TITLE: GCN CIRCULAR NUMBER: 31292 SUBJECT: Fermi GRB 211223B: Global MASTER-Net observations report DATE: 21/12/23 23:00:25 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), B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez, M.L.H.Rodriguez (INAOE, OAGH) A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (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 211223B ( Fermi GBM team, GCN 31287) errorbox 48951 sec after notice time and 48978 sec after trigger time at 2021-12-23 21:59:40 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 81 deg. The sun altitude is -48.9 deg. The galactic latitude b = 14 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=1824738 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 49008 | 2021-12-23 21:59:40 | MASTER-IAC | (19h 50m 57.14s , +48d 39m 52.2s) | C | 60 | 16.5 | 49088 | 2021-12-23 22:01:00 | MASTER-IAC | (19h 52m 29.69s , +46d 44m 47.5s) | C | 60 | 16.1 | 49935 | 2021-12-23 22:15:07 | MASTER-IAC | (19h 50m 58.21s , +48d 38m 53.4s) | C | 60 | 16.0 | 50016 | 2021-12-23 22:16:27 | MASTER-IAC | (19h 52m 32.18s , +46d 46m 10.9s) | C | 60 | 15.7 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.