{
  "bibcode": "2011GCN.12193....1B",
  "body": "E. Berger (Harvard) reports on behalf of a larger collaboration:\n\n\"We obtained spectroscopic observations of the candidate optical counterpart\n(GCN 12192) of the LAT burst GRB110721A (GCN 12188) with GMOS on the\nGemini-South 8-m telescope starting on 2011 July 24.20 UT.  A total of 3600\nsec was obtained on source with a wavelength coverage of about 4000-8100\nang.  We find two clear absorption features at 5487 and 5436 ang, with a\nsignificant decline in flux at shorter wavelengths, but to a non-zero\nlevel.  The two features match CaII H&K at a redshift of z=0.382, or could\nalternatively represent Ly-alpha absorption with the highest redshift being\nz=3.512.  No other features are detected at wavelengths corresponding to\nother typical lines at either redshift.  Given the detectable flux blueward\nof 5430 ang (down to at least 4600 ang), and the fact that the source\nappears to be extended in our i-band acquisition image (with seeing of about\n0.7\"), we consider the possibility that the object is an early-type galaxy\nat z=0.382 to be more likely.\n\nWe thank Jochen Greiner for sharing a finding chart of GRB110721A from GROND\ndata.\"",
  "circularId": 12193,
  "createdOn": 1311520298000,
  "email": "eberger@cfa.harvard.edu",
  "subject": "GRB 110721A: Gemini-South spectroscopy of the potential optical counterpart",
  "submitter": "Edo Berger at Harvard  <eberger@cfa.harvard.edu>",
  "eventId": "GRB 110721A"
}