{
  "eventId": "GRB 250924A",
  "submitter": "Alexander Moskvitin at SAO RAS <mosk@sao.ru>",
  "createdOn": 1758797607475,
  "submittedHow": "web",
  "body": "A. Moskvitin (SAO), V. Goranskij (SAI MSU), N. Pankov (HSE), \nA. Pozanenko (IKI) report on behalf of GRB follow-up collaboration \nand IKI-GRB-FuN.\n\nWe observed the field of the GRB 250924A (Siegel et. al, GCN 41897;\nOsborne et. al, GCN 41973; Campana et. al, GCN 41974) with two SAO RAS\ntelescopes, 1-m Zeiss-1000 equipped with the CCD-photometer on\nSeptember 24/25, 23:41:32--00:27:16, and 6-m BTA equipped \nwith the focal reducer SCORPIO-2 (Afanasiev & Moiseev,  2011, BaltA, \n20, 363) on September 25, 01:42:55--01:58:24 UT.\n\nThe optical transient (Siegel et. al, GCN 41959; Becerra et. al, \nGCN 41960; Schneider et. al, GCN 41963; Freeberg et. al, GCN 41968;\nPankov et. al, GCN 41969; Zheng and Filippenko, GCN 41970; \nSiegel, GCN 41975; Ma et al., GCN 41976; Cotter et al., GCN 41980; \nand also observed in NIR, Mo et. al, GCN 41972) is clearly detected \nin our stacked frames. Preliminary results are as following.\n\nDate       UTstart   Exptime   t-T0       Filter OT    Err.    UL  Tel.\n                     s         (mid, days)                (3sigma)\n2025.09.24 23:41:32  2520   0.65689       Rc  23.18 +/- 0.24  23.5 1-m\n2025.09.25 01:42:55  600    0.73068       Rc  23.07 +/- 0.10  24.3 6-m\n\nThe photometry calibrated against nearby USNO-B1.0 stars (R2 magnitudes)\nand not corrected for the Galactic extinction.",
  "circularId": 41981,
  "format": "text/plain",
  "subject": "GRB 250924A: SAO RAS optical observations",
  "bibcode": "2025GCN.41981....1M"
}