{
  "bibcode": "2018GCN.22504....1S",
  "body": "P. Schady and S. Steinmassl (both MPE) report:\n\nWe observed the field of GRB 180316A (Swift trigger 814677; Melandri et\nal., GCN #22500) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.\n2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at 06:46 UT on March 16, 1.8 hours after the GRB\ntrigger. They were performed at an average seeing of 1.5\" and at an\naverage airmass of 1.5.\n\nWe clearly detect the NIR/optical transient of GRB 180316A within the\nenhanced XRT position (Evans et al., GCN #22501), in agreement with the\noptical transient detected with MASTER (Lipunov et al., GCN #22502,\n#22503). Based on the first 4 minutes of exposure, we measure the\nfollowing magnitudes (all in AB system):\n\ng' = 19.4 +/- 0.1 mag\nr' = 19.0 +/- 0.1 mag\ni' = 18.9 +/- 0.1 mag\nz' = 18.8 +/- 0.1 mag\nJ = 18.2 +/- 0.1 mag\nH = 18.0 +/- 0.1 mag\nK = 17.8 +/- 0.2 mag\n\nGiven magnitudes are calibrated against GROND zeropoints in g'r'i'z' and\n2MASS field stars in JHK, and are not corrected for the Galactic\nforeground extinction corresponding to a reddening of E_(B-V)= 0.24 in the\ndirection of the burst (Schlafly & Finkbeiner 2011).\n\nWe acknowledge the excellent support from the TiO and the current observer\nat the 2.2m in La Silla, Sam Kim and Charlotte Brand.",
  "circularId": 22504,
  "createdOn": 1521196827000,
  "email": "pschady@mpe.mpg.de",
  "subject": "GROND observations of GRB 180316A",
  "submitter": "Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>",
  "eventId": "GRB 180316A"
}