{
  "bibcode": "2018GCN.22818....1S",
  "body": "Tassilo Schweyer and Patricia Schady (MPE Garching) report:\n\nWe observed the field of GRB 180620A (Swift trigger 843211; Evans et al.,\nGCN #22807) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at 04:35 UT on 2018-06-21, 20 hours after the GRB\ntrigger. They were performed at an average seeing of 1.4\" and at an\naverage airmass of 1.7.\n\nWe detect a faint point source consistent with the position of the\nreported X-ray and optical afterglow (Elenin et al., GCN #22800; Osborne\net al., GCN #22802; Breeveld et al., GCN #22805). Based on a total\nexposures time of around 30mins we estimate the following AB magnitudes:\n\ng' = 23.9 +/- 0.1 mag\nr' = 23.4 +/- 0.1 mag\ni' = 23.1 +/- 0.1 mag\nz' > 23.2 mag\nJ > 21.2 mag\nH > 20.5 mag\nK > 19.3 mag\n\nGiven magnitudes are calibrated against PanSTARRS and 2MASS field stars\nand are not corrected for the expected Galactic foreground extinction\ncorresponding to a reddening of E_(B-V)=0.11 in the direction of the burst\n(Schlafly & Finkbeiner 2011).\n\nWe thank Markus Rabus for the excellent support from La Silla.",
  "circularId": 22818,
  "createdOn": 1529579772000,
  "email": "pschady@mpe.mpg.de",
  "subject": "GROND observations of GRB 180620A",
  "submitter": "Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>",
  "eventId": "GRB 180620A"
}