{
  "bibcode": "2017GCN.22056....1S",
  "body": "P. Schady (MPE) reports:\n\nObservations of the field of GRB 171027A (Swift trigger 783479; D'Avanzo\net al., GCN #22053) were carried out simultaneously in g'r'i'z' with GROND\n(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at\nESO La Silla Observatory (Chile).\n\nObservations started at 08:51 UT on 27-10-2017, 28.4 mins after the GRB\ntrigger. They were performed during astronomical twilight, at an average\nseeing of 1.4\" and at an average airmass of 1.4.\n\nUsing a total exposure of 4.4 min, no source is detected within the 2.1\"\nenhanced Swift/XRT error circle (Evans et al., GCN 22054) down to the\nfollowing 3 sigma upper limits (all in AB):\n\ng' > 23.1\nr' > 23.1\ni' > 22.3\nz' > 22.2\n\nGiven magnitudes are calibration against PanSTARRS and are not corrected\nfor the expected Galactic foreground extinction corresponding to a\nreddening of E_(B-V)=0.12 mag in the direction of the burst (Schlafly &\nFinkbeiner 2011).\n\nI acknowledge the excellent support provided by Angela Hempel in obtaining\nthese data.",
  "circularId": 22056,
  "createdOn": 1509103023000,
  "email": "pschady@mpe.mpg.de",
  "subject": "GROND observations of GRB 171027A",
  "submitter": "Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>",
  "eventId": "GRB 171027A"
}