TITLE: GCN CIRCULAR NUMBER: 31015 SUBJECT: Fermi GRB 211027A: Global MASTER-Net observations report DATE: 21/10/27 14:30:18 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, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, 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 (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 211027A ( Fermi GBM team, GCN 31012) errorbox 20879 sec after notice time and 20909 sec after trigger time at 2021-10-27 11:40:21 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 40 deg. The sun altitude is -17.7 deg. The galactic latitude b = 12 deg., longitude l = 48 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1767399 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 20939 | 2021-10-27 11:40:21 | MASTER-Tunka | (18h 36m 12.97s , +21d 29m 21.2s) | C | 60 | 17.8 | 21118 | 2021-10-27 11:43:20 | MASTER-Tunka | (18h 45m 24.29s , +18d 22m 36.6s) | C | 60 | 16.9 | Coadd 21186 | 2021-10-27 11:44:28 | MASTER-Tunka | (18h 29m 19.97s , +18d 24m 29.9s) | C | 60 | 17.6 | Coadd 21186 | 2021-10-27 11:44:28 | MASTER-Tunka | (18h 27m 33.61s , +19d 36m 05.7s) | C | 60 | 17.9 | Coadd 21420 | 2021-10-27 11:48:22 | MASTER-Tunka | (18h 24m 11.62s , +21d 29m 09.0s) | C | 60 | 16.6 | Coadd 21492 | 2021-10-27 11:49:34 | MASTER-Tunka | (18h 49m 34.73s , +16d 30m 18.6s) | C | 60 | 16.2 | Coadd 21565 | 2021-10-27 11:50:47 | MASTER-Tunka | (18h 23m 53.87s , +22d 11m 32.4s) | C | 60 | 16.6 | Coadd 21637 | 2021-10-27 11:51:59 | MASTER-Tunka | (18h 39m 17.95s , +14d 34m 17.0s) | C | 60 | 17.0 | Coadd 21710 | 2021-10-27 11:53:12 | MASTER-Tunka | (18h 39m 32.42s , +24d 04m 40.4s) | C | 60 | 17.6 | Coadd 21710 | 2021-10-27 11:53:12 | MASTER-Tunka | (18h 37m 44.64s , +25d 15m 57.9s) | C | 60 | 18.0 | Coadd 21918 | 2021-10-27 11:56:41 | MASTER-Tunka | (18h 38m 00.98s , +20d 18m 12.5s) | C | 60 | 16.8 | Coadd 21919 | 2021-10-27 11:56:41 | MASTER-Tunka | (18h 36m 14.32s , +21d 29m 31.3s) | C | 60 | 16.9 | Coadd 21987 | 2021-10-27 11:57:49 | MASTER-Tunka | (18h 46m 24.98s , +20d 17m 10.7s) | C | 60 | 17.0 | Coadd 21987 | 2021-10-27 11:57:49 | MASTER-Tunka | (18h 43m 32.47s , +19d 35m 27.7s) | C | 60 | 16.8 | Coadd 22214 | 2021-10-27 12:01:36 | MASTER-Tunka | (19h 01m 17.87s , +18d 21m 56.9s) | C | 60 | 16.5 | Coadd 22214 | 2021-10-27 12:01:36 | MASTER-Tunka | (18h 59m 32.63s , +19d 33m 15.7s) | C | 60 | 16.8 | Coadd 22286 | 2021-10-27 12:02:49 | MASTER-Tunka | (18h 40m 18.67s , +22d 10m 29.4s) | C | 60 | 16.4 | Coadd 22576 | 2021-10-27 12:07:38 | MASTER-Tunka | (18h 23m 48.64s , +22d 11m 05.2s) | C | 60 | 16.7 | Coadd 22779 | 2021-10-27 12:11:02 | MASTER-Tunka | (18h 58m 22.62s , +20d 15m 45.8s) | C | 60 | 17.3 | Coadd Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.