TITLE: GCN CIRCULAR NUMBER: 30496 SUBJECT: Swift GRB210724.84: Global MASTER-Net observations report DATE: 21/07/24 20:34:20 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 GRB210724.84 (trigger No 1061482,15h 09m 37.68s , -06d 16m 26.4s, R=0.05) errorbox 21 sec after notice time and 566 sec after trigger time at 2021-07-24 20:23:35 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 46 deg. The sun altitude is -56.0 deg. MASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB210724.84 errorbox 28 sec after notice time and 573 sec after trigger time at 2021-07-24 20:23:42 UT, with upper limit up to 15.3 mag. The observations began at zenith distance = 71 deg. The sun altitude is -23.3 deg. The galactic latitude b = 42 deg., longitude l = 354 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1669395 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 621 | MASTER-SAAO | P\ | 110 | 17.1 | 629 | MASTER-Tavrida | P\ | 110 | 15.3 | 758 | MASTER-SAAO | P\ | 140 | 17.2 | 773 | MASTER-Tavrida | P\ | 140 | 15.3 | The observation and reduction will continue. The message may be cited.