{
  "bibcode": "2016GCN.19027....1W",
  "body": "P. Wiseman, F. Knust, J. Greiner (all MPE Garching) report on behalf of\nthe GROND team:\n\nWe observed the field of GRB 160220A (Swift trigger 674670; Lien et al.,\nGCN #19023) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at  05:46 UT on 2016-02-20, 4.5 hrs after the GRB\ntrigger. They were performed at an average seeing of 1.5\" and at an\naverage airmass of 1.6.\n\nWe do not find any single point source within the 1.9\" Enhanced Swift-XRT\nerror circle reported by Evans et al. (GCN #19025). Based on 36.00 min of\ntotal exposures in g'r'i'z' and 30.00 min in JHK, at a mid-time of 06:49\nUT, we estimate preliminary upper limiting magnitudes (AB system) of\n\ng' > 23.4 mag,\nr' > 23.9 mag,\ni' > 23.6 mag,\nz' > 23.3 mag,\nJ  > 21.6 mag,\nH  > 20.9 mag, and\nK  > 18.0 mag.\n\nGiven limits are calibrated against GROND zeropoints as well as 2MASS\nfield stars and are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V)=0.12 mag in the\ndirection of the burst (Schlafly & Finkbeiner 2011).",
  "circularId": 19027,
  "createdOn": 1455955593000,
  "email": "wiseman@mpe.mpg.de",
  "subject": "GRB 160220A: GROND Optical/NIR Upper Limits",
  "submitter": "Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>",
  "eventId": "GRB 160220A"
}