TITLE: GCN CIRCULAR NUMBER: 30327 SUBJECT: Fermi GRB 210626A: Global MASTER-Net observations report DATE: 21/06/26 21:16:42 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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210626A ( Fermi GBM team, GCN 30323) errorbox 45371 sec after notice time and 45494 sec after trigger time at 2021-06-26 20:54:30 UT, with upper limit up to 18.5 mag. Observations started at twilight. The observations began at zenith distance = 33 deg. The sun altitude is -10.6 deg. The galactic latitude b = 51 deg., longitude l = 343 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1645256 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 45524 | 2021-06-26 20:54:30 | MASTER-IAC | (14h 31m 35.31s , -04d 23m 21.9s) | C | 60 | 17.3 | 45524 | 2021-06-26 20:54:30 | MASTER-IAC | (14h 23m 30.29s , -04d 17m 54.2s) | C | 60 | 16.8 | 45604 | 2021-06-26 20:55:49 | MASTER-IAC | (14h 29m 54.51s , -02d 30m 25.6s) | C | 60 | 17.3 | 45604 | 2021-06-26 20:55:49 | MASTER-IAC | (14h 21m 50.29s , -02d 24m 57.4s) | C | 60 | 17.1 | 45684 | 2021-06-26 20:57:09 | MASTER-IAC | (14h 19m 03.53s , -06d 19m 19.7s) | C | 60 | 17.5 | 45684 | 2021-06-26 20:57:09 | MASTER-IAC | (14h 10m 57.01s , -06d 13m 53.3s) | C | 60 | 17.3 | 45763 | 2021-06-26 20:58:29 | MASTER-IAC | (14h 16m 27.27s , -04d 25m 15.0s) | C | 60 | 17.6 | 45763 | 2021-06-26 20:58:29 | MASTER-IAC | (14h 08m 22.21s , -04d 19m 48.0s) | C | 60 | 17.5 | 45843 | 2021-06-26 20:59:49 | MASTER-IAC | (14h 34m 23.49s , -06d 17m 53.6s) | C | 60 | 17.7 | 45843 | 2021-06-26 20:59:49 | MASTER-IAC | (14h 26m 16.98s , -06d 12m 26.1s) | C | 60 | 17.5 | 45924 | 2021-06-26 21:01:09 | MASTER-IAC | (14h 29m 01.44s , -00d 37m 28.8s) | C | 60 | 18.1 | 45924 | 2021-06-26 21:01:09 | MASTER-IAC | (14h 20m 57.52s , -00d 32m 00.3s) | C | 60 | 17.9 | 46004 | 2021-06-26 21:02:30 | MASTER-IAC | (14h 14m 40.67s , -02d 29m 37.6s) | C | 60 | 18.1 | 46004 | 2021-06-26 21:02:30 | MASTER-IAC | (14h 06m 36.35s , -02d 24m 10.3s) | C | 60 | 17.5 | 46084 | 2021-06-26 21:03:50 | MASTER-IAC | (14h 22m 43.90s , -08d 12m 29.4s) | C | 60 | 17.9 | 46084 | 2021-06-26 21:03:50 | MASTER-IAC | (14h 14m 35.23s , -08d 07m 03.1s) | C | 60 | 17.7 | 46164 | 2021-06-26 21:05:10 | MASTER-IAC | (14h 13m 45.82s , -00d 35m 27.8s) | C | 60 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.