{
  "bibcode": "2016GCN.18887....1C",
  "body": "T.-W. Chen, T. Kruehler and J. Greiner (all MPE Garching) report on\nbehalf of the GROND team:\n\nWe observed the field of GRB 160117B (Sonbas et al., GCN 18875) \nsimultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, \n405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).\n\nObservations started at 00:54 UT on 2016-01-18, about 11 hours after the \nGRB trigger. The optical afterglow (Sonbas et al., GCN 18875; Yurkov et \nal., GCN 18877; Kruehler et al., GCN 18878, Malesani et al.\nGCN 18884, Hentunen et al. GCN 18885, de Ugarte Postigo et al. GCN \n18886) is clearly detected in our images.\n\nBased on 29 min of total exposure in g'r'i'z' and 24 min in JHK at a \nmidtime of 01:12 UT on 2016-01-18, we estimate the following preliminary \nmagnitudes (all in the AB system):\n\n  g' = 20.8 +- 0.1 mag\n  r' = 20.7 +- 0.1 mag\n  i' = 20.6 +- 0.1 mag\n  z' = 20.4 +- 0.1 mag\n  J  = 20.0 +- 0.2 mag\n  H  = 19.8 +- 0.2 mag\n  K  > 18.9 mag\n\nGiven magnitudes are calibrated against GROND zeropoints as well as \n2MASS field stars and are not corrected for the expected Galactic \nforeground extinction corresponding to a reddening of E_(B-V)=0.058 mag \nin the direction of the burst (Schlafly & Finkbeiner 2011).",
  "circularId": 18887,
  "createdOn": 1453114459000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 160117B: GROND optical/NIR afterglow observations",
  "submitter": "Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 160117B"
}