TITLE: GCN CIRCULAR NUMBER: 27611 SUBJECT: IceCube Alert 200420.97: Global MASTER-Net observations report DATE: 20/04/21 01:39:15 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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) started inspect of the IceCube Alert 200420.97 (trigger No 200410,16h 10m 19.20s , +11d 36m 36.0s, R=14.05) errorbox 9 days 14340 sec after notice time and 4703 sec after trigger time at 2020-04-21 00:38:18 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 44 deg. The sun altitude is -55.7 deg. The galactic latitude b = 40 deg., longitude l = 25 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1334559 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 4793 | 2020-04-21 00:38:18 | MASTER-SAAO | (16h 09m 13.68s , +11d 38m 43.2s) | C | 180 | 16.8 | 6553 | 2020-04-21 01:07:38 | MASTER-SAAO | (16h 12m 33.63s , +11d 39m 58.9s) | C | 180 | 20.0 | 6559 | 2020-04-21 01:07:44 | MASTER-SAAO | (16h 05m 24.75s , +11d 38m 56.1s) | C | 180 | 16.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.