{
  "submitter": "Alexander Moskvitin at SAO RAS <mosk@sao.ru>",
  "submittedHow": "web",
  "bibcode": "2025GCN.40761....1M",
  "circularId": 40761,
  "body": "A. Moskvitin, O. Spiridonova, Yu. Sotnikova (SAO RAS),\nA. Ghosh, S. Razzaque (CAPP, University of Johannesburg)\n\nWe observed the field of the GRB 250617B (Page et al., GCN 40760) \nwith SAO RAS 1-m telescope Zeiss-1000 equipped with CCD-photometer.\nWe obtained series of 60, 120 and 300 sec. exposures in Rc band \nand also one BVIc series. Observations started on 21:28:06 UT, \nsince 26 minutes after the trigger.\n\nThe OT (Page et al., GCN 40760) is clearly visible in individual images \nwith the brightness of R = 18.31 +/- 0.04 (t_mid - T0 = 0.5444 hours) \nand R = 18.66 +/- 0.04 (t_mid - T0 = 0.7635 hours).\n\nThis preliminary photometry is calibrated against R2 magnitudes \nof following nearby USNO-B1 stars and not corrected for the Galaxy \nextinction.\n\nR.A.       Dec. (2000)   R2\n22:11:38.4 +32:43:48.4   14.880 \n22:11:19.9 +32:44:17.5   15.280 \n22:11:41.0 +32:40:41.2   15.070 \n22:11:45.2 +32:42:19.8   14.690\n\nObservations are ongoing.",
  "format": "text/plain",
  "createdOn": 1750200897844,
  "eventId": "GRB 250617B",
  "subject": "GRB 250617B: SAO RAS optical observations"
}