Аннотация:AT2020kot During Fermi trigger 611605955 inspection by MASTER (Lipunov et al. GCN #27762 , https://master.sai.msu.ru/site/master2/observ.php?id=1360824 ) MASTER-SAAO auto-detection system ( Lipunov et al., “MASTER Global Robotic Net”, Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 19h 51m 17.88s +07d 59m 20.4s on 2020-05-20.04965 UT. The OT unfiltered magnitude is 16.3m at (mlim=19.1, MASTER-SAAO), also m_OT=16.4 at 2020-05-20 02:19:58UT (MASTER-IAC), and marginally seen with m We reobserved it at MASTER-Kislovodsk at 2020-05-20 22:00:56UT, that excluded OT from candidates to GRB (36%)counterpart .But It has fast decay now (MASTER is telescope): date_UT unfiltered_m_OT 2020-05-20 22:00:56 16.5 2020-05-20 22:00:56 16.5 2020-05-20 22:04:17 16.9 2020-05-20 22:04:17 16.9 We have reference image on 2016-08-11.79161 UT with unfiltered mlim= 19.1m.