{
  "bibcode": "2021GCN.29689....1P",
  "body": "N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) \nreport  on behalf of GRB IKI FuN:\n\nWe observed the field of GRB 210321A (Dichiara  et al., GCN 29677)  with \nAZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-03-21 \n(UT) 14:20:37. The optical afterglow (Siegel  et al., GCN 29679; Butler \net al., GCN 29680;   Lipunov et al., GCN 29683; Heintz et al., GCN \n29684; de Ugarte Postigo et al., GCN 29685; Xin et al. GCN 29687) is \nclearly detected in a combined image. Preliminary photometry of the \nafterglow in the combined image is following\n\nDate       UT start   t-T0       Filter Exp.   OT   Err.  UL(3sigma)\n                       (mid, days)        (s)\n\n2021-03-21 14:20:37   0.31199    R      45*60  20.1 0.14  20.5\n\nThe photometry is based on the nearby USNO-B1.0 stars\nUSNO-B1.0_id R2\n1601-0068003 15.84\n1600-0068970 16.18\n1601-0068018 16.54\n1601-0067995 16.23",
  "circularId": 29689,
  "createdOn": 1616411729000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 210321A: Mondy optical observations",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 210321A"
}