{
  "bibcode": "2021GCN.30988....1P",
  "body": "N. Pankov (HSE), S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI, \nHSE)  report on behalf of IKI GRB FuN:\n\nWe observed  the GRB 210610B (Page  et al., GCN 30170) with \nSintesz-Newton 350mm f/5 telescope of CrAO observatory. Observation \nstarted on 2021-06-10 (UT) 22:07:10, and continued on   2021-06-11 (UT) \n20:22:38,  2021-06-12 (UT) 20:39:03, and 2021-06-13 (UT) 19:38:28. The \nseries consists of images with an exposure of 300 s in a Clear filter.\n\nThe optical afterglow  first reported by UVOT team (Page  et al., GCN \n30170) is clearly detected in each epoch.\n\nPreliminary photometry of the stacked images is following\n\nDate       UT start   t-T0    Filter Exp.     OT    err   UL(3)\n                      (mid, days)       (s)\n\n2021-06-10 22:07:10   0.10293  Clear 5*300    17.20 0.03  20.5\n2021-06-10 n/d        0.12658  Clear 5*300    17.28 0.08  21.1\n2021-06-10 n/d        0.14409  Clear 5*300    17.28 0.06  21.1\n2021-06-10 n/d        0.16159  Clear 5*300    17.29 0.06  21.1\n2021-06-11 20:22:38   1.02165  Clear 8*300    19.58 0.10  21.2\n2021-06-11 20:50:32   1.04103  Clear 6*300    19.50 0.09  21.2\n2021-06-11 21:33:21   1.07077  Clear 17*300   19.69 0.09  21.5\n2021-06-12 20:39:03   2.03479  Clear 14*300   20.57 0.19  21.5\n2021-06-13 19:38:28   3.02571  Clear 20*300   21.26 0.17  21.8\n\nThe photometry is based on nearby USNO-B1.0 (R2) stars\nUSNO_B10-1043-00282648\nUSNO_B10-1043-00282621",
  "circularId": 30988,
  "createdOn": 1635163625000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 210610B: Sintesz-Newton/CrAO optical observations",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 210610B"
}