TITLE: GCN CIRCULAR NUMBER: 31307 SUBJECT: Fermi GRB 211225C: Global MASTER-Net observations report DATE: 21/12/25 19:30:24 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 211225C ( Fermi GBM team, GCN 31306) errorbox 2856 sec after notice time and 2884 sec after trigger time at 2021-12-25 19:02:09 UT, with upper limit up to 17.1 mag. Observations started at twilight. The observations began at zenith distance = 71 deg. The sun altitude is -10.6 deg. The galactic latitude b = -51 deg., longitude l = 329 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1827113 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2915 | 2021-12-25 19:02:09 | MASTER-IAC | (21h 21m 59.02s , -29d 17m 33.3s) | C | 60 | 15.2 | 2915 | 2021-12-25 19:02:09 | MASTER-IAC | (21h 31m 16.29s , -29d 23m 28.3s) | C | 60 | 15.2 | 2995 | 2021-12-25 19:03:29 | MASTER-IAC | (21h 04m 29.50s , -29d 15m 44.4s) | C | 60 | 15.1 | 2995 | 2021-12-25 19:03:29 | MASTER-IAC | (21h 13m 46.67s , -29d 21m 39.8s) | C | 60 | 15.1 | 3075 | 2021-12-25 19:04:49 | MASTER-IAC | (21h 16m 21.79s , -27d 23m 23.3s) | C | 60 | 15.5 | 3075 | 2021-12-25 19:04:49 | MASTER-IAC | (21h 25m 29.34s , -27d 29m 18.0s) | C | 60 | 15.5 | 3155 | 2021-12-25 19:06:09 | MASTER-IAC | (21h 19m 59.12s , -33d 03m 55.7s) | C | 60 | 15.5 | 3155 | 2021-12-25 19:06:09 | MASTER-IAC | (21h 29m 39.18s , -33d 09m 51.5s) | C | 60 | 15.4 | 3255 | 2021-12-25 19:07:48 | MASTER-IAC | (21h 12m 13.12s , -33d 08m 33.6s) | C | 60 | 15.4 | 3255 | 2021-12-25 19:07:48 | MASTER-IAC | (21h 02m 31.80s , -33d 03m 18.3s) | C | 60 | 14.8 | 3334 | 2021-12-25 19:09:08 | MASTER-IAC | (21h 39m 19.77s , -31d 14m 06.6s) | C | 60 | 16.0 | 3334 | 2021-12-25 19:09:08 | MASTER-IAC | (21h 29m 50.78s , -31d 08m 47.3s) | C | 60 | 15.7 | 3414 | 2021-12-25 19:10:28 | MASTER-IAC | (21h 03m 53.96s , -31d 14m 34.2s) | C | 60 | 15.8 | 3414 | 2021-12-25 19:10:28 | MASTER-IAC | (20h 54m 24.49s , -31d 09m 17.6s) | C | 60 | 15.0 | 3494 | 2021-12-25 19:11:48 | MASTER-IAC | (21h 22m 26.34s , -35d 03m 57.5s) | C | 60 | 15.9 | 3494 | 2021-12-25 19:11:48 | MASTER-IAC | (21h 12m 31.71s , -34d 58m 42.8s) | C | 60 | 15.4 | 3574 | 2021-12-25 19:13:08 | MASTER-IAC | (21h 09m 09.61s , -27d 27m 29.3s) | C | 60 | 16.6 | 3574 | 2021-12-25 19:13:08 | MASTER-IAC | (21h 00m 01.03s , -27d 22m 08.4s) | C | 60 | 15.8 | 3654 | 2021-12-25 19:14:28 | MASTER-IAC | (21h 43m 21.35s , -27d 26m 40.9s) | C | 60 | 17.1 | 3654 | 2021-12-25 19:14:28 | MASTER-IAC | (21h 34m 12.97s , -27d 21m 19.4s) | C | 60 | 16.6 | 3734 | 2021-12-25 19:15:48 | MASTER-IAC | (21h 41m 02.66s , -35d 03m 53.9s) | C | 60 | 16.6 | 3734 | 2021-12-25 19:15:48 | MASTER-IAC | (21h 31m 08.14s , -34d 58m 38.3s) | C | 60 | 16.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.