TITLE: GCN CIRCULAR NUMBER: 30532 SUBJECT: Fermi trigger No 649072251: Global MASTER-Net observations report DATE: 21/07/27 12:30:29 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB210727.41 (trigger No 649072251,12h 42m 52.80s , -59d 10m 48.0s, R=1.89) errorbox 131 sec after notice time and 174 sec after trigger time at 2021-07-27 09:53:41 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 86 deg. The sun altitude is -19.6 deg. The galactic latitude b = 3 deg., longitude l = 302 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1671621 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 189 | 2021-07-27 09:53:41 | MASTER-OAFA | (12h 31m 52.86s , -61d 34m 12.7s) | C | 30 | 15.9 | 269 | 2021-07-27 09:53:41 | MASTER-OAFA | (12h 31m 52.83s , -61d 34m 13.0s) | C | 190 | 16.5 | Coadd 255 | 2021-07-27 09:54:41 | MASTER-OAFA | (12h 31m 42.42s , -60d 14m 32.3s) | C | 40 | 15.6 | 335 | 2021-07-27 09:55:51 | MASTER-OAFA | (12h 31m 46.13s , -61d 34m 16.0s) | C | 60 | 16.2 | 433 | 2021-07-27 09:57:24 | MASTER-OAFA | (12h 31m 48.14s , -60d 14m 37.1s) | C | 70 | 15.8 | 549 | 2021-07-27 09:59:05 | MASTER-OAFA | (12h 31m 46.65s , -61d 36m 27.0s) | C | 100 | 16.3 | 855 | 2021-07-27 10:03:46 | MASTER-OAFA | (12h 41m 32.17s , -59d 42m 02.7s) | C | 150 | 16.2 | 1265 | 2021-07-27 10:10:21 | MASTER-OAFA | (12h 41m 35.26s , -59d 43m 01.2s) | C | 180 | 16.4 | 1476 | 2021-07-27 10:13:52 | MASTER-OAFA | (12h 41m 27.10s , -58d 20m 51.6s) | C | 180 | 15.2 | 1686 | 2021-07-27 10:17:22 | MASTER-OAFA | (12h 41m 29.01s , -59d 42m 56.2s) | C | 180 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.