{
  "bibcode": "2018GCN.23371....1S",
  "body": "P. Schady (Univ. of Bath) and J. Bolmer (MPE, Garching) report:\n\n\nWe observed the field of GRB 181022A (Swift trigger 868312; Marshall et al., GCN #23364) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).\n\n\nObservations started at 01:53 UT on 2018-10-23, 8.4 hrs after the GRB trigger. They were performed at an average seeing of 1.4\" and average airmass of 1.8.\n\n\nBased on a total of 16 mins integration time, we do not detect a source within the Swift-XRT error circle reported by Marshall et al. (GCN #868312) down to the following 3 sigma AB magnitudes:\n\n\ng' > 22.8 mag\n\nr' > 22.9 mag\n\ni' > 22.7 mag\n\nz' > 22.5 mag\n\nJ > 21.3 mag\n\nH > 20.8 mag\n\nK > 18.9 mag\n\n\nThe given limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.01 in the direction of the burst (Schlafly & Finkbeiner 2011).\n\n\nWe thank Markus Rabus for the excellend support from La Silla.",
  "circularId": 23371,
  "createdOn": 1540296446000,
  "email": "p.schady@bath.ac.uk",
  "subject": "GRB 181022A: GROND upper limits",
  "submitter": "Patricia Schady at Swift  <p.schady@bath.ac.uk>",
  "eventId": "GRB 181022A"
}