TITLE: GCN CIRCULAR NUMBER: 32421 SUBJECT: Fermi GRB 220721A: Global MASTER-Net observations report DATE: 22/07/21 01:00:47 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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 (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (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 Fermi GRB 220721A ( Fermi GBM team, GCN 32420) errorbox 360 sec after notice time and 409 sec after trigger time at 2022-07-21 00:37:15 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 29 deg. The sun altitude is -62.5 deg. The galactic latitude b = -72 deg., longitude l = 346 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2036832 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 440 | 2022-07-21 00:37:15 | MASTER-SAAO | (00h 12m 27.53s , -33d 12m 32.0s) | C | 60 | 19.5 | 466 | 2022-07-21 00:37:41 | MASTER- | (00h 14m 27.09s , -30d 58m 08.1s) | C | 60 | 17.3 | 520 | 2022-07-21 00:38:35 | MASTER-SAAO | (00h 21m 56.34s , -33d 13m 09.2s) | C | 60 | 19.6 | 610 | 2022-07-21 00:40:05 | MASTER-SAAO | (00h 12m 48.29s , -35d 07m 04.3s) | C | 60 | 19.4 | 690 | 2022-07-21 00:41:25 | MASTER-SAAO | (00h 22m 30.15s , -35d 08m 07.7s) | C | 60 | 19.5 | 780 | 2022-07-21 00:42:55 | MASTER-SAAO | (00h 30m 35.98s , -33d 12m 29.3s) | C | 60 | 19.6 | 989 | 2022-07-21 00:46:23 | MASTER- | (23h 35m 25.55s , -35d 04m 35.1s) | C | 60 | 16.0 | 989 | 2022-07-21 00:46:24 | MASTER- | (23h 25m 57.69s , -34d 56m 37.5s) | C | 60 | 16.3 | 1122 | 2022-07-21 00:48:37 | MASTER- | (23h 58m 00.11s , -33d 05m 39.6s) | C | 60 | 15.3 | 1122 | 2022-07-21 00:48:37 | MASTER- | (23h 48m 44.79s , -32d 57m 41.4s) | C | 60 | 15.9 | 1151 | 2022-07-21 00:49:06 | MASTER-SAAO | (23h 35m 37.49s , -38d 53m 31.0s) | C | 60 | 19.5 | 1199 | 2022-07-21 00:49:54 | MASTER- | (23h 40m 23.19s , -33d 10m 30.2s) | C | 60 | 16.2 | 1199 | 2022-07-21 00:49:54 | MASTER- | (23h 31m 07.63s , -33d 02m 31.0s) | C | 60 | 16.5 | 1280 | 2022-07-21 00:51:15 | MASTER- | (23h 46m 29.29s , -31d 16m 47.4s) | C | 60 | 16.2 | 1280 | 2022-07-21 00:51:15 | MASTER- | (23h 37m 24.93s , -31d 08m 47.3s) | C | 60 | 16.6 | 1547 | 2022-07-21 00:55:42 | MASTER-SAAO | (00h 12m 25.62s , -33d 13m 54.3s) | C | 60 | 19.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.