TITLE: GCN CIRCULAR NUMBER: 34120 SUBJECT: Fermi GRB 230628C: Global MASTER-Net observations report DATE: 23/06/29 11:30:37 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, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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), 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), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-OAGH robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 230628C ( Fermi GBM team, GCN 34106) errorbox 61791 sec after notice time and 61823 sec after trigger time at 2023-06-29 10:46:57 UT, with upper limit up to 17.1 mag. Observations started at twilight. The observations began at zenith distance = 27 deg. The sun altitude is -16.8 deg. The galactic latitude b = 2 deg., longitude l = 73 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2229961 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 61913 | 2023-06-29 10:46:57 | MASTER-OAGH | (19h 47m 59.92s , +37d 05m 18.1s) | C | 180 | 17.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.