{
  "submittedHow": "web",
  "body": "A. S. Moskvitin, O. I. Spiridonova, V. V. Vlasyuk (SAO RAS), \nN. Pankov (HSE, IKI), A. Pozanenko (IKI), A. Ghosh, S. Razzaque \n(CAPP, University of Johannesburg), Tao An and Yuanqi Liu \n(Shanghai Astronomical Observatory) report on behalf of GRB follow-up \ncollaboration and IKI-GRB-FuN.\n\nWe observed the field of the GRB 251013C (The Fermi GBM team, \nGCN 42221; Rakotondrainibe et al., GCN 42222) with the 1-m SAO RAS \ntelescope Zeiss-1000 equipped with the CCD-photometer.\nThe observations started on 2025.10.13T19:47:54 UT \n(t_mid - T0 = 2.1369 hours).\n\nThe OT (Palmerio et al., GCN 42223; Perez-Garcia et al., GCN 42225; \nKonno et al., GCN 42226; Martin-Carrillo et al., GCN 42227; Masi, \nGCN 42228; Palmerio et al, GCN 42229) is clearly detected \nin the individual images with the following brightness.\n\nDate        UT start  t-T0     Exp.  Filter  OT     Err. \n                      (mid, d) (s)    \n2025.10.13  19:47:54  0.09078  300   Rc      15.84 +/- 0.01\n2025.10.13  20:04:02  0.10082  100   Rc      16.05 +/- 0.01\n2025.10.13  20:15:34  0.10883  100   Rc      16.21 +/- 0.01\n\nPreliminary photometry is based on the nearby SDSS objects\n(magnitudes converted with Lupton 2005 equations)\nand has not corrected for the Galactic extinction.\n\nThe observations with the 1-m telescope in BVRI filters\nand also with the 0.5-m telescope AS-500/2 are ongoing.",
  "circularId": 42230,
  "createdOn": 1760391100046,
  "version": 2,
  "format": "text/plain",
  "editedBy": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Alexander Moskvitin at SAO RAS <mosk@sao.ru>",
  "eventId": "GRB 251013C",
  "bibcode": "2025GCN.42230....1M",
  "subject": "GRB 251013C: SAO RAS optical observations",
  "editedOn": 1761168693528,
  "submitter": "Alexander Moskvitin at SAO RAS <mosk@sao.ru>"
}