{
  "bibcode": "2009GCN.10246....1A",
  "body": "GRB 091109A: GROND confirmation of redshift z = 3.5\n\nP. Afonso, T. Kruehler, A. Rau, and J. Greiner (all MPE Garching) report\non behalf of the GROND team:\n\nGROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI\ntelescope at La Silla Observatory (Chile), reobserved the field of GRB\n091109A (Oates et al., GCN #10138) simultaneously in the g'r'i'z'JHK\nbands.\n\nObservations started 2009-11-20 00:42, 10.8 days after the trigger and\nlasted for an effective exposure of 75 min in g'r'i'z' and 60 min in JHK.\n\nAt the position of the optical afterglow (Guidorzi et al. GCN#10142,\nOates GCN#10143, Afonso et al., GCN #10158) we do not detect any source\ndown to a limiting magnitude of r' > 25.1.\n\nComparing with the brightness of r' = 23.6 +- 0.1 mag (AB) reported for\nthe 1st epoch (Afonso et al., GCN #10158), the last imaging clearly\nshows a fading of more than 1.5 magnitudes. The 1st epoch was hence\ndominated by afterglow light, favoring a redshift of around z = 3.5 +/-\n0.4.\n\nA thorough analysis of the VLT data (GCN # 10158) was limited by the\nvery low S/N of the optical spectrum and does not yield more precise\nredshift constraints.",
  "circularId": 10246,
  "createdOn": 1259947932000,
  "email": "pafonso@mpe.mpg.de",
  "subject": "GRB 091109A: GROND confirmation of redshift z = 3.5",
  "submitter": "Paulo M. J. Afonso at MPE  <pafonso@mpe.mpg.de>",
  "eventId": "GRB 091109A"
}