{
  "subject": "GRB 251126A: Mondy and SAO RAS optical observations",
  "circularId": 42861,
  "eventId": "GRB 251126A",
  "submittedHow": "web",
  "bibcode": "2025GCN.42861....1V",
  "body": "A. Volnova (IKI), A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU, SAO RAS), E. Klunko (ISTP), V. S. Shergin (SAO RAS), N. Pankov (HSE, IKI), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:\n\nWe observed the field of the Swift GRB 251126A (Caputo et al., GCN 42843; Evans, GCN 42845; Goad et al., GCN 42851) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in R-band and the Zeiss-1000 1m telescope of the SAO RAS in Rc-band on November 26/27 night. Observations with the AZT-33IK started at 20:35:11 UT (1.4097 hours after the trigger), observations with the Zeiss-1000 started at 21:31:39 UT (2.3508 hours after the trigger).\n\nThe optical afterglow (Swain, GCN 42844; Fu et al., GCN  42848; Reguitti et al., GCN 42849; Broens et al., GCN 42850; Anguloet al., GCN 42855; Pulido-Torres et al; GCN 42856; Gupta et al., GCN 42857; Cotter et al., GCN 42858; Seki et al, GCN 42859) is clearly detected in individual frames. \nPreliminary photometry is given below.\n\nDate        UT start  t-T0       Exp.    Filter  OT     Err.  UL      Seeing\" Site/Instrum\n                     (mid,days)  (n*s)                       (3sigma)\n2025-11-26  20:35:11  0.06221    5*120   R       19.99  0.08  21.1    5.0     Mondy/AZT-33IK\n2025-11-26  20:45:12  0.07125    8*120   R       19.84  0.07  21.4    5.0     Mondy/AZT-33IK\n2025-11-26  21:01:12  0.08584   13*120   R       19.89  0.06  21.7    5.0     Mondy/AZT-33IK\n2025-11-26  21:31:39  0.10164    2*300   Rc      19.81  0.08  21.2    2.2     SAO/Zeiss-1000\n2025-11-26  21:58:22  0.12230    3*300   Rc      19.95  0.03  22.7    2.0     SAO/Zeiss-1000\n2025-11-27  01:14:02  0.25960    2*600   Rc      20.63  0.04  23.2    1.6     SAO/Zeiss-1000\n2025-11-27  01:57:56  0.29372    3*600   Rc      20.62  0.03  23.4    1.6     SAO/Zeiss-1000\n\nThe photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction.",
  "submitter": "Alina Volnova at IKI RAS <alinusss@gmail.com>",
  "createdOn": 1764250695216,
  "format": "text/plain"
}