{
  "bibcode": "2018GCN.22840....1S",
  "body": "Patricia Schady (MPE Garching) reports:\n\nWe observed the field of GRB 180624A (Swift trigger 844192; Gibson et al.,\nGCN #22832) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at 04:42 UT on 2018-06-25, 14.9 hrs after the GRB\ntrigger. They were performed under poor seeing conditions and at an\naverage airmass of 1.5.\n\nA source is visible within the 1.5\" enhanced Swift-XRT error circle\nreported by GOAD et al. (GCN #22835), and consistent with the position of\nthe optical afterglow candidate reported by Guidorzi et al. (GCN #22839).\nThe source appears extended and most of the flux in the JHK bands is to\nthe NW of the  afterglow error circle.\n\nBased on a total of 22 min exposure time in g'r'i'z', we estimate\npreliminary AB magnitudes of\n\ng' = 21.5 +/- 0.1 mag\nr' = 20.2 +/- 0.1 mag\ni' = 19.9 +/- 0.1 mag\nz' = 19.6 +/- 0.1 mag\n\nA fit to the GROND optical SED implies a photometric redshift of\nz_phot=3.75+/-0.10.\n\nGiven magnitudes are calibrated against SDSS field stars and are not\ncorrected for the expected Galactic foreground extinction corresponding to\na reddening of E_(B-V)=0.04 in the direction of the burst (Schlafly &\nFinkbeiner 2011).\n\nWe thank Markus Rabus for the excellent support from La Silla.",
  "circularId": 22840,
  "createdOn": 1529914191000,
  "email": "pschady@mpe.mpg.de",
  "subject": "GRB 180624A: GROND observations",
  "submitter": "Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>",
  "eventId": "GRB 180624A"
}