Swift GRB 250103B: Global MASTER-Net observations report

MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 250103B ( R. A. J. Eyles-Ferris et al., GCN 38796) errorbox 10372 sec after notice time and 10451 sec after trigger time at 2025-01-03 18:38:29 UT, with upper limit up to 18.0 mag. Observations started at twilight. The observations began at zenith distance = 10 deg. The sun altitude is -9.9 deg. The galactic latitude b = -53 deg., longitude l = 234 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2732251 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 10542 | MASTER-SAAO | C | 180 | 18.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.