{
  "bibcode": "2017GCN.21206....1M",
  "body": "E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) \nreport on behalf of larger GRB follow-up collaboration:\n\nWe observed the field of GRB 170519A (Ukwatta et al., GCN 21106) with\nAZT-33IK telescope of Sayan observatory (Mondy) starting on May 20 (UT) \n16:27:01. We took several images in R-filter with exposures of 120 s. \nThe optical afterglow (Ukwatta et al., GCN 21106; Izzo, et al., GCN \n21108) is clearly visible in single images.\n\nWe continued our observations on May 27 (UT) 16:28:02, i.e., ~8.5 days\nafter the BAT trigger. We took several R-filtered images. We do not \ndetect the optical counterpart in the enhanced XRT error circle \n(Beardmore et al., GCN 21107).\n\nPreliminary photometry of the afterglow is following:\n\nDate       UT start   t-T0    Filter  Exp.     OT     Err.     UL\n                                    (mid, days)      (s) \n        (3 sigma)\n\n2017-05-20 16:27:01  1.47708  R   10*120  19.99 0.03 22.8\n2017-05-20 17:07:02  1.50487  R   10*120  19.99 0.03 22.6\n2017-05-27 16:28:02  8.49905  R   39*120  n/d   n/d  22.6\n\nThe photometry is based on nearby SDSS stars reported by\nMazaeva et al. (GCN 21169).",
  "circularId": 21206,
  "createdOn": 1496689637000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 170519A: Mondy optical observations",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 170519A"
}