{
  "bibcode": "2017GCN.21382....1C",
  "body": "A. Cucchiara, D. Morris (U. of Virgin Islands), and\nC. Guidorzi (U. Ferrara), reports on behalf of a larger\ncollaboration:\n\n\"On July 28.38 UT  (T_0 +2.1h) we began observing the center\nof the field of GRB 170728A (Cannizzo et al. GCN 21367,\nEvans et al. GCN 21368) using the Las Cumbres Observatory\n1m telescope in Cerro Tololo.\nWe performed a series of 4x240s observations in R and Ic band\nfor a total of 16 minutes on sky in each filter at average\nairmass of 1.8. Further observations were requested in Sloane\ni' filter for a total of 360s.\n\nIn the full combined R and I+i' stacks we identified no optical\ncounterpart within the center of Swift-XRT refined position\n(Evans et al. GCN 21368) at the following 3-sigma limits:\n\nR > 18.9 mag\nI > 18.4 mag\n\nThese magnitudes are calibrated against nearby USNO-B1 sources,\nand are not corrected for Galactic extinction.\"",
  "circularId": 21382,
  "createdOn": 1501339653000,
  "email": "antonino.cucchiara@uvi.edu",
  "subject": "GRB 170728A: LCO observations",
  "submitter": "Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>",
  "eventId": "GRB 170728A"
}