TITLE: GCN CIRCULAR NUMBER: 41860 SUBJECT: GRB 250916A: MAO/AZT-22 optical observations DATE: 25/09/18 05:09:34 GMT FROM: Yodgor Rajabov at UBAI <rajabov@astrin.uz> O. Burkhonov, Y. Rajabov, B.Abidkhanov, S. Eghamberdiev, Y. Tillayev (UBAI), A. Shaymanov (Maidanak Observatory/UBAI) report on behalf of UBAI team. We observed the field of the GRB 250916A (Fermi GBM team, GCN 41839; Arya et al., GCN 41843; Cheung et al., GCN 41855) with the 1.5-m at Maidanak Observatory telescope AZT-22 equipped with the 4kx4k CCD SNUCAM camera(Im et al., 2010). We obtained series of 300 sec. images in Bessel R filter on September 17, 18:35:18-19:02:20 UTC. The OT (Belkin et al., GCN 41847; Mohan et al., GCN 41858, Moskvitin et al. GCN 41859) is clearly detected in the individual and stacked frames with the brightness of R = 19.76 +/- 0.03 (t_mid - T0 = 1.2229 days = 29.4917 hours). All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot catalog. For image template subrtaction we used PanSTARRS DR2 catalog. 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/41860. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...