Fermi GRB 230911B: Global MASTER-Net observations report

MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230911B ( Fermi GBM team, GCN 34653) errorbox 928 sec after notice time and 961 sec after trigger time at 2023-09-11 04:41:51 UT, with upper limit up to 13.2 mag. The observations began at zenith distance = 24 deg. The sun altitude is -63.7 deg. The galactic latitude b = -59 deg., longitude l = 326 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2268866 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1052 | 2023-09-11 04:41:51 | MASTER-OAFA | (23h 25m 02.98s , -55d 03m 29.7s) | C | 180 | 12.1 | 1579 | 2023-09-11 04:50:38 | MASTER-OAFA | (23h 24m 58.92s , -55d 02m 04.7s) | C | 180 | 13.2 | 2059 | 2023-09-11 04:58:39 | MASTER-OAFA | (23h 25m 30.11s , -55d 04m 12.8s) | C | 180 | 13.1 | 2630 | 2023-09-11 05:08:09 | MASTER-OAFA | (23h 25m 03.23s , -55d 03m 59.3s) | C | 180 | 12.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.