TITLE: GCN CIRCULAR NUMBER: 39119 SUBJECT: Swift GRB250129A: MASTER 4 days observations report DATE: 25/02/02 03:23:05 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs lipunov@xray.sai.msu.ru

V.Lipunov, E.Gorbovskoy, A.Kuznetsov, N.Tiurina, P.Balanutsa, I.Panchenko, K.Zhirkov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, Ya.Kechin, V.Senik, V.Topolev, A.Chasovnikov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), D.Buckley (SAAO), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)

The MASTER-OAFA All Sky Camera located in Argentina (OAFA observatory of San Juan National University) imaged SWIFT GRB 250129A (A. P. Beardmore et al., GCN 39066) errorbox with upper limit up to ~8 mag (V) at single 5-s images with _prompt_ limit ~10 mag.

MASTER-OAFA Very Wide Field Camera (VWFC, MASTER-ShOK camera of Global MASTER-Net: http://observ.pereplet.ru, Lipunov, Korniov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 626 pp.) located in Argentina (OAFA observatory of San Juan National University) was pointed to the SWIFT GRB 250129A ( A. P. Beardmore et al., GCN 39066) errorbox 185 sec after trigger time at 2025-01-29 04:48:14 UT, with upper limit up to ~15 mag.

MASTER500-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru) located in Argentina (OAFA observatory of San Juan National University) was pointed to the SWIFT GRB 250129A (Francile et al., GCN 39065) errorbox 160 sec after notice time (240sec after trigger time) at 2025-01-29 04:49:09 UT, with upper limit up to 21.1 mag.

The observations began at zenith distance = 73 deg. (the sun altitude was -41.0 deg.) and were condinued at 30, 31 Jan, 01, 02, 03 Feb.

MASTER600-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the SWIFT GRB 250129A errorbox 40114 sec after notice time (40194 sec after trigger time) at 2025-01-29 15:55:03 UT, with upper limit up to 21.0 mag. The observations began at zenith distance = 85 deg (the sun altitude was -52.8 deg.) and were continued at 30, 31 Jan, 01, 02 Feb 2025.

MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the SWIFT GRB 250129A errorbox 55139 sec after notice time (55220 sec after trigger time) at 2025-01-29 20:05:29 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 83 deg. The sun altitude was -59.8 deg. Observations were continued observations at 30, 31 Jan, 01, 02 Jan.

MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) was pointed to the SWIFT GRB 250129A errorbox 62515 sec after notice time (62595 sec after trigger time) at 2025-01-29 22:08:24 UT, with upper limit up to 20.2 mag. The observations began at zenith distance = 81 deg. The sun altitude is -39.2 deg.

MASTER OT J131442.41+050150.4 presents from 29 jan (240s after trigger time) up to now (~21.5m, unfiltered) all 4 days with light curve with complicated structure .

The galactic latitude b = 67 deg., longitude l = 319 deg.

Real time updated cover map and discovered OT are available here: https://master.sai.msu.ru/site/master2/observ.php?id=2760136

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