Аннотация:MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210306A ( V. D’Elia et al., GCN 29597) errorbox 57322 sec after notice time and 57335 sec after trigger time at 2021-03-06 19:49:32 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 17 deg. The sun altitude is -42.8 deg. The galactic latitude b = 37 deg., longitude l = 157 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1562037 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_______________ ______|_____|_______|______|______ __ 30222 | MASTER- | C | 60 | 18.5 | 31162 | MASTER- | C | 60 | 18.4 | 32113 | MASTER- | C | 60 | 18.9 | 57426 | MASTER- Tavrida | C | 180 | 20.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.