Аннотация:MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the Swift GRB210402.92 (trigger No 1040123,13h 13m 01.92s , +44d 30m 46.8s, R=0.00130556) errorbox 108 sec after trigger time at 2021-04-02 22:07:40 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 42 deg. The sun altitude is -35.7 deg. MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB210402.92 errorbox 123 sec after trigger time at 2021-04-02 22:07:55 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 0 deg. The sun altitude is -40.6 deg. The galactic latitude b = 72 deg., longitude l = 109 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1582249 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_______________ ______|_____|_______|______|______ __ 139 | MASTER-IAC | C | 60 | 19.1 | 154 | MASTER-Tavrida | C | 60 | 18.8 | 292 | MASTER-IAC | P| | 50 | 18.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.