{
  "bibcode": "2009GCN..9219....1T",
  "body": "N. Tanvir (U. Leicester), A. Levan (U. Warwick), K. Wiersema (U.\nLeicester), J. Fynbo, J. Hjorth (DARK/NBI), P. Jakobsson (Reykjavik)\nreport on behalf of a larger collaboration:\n\nWe observed the afterglow of GRB 090423 with ISAAC on the VLT,\nbeginning about 01:30 (UT), approximately 17.5 hours post-burst.\n\nOur provisional analysis shows a clear continuum at red wavelengths,\nbut no flux below about 11200A, consistent with a break due to\nLyman-alpha at a redshift z~8.2.  However, we caution that we have not\nyet carefully calibrated the instrumental response, and further work\nis required to confirm this result.\n\nWe thank the VLT observers for their excellent support in obtaining\nthese data, particularly Valentin Ivanov and Giovanni Carraro.",
  "circularId": 9219,
  "createdOn": 1240557635000,
  "email": "nrt@ast.cam.ac.uk",
  "subject": "GRB 090423: VLT/ISAAC spectroscopy",
  "submitter": "Nial Tanvir at IofA U.Cambridge  <nrt@ast.cam.ac.uk>",
  "eventId": "GRB 090423"
}