{
  "bibcode": "2010GCN.10782....1A",
  "body": "P. Afonso, P. Schady, T. Kruehler and J. Greiner (all MPE Garching) \nreport on behalf of the GROND team:\n\nWe observed the field of GRB 100518A (Mereghetti et al., GCN 10772) \nsimultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, \n405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile).\n\nObservations started at 09:12 UT on May 19, 21.7 hours after the GRB \ntrigger, and continued for 1 hour.\n\nIn stacked images of 50 min total integration time in g'r'i'z' we detect \nthe optical afterglow (Cano et al., GCN 10776) in r'i' and z'.\n\nPreliminary photometry yields the following AB magnitudes and upper limits:\n\ng' > 25.3\nr' = 23.8 +- 0.1\ni' = 23.6 +- 0.2\nz' = 23.5 +- 0.2\n\ncalibrated against the GROND zeropoints and 2MASS field stars. After \ncorrecting for the foreground reddening of E(B-V)=0.07 (Schlegel et al. \n1998) and assuming no intrinsic extinction, a fit with Hyper-z \n(Bolzonella et al. 2000) results in a preliminary photometric redshift \nof z = 4.0+0.3-0.5.",
  "circularId": 10782,
  "createdOn": 1274282937000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 100518A: GROND afterglow observation and photo-z",
  "submitter": "Thomas Kruehler at MPE/MPI  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 100518A"
}