TITLE: GCN CIRCULAR NUMBER: 35417 SUBJECT: LAT GRB231222.31: Global MASTER-Net observations report DATE: 23/12/22 21:55:52 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs lipunov@xray.sai.msu.ru

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (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. Gress, N.M. Budnev, O.Ershova (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),

V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)

MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the LAT GRB231222.31 (trigger No 724922767,16h 45m 24.00s , +19d 30m 00.0s, R=0.299833) errorbox 9379 sec after notice time and 49215 sec after trigger time at 2023-12-22 21:06:17 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 81 deg. The sun altitude is -36.5 deg.

The galactic latitude b = 36 deg., longitude l = 38 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2340436

We obtain a following upper limits.

Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________

49278 | 2023-12-22 21:06:17 | MASTER-Tunka | (16h 44m 15.30s , +19d 23m 06.7s) | C | 125 | 14.8 | 51473 | 2023-12-22 21:42:45 | MASTER-Tunka | (16h 44m 16.33s , +19d 24m 26.0s) | C | 140 | 15.2 | 51624 | 2023-12-22 21:45:16 | MASTER-Tunka | (16h 44m 22.24s , +19d 23m 36.0s) | C | 140 | 18.1 | 51733 | 2023-12-22 21:47:50 | MASTER-Tunka | (16h 44m 17.59s , +19d 22m 40.5s) | C | 50 | 17.4 | 51781 | 2023-12-22 21:47:50 | MASTER-Tunka | (16h 44m 17.59s , +19d 22m 40.4s) | C | 145 | 18.1 | Coadd 51794 | 2023-12-22 21:48:50 | MASTER-Tunka | (16h 44m 22.74s , +19d 22m 52.8s) | C | 50 | 17.5 | 51851 | 2023-12-22 21:49:50 | MASTER-Tunka | (16h 44m 20.66s , +19d 24m 35.0s) | C | 45 | 17.5 | 51908 | 2023-12-22 21:50:47 | MASTER-Tunka | (16h 44m 20.65s , +19d 23m 01.1s) | C | 45 | 17.5 | Filter C is a clear (unfiltred) band.

The observation and reduction will continue. The message may be cited.

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