TITLE: GCN CIRCULAR NUMBER: 46263 SUBJECT: GRB 261113A: Mondy and AbAO optical observations DATE: 26/11/14 06:17:27 GMT FROM: Alexander Moskvitin at SAO RAS A. Moskvitin (SAO), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. Volnova (IKI), N. Pankov (IKI), O. Spiridonova (SAO) report on behalf of IKI-GRB-FuN and SAO GRB follow-up team. We observed the field of the GRB 261113A (Saccardi et al., GCN 46244) at the redshift of z = 3.580 (Saccardi et al., GCN 46261) with the 1.5-m telescope AZT-33IK of Sayan Solar Observatory (Mondy) and AS-32 telescope of Abastumani Observatory (AbAO) started (UT) 2026-11-13T15:06:44 and 2026-11-13T17:37:43 respectively. The OT (Lei et al., GCN 46248; Li et al., GCN 46249; Yin et al., GCN 46250; Chen et al., GCN 46251; Wu et al., GCN 46252; Zhao et al., GCN 46253; Li et al., GCN 46254; Saikia et al., GCN 46256; Adami et al., GCN 46257; Gress et al., GCN 46258; Izzo et al., GCN 46259; Saccardi et al., GCN 46261; Maksut et al., GCN 46262; also observed in NIR: Lin et al., GCN 46247; Brivio et al., GCN 46260) is clearly detected in our stacked images. The results of some stacked epochs are as follows. Date UT start t-T0 Exp, Filter Obj Err UL Telescope (mid,h) (n*s) (3sigma) 2026-11-13T15:06:44 0.67833 10*60 R 19.04 +/- 0.02 22.1 AZT-33IK 2026-11-13T15:26:45 1.01208 10*60 R 19.18 +/- 0.04 21.6 AZT-33IK 2026-11-13T15:46:56 1.34847 10*60 R 19.35 +/- 0.03 22.0 AZT-33IK 2026-11-13T16:09:31 1.72486 10*60 R 19.50 +/- 0.04 22.0 AZT-33IK 2026-11-13T16:29:33 2.06708 10*60 R 19.76 +/- 0.13 20.9 AZT-33IK 2026-11-13T16:50:35 2.40931 10*60 R 19.75 +/- 0.05 22.0 AZT-33IK 2026-11-13T17:37:43 3.63917 40*60 R 20.48 +/- 0.17 21.3 AS-32 This preliminary photometry (Vega) is based on nearby SDSS stars (Lupton 2005 transformation) and not corrected for Galactic extinction. Based on our data, it can be suggested that there is a jet break in the light curve, occurring between 3 and 4 hours after the onset of the burst.