n2.  Assuming the GRB host galaxy would imprint a damped Lya profile on \nthe spectrum, we infer z_GRB < 2.5\n\n3.  Assuming the GRB host galaxy would imprint a strong MgII absorber on \nthe spectrum (EW > 1A), we infer z_GRB < 1.\n\nGiven these constraints and the U-band detection from Mishra et al. (GCN \n6840), it is possible that this GRB is at low redshift.  We encourage \nfollow-up observations to search for, or place limits on, a low-redshift \nhost galaxy or associated supernova.",
  "circularId": 6843,
  "createdOn": 1191453144000,
  "email": "dperley@astro.berkeley.edu",
  "subject": "GRB 071003: Keck HIRES spectroscopy",
  "submitter": "Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>",
  "eventId": "GRB 071003"
}