{
  "createdOn": 1758540260238,
  "submittedHow": "web",
  "eventId": "GRB 250916A",
  "circularId": 41936,
  "submitter": "Nicolai Pankov at HSE, IKI RAS <colinsergesen@gmail.com>",
  "format": "text/plain",
  "body": "N. Pankov (HSE, IKI), A. Pozanenko (IKI), A. Moskvitin (SAO RAS), V. Rumyantsev (CrAO)\nreport on behalf of IKI-GRB-FuN.\n\nWe observed the field of the GRB 250916A (The Fermi GBM team, GCN 41839; Arya et al., GCN 41843; Cheung et al., GCN 41855; Osborne et al., GCN 41862; Waratkar and Grefenstette, GCN 41871; Godwin and Meegan, GCN 41876) with the Shajn 2.65m telescope of CrAO, equipped with CCD-photometer. The observations in the R-filter were carried out on epochs 2025-09-19, 2025-09-20, and 2025-09-21. The OT (Belkin et al., GCN 41847; Mohan et al., GCN 41858; Burkhonov et al., GCN 41860;  de Ugarte Postigo et al., GCN 41863; Moskvitin et al., GCN 41870; Zheng and Filippenko, GCN 41873; Pankov et al., GCN 41892; Hall et al., GCN 41921; Moskvitin et. al, GCN 41934) is clearly detected in the stacked images taken on each epoch.  Preliminary results of our observations are given below:\n\nDate       UT start      t-T0     Exp.    Filter  OT     Err.      UL    \n                     (mid, days)  (n*s)                         (3sigma)\n2025-09-19 21:40:39    3.42451    120*120   R     21.45  0.02     25.0\n2025-09-20 23:47:56    4.48374    78*120    R     21.89  0.03     24.7\n2025-09-21 22:21:48    5.44545    109*120   R     22.72  0.05     24.8\n\nPreliminary photometry is based on the nearby objects from PanSTARRS (magnitudes converted via Lupton 2005 transformations) and not corrected for the Galactic extinction.",
  "subject": "GRB 250916A: CrAO ZTSh R-band optical observations ",
  "bibcode": "2025GCN.41936....1P"
}