TITLE: GCN CIRCULAR NUMBER: 28731 SUBJECT: Swift GRB201021.85: Global MASTER-Net observations report DATE: 20/10/21 20:40:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) 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 GRB201021.85 (trigger No 1001130,00h 50m 12.00s , -55d 50m 20.4s, R=0.05) errorbox 73 sec after notice time and 295 sec after trigger time at 2020-10-21 20:32:14 UT, with upper limit up to 17.8 mag. The observations began at zenith distance = 26 deg. The sun altitude is -39.5 deg. The galactic latitude b = -62 deg., longitude l = 303 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1466597 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 325 | MASTER-SAAO | P/ | 60 | 17.7 | 325 | MASTER-SAAO | P\ | 60 | 17.8 | The observation and reduction will continue. The message may be cited.