{
  "bibcode": "2017GCN.21375....1G",
  "body": "C. Guidorzi (U. Ferrara), C.G. Mundell (U. Bath), A. Gomboc (U. Nova \nGorica), S. Kobayashi, I.A. Steele (LJMU) on behalf of a large \ncollaboration report:\n\nWe began observing Swift GRB 170728B (Cenko et al. GCN 21371) on July \n28, 23:06:47 UT (208 seconds since the GRB trigger) with 2-m Liverpool \nTelescope with RINGO3 polarimeter and IO:O camera in the SDSS R filter. \nWe clearly detect the optical counterpart (D'Avanzo et al. GCN 21373; \nHeintz et al. GCN 21374) with r'=20.43 +- 0.12 mag in a 6x10s frame at a \nmid time of 36.5 minutes since GRB, as calibrated against nearby \nPan-STARRS1 sources.",
  "circularId": 21375,
  "createdOn": 1501303811000,
  "email": "guidorzi@fe.infn.it",
  "subject": "GRB 170728B: LT afterglow confirmation",
  "submitter": "Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>",
  "eventId": "GRB 170728B"
}