{
  "bibcode": "2018GCN.23177....1M",
  "body": "E. Mazaeva (IKI), A. Pozanenko (IKI),  A. Kusakin (FAPHI), I. Reva \n(FAPHI),  A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger \nGRB follow-up collaboration:\n\nWe observed the field of GRB 180818B  (Marshall et al., GCN 23149; Veres \net al., GCN 23153) with Zeiss-1000 1-m telescope of Tien Shan \nAstronomical Observatory starting on August 08 (UT) 22:20:38. We \nobtained several images in R-filter.  Within enhanced XRT Swift-XRT \nposition (Beardmore et al., GCN 23151)  we do not detect any object.  In \n  particular we do not detect the afterglow candidate reported in  GCN \n23161 (Hu et al.) Preliminary photometry of the field is following.\n\nDate        UT start t-T0     Filter Exp.   OT   Err.   UL\n                      (mid, days)     (s)\n\n2018-08-18  22:20:38 0.42710  R      36*60  n/d  n/d    20.4\n\nThe photometry is based on several nearby USNO-B1.0 stars.",
  "circularId": 23177,
  "createdOn": 1535300259000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 180818B: TSHAO optical upper limit",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 180818B"
}