{
  "bibcode": "2011GCN.11954....1A",
  "body": "P. Afonso, J. Elliott, and J. Greiner (MPE Garching) report on behalf of\nthe GROND team:\n\nWe observed the field of GRB 110420A (Swift trigger 451757; Mangano et\nal., GCN #11941) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.\n2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla\nObservatory (Chile).\n\nObservations started at 09:34 UT on April 21, 22.5 hours after the GRB\ntrigger. They were performed at an average seeing of 1.8'' and at an\naverage airmass of 2.3.\n\nWe confirm the detection of the single point source reported by Oates et\nal. (GCN #11948).\n\nBased on the first 142-s exposures in r', we estimate a preliminary\nmagnitude (AB system) of\n\nr' = 20.6 +/- 0.1 mag.\n\nIn combination with the early UVOT detection, this would imply a decay\nslope of 0.85 between 700 s and 22.5 hours.\n\nGiven magnitudes are calibrated against GROND zeropoints and are not\ncorrected for the expected Galactic foreground extinction corresponding to\na reddening of E_(B-V)=0.014 mag in the direction of the burst (Schlegel\net al. 1998).",
  "circularId": 11954,
  "createdOn": 1303395496000,
  "email": "jonnyelliott@mpe.mpg.de",
  "subject": "GRB110420A: GROND detection of the Optical/NIR Afterglow Candidate",
  "submitter": "Jonny Elliott at MPE/GROND  <jonnyelliott@mpe.mpg.de>",
  "eventId": "GRB 110420A"
}