TITLE: GCN CIRCULAR NUMBER: 26590 SUBJECT: Swift GRB191226.25: Global MASTER-Net observations report DATE: 19/12/26 06:54:11 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB191226.25 (trigger No 946256,09h 03m 26.76s , -40d 17m 50.3s, R=0.05) errorbox 18 sec after notice time and 100 sec after trigger time at 2019-12-26 05:54:44 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 19 deg. The sun altitude is -32.4 deg. The galactic latitude b = 4 deg., longitude l = 263 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1240203 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 111 | MASTER-OAFA | C | 20 | 18.1 | 167 | MASTER-OAFA | C | 30 | 18.4 | 235 | MASTER-OAFA | C | 40 | 18.5 | 311 | MASTER-OAFA | C | 50 | 18.7 | 403 | MASTER-OAFA | C | 70 | 18.8 | 514 | MASTER-OAFA | C | 90 | 19.0 | 645 | MASTER-OAFA | C | 110 | 19.1 | 802 | MASTER-OAFA | C | 140 | 19.2 | 993 | MASTER-OAFA | C | 180 | 19.3 | 1204 | MASTER-OAFA | C | 180 | 19.3 | 1416 | MASTER-OAFA | C | 180 | 19.3 | 1627 | MASTER-OAFA | C | 180 | 19.3 | 1838 | MASTER-OAFA | C | 180 | 19.3 | 2049 | MASTER-OAFA | C | 180 | 19.2 | 2260 | MASTER-OAFA | C | 180 | 19.3 | 2471 | MASTER-OAFA | C | 180 | 19.3 | 2682 | MASTER-OAFA | C | 180 | 19.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.