TITLE: GCN CIRCULAR NUMBER: 37229 SUBJECT: Fermi GRB 240821B: Global MASTER-Net observations report DATE: 24/08/22 12:31:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (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. Gress, N.M. Budnev, O.Ershova (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), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-Amur robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 240821B ( Fermi GBM team, GCN 37224) errorbox 53665 sec after notice time and 65775 sec after trigger time at 2024-08-22 11:33:51 UT, with upper limit up to 16.0 mag. Observations started at twilight. The observations began at zenith distance = 32 deg. The sun altitude is -9.3 deg. The galactic latitude b = 37 deg., longitude l = 114 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2570810 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 65805 | 2024-08-22 11:33:51 | MASTER-Amur | (15h 13m 11.66s , +77d 06m 51.0s) | C | 60 | 12.7 | 65805 | 2024-08-22 11:33:51 | MASTER-Amur | (14h 42m 26.03s , +76d 38m 06.4s) | C | 60 | 15.1 | 65898 | 2024-08-22 11:35:24 | MASTER-Amur | (15h 09m 25.36s , +78d 59m 07.7s) | C | 60 | 13.0 | 65898 | 2024-08-22 11:35:24 | MASTER-Amur | (14h 33m 33.70s , +78d 30m 39.3s) | C | 60 | 15.3 | 65991 | 2024-08-22 11:36:57 | MASTER-Amur | (14h 50m 06.17s , +74d 42m 34.8s) | C | 60 | 15.7 | 65991 | 2024-08-22 11:36:57 | MASTER-Amur | (15h 17m 09.50s , +75d 11m 42.5s) | C | 60 | 13.3 | 66085 | 2024-08-22 11:38:31 | MASTER-Amur | (15h 52m 12.28s , +78d 31m 05.4s) | C | 60 | 15.7 | 66085 | 2024-08-22 11:38:31 | MASTER-Amur | (16h 28m 08.08s , +78d 59m 38.0s) | C | 60 | 13.1 | 66178 | 2024-08-22 11:40:04 | MASTER-Amur | (16h 20m 38.07s , +77d 07m 10.6s) | C | 60 | 13.1 | 66178 | 2024-08-22 11:40:04 | MASTER-Amur | (15h 49m 53.21s , +76d 38m 54.1s) | C | 60 | 15.8 | 66270 | 2024-08-22 11:41:36 | MASTER-Amur | (16h 39m 23.25s , +80d 53m 11.4s) | C | 60 | 13.5 | 66270 | 2024-08-22 11:41:36 | MASTER-Amur | (15h 56m 43.41s , +80d 24m 33.7s) | C | 60 | 15.8 | 66364 | 2024-08-22 11:43:10 | MASTER-Amur | (15h 05m 16.23s , +80d 54m 24.1s) | C | 60 | 13.4 | 66364 | 2024-08-22 11:43:10 | MASTER-Amur | (14h 22m 16.41s , +80d 25m 09.5s) | C | 60 | 16.0 | 66457 | 2024-08-22 11:44:43 | MASTER-Amur | (16h 16m 06.05s , +75d 12m 34.0s) | C | 60 | 13.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.