{
  "bibcode": "2017GCN.21419....1V",
  "body": "A. Volnova (IKI),  A. Kusakin (Fesenkov Astrophysical Institute), A.S. \nMoskvitin (SAO RAS), O.I. Spiridonova (SAO RAS),  R. Inasaridze (AbAO), I. \nReva (Fesenkov Astrophysical Institute),  E. Mazaeva (IKI), A. Pozanenko \n(IKI)   report on behalf of larger GRB follow-up collaboration:\n\nWe observed the field of the Swift GRB 170728B (Cenko et al., GCN 21371) \nwith Zeiss-1000 of SAO RAS (July 29, August 4,5 ), AS-32 telescope of AbAO \n(July 29) and  Zeiss-1000  telescope of Tien Shan Astronomical Observatory \n(July  30,31 August 1,6).  Below we report the photometry of the optical \nafterglow (D'Avanzo et al., GCNs 21372, 21373; Heintz  et al., GCN 21374; \nGuidorzi   et al., GCN 21375) and upper limits of our observations. \nPreliminary photometry is following:\n\nDate       UT start   t-T0    Filter Exp. OT     Err. UL  Telescope\n                       (mid, days)     (s)             (3 sigma)\n\n2017-07-29 00:41:51  0.07228  R    600   n/d     n/d  18.6  Z-1000 SAO\n2017-07-29 17:27:49  0.79594 CR   43*60  n/d     n/d  20.4  AS-32  AbAO\n2017-07-30 16:12:56  1.79815  R  97*120   21.93  0.25  22.1  Z-1000 TSHAO\n2017-08-01 15:12:51  3.72304  R  60*120  n/d     n/d  21.6  Z-1000 TSHAO\n2017-08-04 00:41:51  5.98081  R  41*300   22.6  0.23  22.8  Z-1000 SAO\n\nThe photometry is based on nearby USNO-B1.0 stars\n\n1601-0108291 15:52:31.54 +70:09:31.7 R2 17.95\n\n1601-0108289 15:52:28.99 +70:09:26.3 R2 18.08\n\n1601-0108260 15:51:57.87 +70:09:53.8 R2 16.87\n\n1601-0108254 15:51:50.88 +70:08:41.2 R2 15.04\n\n1601-0108262 15:52:03.24 +70:07:32.0 R2 16.01\n\nCoordinates of the afterglow obtained from observation on July 30 are \n(J2000)\n15 51 55.5179 +70 07 21.123  with uncertainties on both coordinates of  0.2 \narces which is compatible with coordinates of TNG (D'Avanzo et al., GCN \n21373) and VLA (Fong  et al., GCN 21395). The  finding chart can be found in\nhttp://grb.rssi.ru/GRB170728B/GRB170728B_TShAO_R_170730.png\n\nThe light curve of the afterglow based on  observations above and photometry \nreported in GCNs (Dintinjana et al., GCN 21394; Watson GCN 21389;   D'Avanzo \net al., GCN 21372; Heintz  et al., GCN 21374; Guidorzi   et al., GCN 21375) \ncan be found in\nhttp://grb.rssi.ru/GRB170728B/GRB170728B_lc+GCNs_v2.png\nBased on our observation on July, 30 (~ 1.8 days after burst onset) one can \nsuggest that the OT experienced  rebrightening at that epoch.",
  "circularId": 21419,
  "createdOn": 1502101384000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 170728B: TShAO, SAO RAS and AbAO optical observations",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 170728B"
}