{
  "bibcode": "2017GCN.21183....1C",
  "body": "A. Cucchiara, D. Morris (U. of Virgin Islands), C. Guidorzi\n(U. Ferrara), reports on behalf of a larger collaboration:\n\n\n\"On June 1.00 UT  (T_0 +2.0h) we began observing the center\nof the field of GRB 170531B (Evans et al. GCN 211171)\nusing the Las Cumbres Observatory 1m Sutherland facility.\nWe performed a series of 10x60s observations in R and I band\nfor a total of 10 minutes on sky in each filter. Seeing\nconditions were poor.\n\nWe identified no optical counterpart within the center of\nSwift-XRT refined position (Evans et al. GCN 21175), or at\nthe location of the identified  counterpart (Lipunov et al.\nGCN 21173, Pozanenko et al. GCN 21174, Schady et al. GCN 21178)\nat the following 3-sigma limits:\n\nR > 19.9 mag\nI > 19.6 mag\n\nThese magnitude are calibrated against nearby USNO-B1 sources,\nand are not corrected for Galactic extinction.\"",
  "circularId": 21183,
  "createdOn": 1496332144000,
  "email": "antonino.cucchiara@uvi.edu",
  "subject": "GRB 170531B: LCO observations",
  "submitter": "Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>",
  "eventId": "GRB 170531B"
}