TITLE: GCN CIRCULAR NUMBER: 38762 SUBJECT: GRB 250101A: SAO RAS optical observations DATE: 25/01/01 19:20:35 GMT FROM: Moskvitin Alexander at SAO RAS <mosk@sao.ru> A. S. Moskvitin and O. I. Spiridonova (SAO RAS), report on behalf of the GRB follow-up team. We observed the field of Swift GRB 250101A (Page et al., GCN 38752) with the 1-m telescope of SAO RAS, Zeiss-1000 + CCD-photometer. On January 1, 16:18:20--16:51:10 UT (t_mid - T0 = 3.1986 hours) we obtained first set of 6 x 300 sec. images in Rc band. At 18:43:29--18:59:33 UT (t_mid - T0 = 5.4781 hours) we obtained second set of data, 3 x 300 sec. images in Rc band. The OT (Page et. al., GCN 38752; Li et al., GCN 38753; Mohan et al., GCN 38754; Zhu et al., GCN 38755, GCN 38759; Budnev et al., GCN 38756; WU et al., GCN 38758) is clearly detected in our stacked frames with the brightness of R = 19.76 +/- 0.01 (t_mid - T0 = 3.1986 hours) and R = 19.84 +/- 0.02 (5.4781 hours), calibrated against nearby PS1 stars (magnitudes were converted with the Lupton 2005 equations and not corrected for the MW extinction). Observations are ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/38762. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...