TITLE: GCN CIRCULAR NUMBER: 45339 SUBJECT: GRB260809A: MAO/AZT-22 optical observations DATE: 26/08/10 04:16:25 GMT FROM: Yodgor Rajabov at UBAI <rajabov@astrin.uz> Y. Rajabov, O. Burkhonov, B.Abidkhanov, S. Ehgamberdiev, Y. Tillayev (UBAI), A. Shaymanov, T. Boyqobilov (Maidanak Observatory/UBAI) report on behalf of UBAI team. We observed the field of GRB 260809A detected by SVOM (Brunet et al., GCN 45331) with the AZT-22 1.5m telescope of the Maidanak Observatory (MAO) starting on 2026-08-09 at 22:25:45 UT, i.e, ~7.47 hours after the SVOM/ECLAIRs trigger. In total we obtained 4x300 s exposures in the R-band using 4kx4k CCD SNUCAM camera (Im et al., 2010). We detect the afterglow in our stacked frame at the position reported by Li et al. (GCN 45336). Our preliminary measurements consist with detections reported by Li et al. GCN 45336 and Adami et. al. GCN 45338. Preliminary photometry is as follows: Date UTstart Exptime t-T0 Filter OT Err. UL SNR Site/Telescope (nxs) (mid, hours) 2026-08-09 22:25:45 4x300 7.47 R 22.97 0.1 23.24 6 MAO/AZT-22 All the data have been reduced by a single data processing pipeline, STDWeb (Karpov 2025). Images obtained in Johnson Cousins filters were calibrated using the Gaia DR3 Synphot catalog. Our measurements in Vega magnitude system and the data has not corrected for the Galactic extinction. Maidanak astronomical observatory (MAO) is an observational facility of the Ulugh Beg Astronomical Institute (UBAI), Uzbekistan Academy of Sciences (http://maidanak.uz/). View this GCN Circular online at https://gcn.nasa.gov/circulars/45339. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...