{
  "bibcode": "2011GCN.12225....1T",
  "body": "N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), S. B. Cenko (U. Berkeley)\nand T. Geballe (Gemini) report on behalf of a larger collaboration:\n\nWe observed the location of GRB 110731A (Oates et al. GCN12215) with\nthe GMOS-N instrument on Gemini-North (Mauna Kea), beginning at 1 Aug 2011\n09:07 UT.�� Spectroscopic observations totalling 3600s were obtained in good\nconditions using the B600 grating (spanning approximately 3800 A to 6650 A).��\nWe identify a broad Ly-alpha absorption feature and several absorption lines of\nO, C, Si and Al at a common redshift of z=2.83.�� This includes fine structure lines\nof O, C and Si, as seen in other GRB sight-lines, confirming that this is the\nredshift of the burst.\n\nProvisional calibration of the acquisition image gives a magnitude of R=22.0 for\nthe afterglow (uncorrected for foreground extinction of A_R ~ 0.5),�� suggesting\na fairly shallow rate of decay since the NOT epoch (Malesani et al. GCN12220).",
  "circularId": 12225,
  "createdOn": 1312205024000,
  "email": "nrt3@star.le.ac.uk",
  "subject": "GRB 110731A Gemini-N redshift",
  "submitter": "Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>",
  "eventId": "GRB 110731A"
}