TITLE: GCN CIRCULAR NUMBER: 41427 SUBJECT: Swift GRB 250818A: Global MASTER-Net observations report DATE: 25/08/19 05:30:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs lipunov@xray.sai.msu.ru
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), 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)
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 GRB 250818A ( S. B. Cenko et al., GCN 41403) errorbox 30 sec after notice time and 64 sec after trigger time at 2025-08-18 01:32:26 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 52 deg. The sun altitude is -43.8 deg.
The galactic latitude b = 3 deg., longitude l = 314 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2971328
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________
69 | MASTER-OAFA | C | 10 | 17.6 | 90 | MASTER-OAFA | C | 20 | 17.4 | 116 | MASTER-OAFA | C | 20 | 17.6 | 148 | MASTER-OAFA | C | 30 | 18.0 | 184 | MASTER-OAFA | C | 30 | 18.1 | 225 | MASTER-OAFA | C | 40 | 18.3 | 276 | MASTER-OAFA | C | 50 | 18.1 | 337 | MASTER-OAFA | C | 60 | 18.4 | 408 | MASTER-OAFA | C | 70 | 18.1 | 494 | MASTER-OAFA | C | 90 | 18.1 | 601 | MASTER-OAFA | C | 110 | 18.2 | 722 | MASTER-OAFA | C | 120 | 18.1 | 848 | MASTER-OAFA | C | 120 | 18.0 | 974 | MASTER-OAFA | C | 120 | 18.1 | 1100 | MASTER-OAFA | C | 120 | 18.1 | 1226 | MASTER-OAFA | C | 120 | 18.1 | 1352 | MASTER-OAFA | C | 120 | 18.1 | 1478 | MASTER-OAFA | C | 120 | 18.1 | 1604 | MASTER-OAFA | C | 120 | 18.0 | 1730 | MASTER-OAFA | C | 120 | 18.1 | 1856 | MASTER-OAFA | C | 120 | 18.3 | 1982 | MASTER-OAFA | C | 120 | 18.1 | 2108 | MASTER-OAFA | C | 120 | 18.1 | 2234 | MASTER-OAFA | C | 120 | 18.1 | 2361 | MASTER-OAFA | C | 120 | 18.0 | 2487 | MASTER-OAFA | C | 120 | 18.0 | 2613 | MASTER-OAFA | C | 120 | 17.9 | 2739 | MASTER-OAFA | C | 120 | 17.8 | 2865 | MASTER-OAFA | C | 120 | 17.9 | 2992 | MASTER-OAFA | C | 120 | 17.8 | 3118 | MASTER-OAFA | C | 120 | 17.9 | 3244 | MASTER-OAFA | C | 120 | 18.1 | 3370 | MASTER-OAFA | C | 120 | 18.1 | 3496 | MASTER-OAFA | C | 120 | 18.0 | 3622 | MASTER-OAFA | C | 120 | 18.1 | 3748 | MASTER-OAFA | C | 120 | 18.0 | 3874 | MASTER-OAFA | C | 120 | 18.1 | 4000 | MASTER-OAFA | C | 120 | 18.0 | 4126 | MASTER-OAFA | C | 120 | 18.0 | 4253 | MASTER-OAFA | C | 120 | 18.0 | 4379 | MASTER-OAFA | C | 120 | 18.1 | 4505 | MASTER-OAFA | C | 120 | 18.1 | 4631 | MASTER-OAFA | C | 120 | 17.9 | 4757 | MASTER-OAFA | C | 120 | 18.0 | 4884 | MASTER-OAFA | C | 120 | 18.0 | 5010 | MASTER-OAFA | C | 120 | 18.1 | 5135 | MASTER-OAFA | C | 120 | 18.0 | 5261 | MASTER-OAFA | C | 120 | 18.1 | 5388 | MASTER-OAFA | C | 120 | 18.1 | 5515 | MASTER-OAFA | C | 120 | 18.0 | 5640 | MASTER-OAFA | C | 120 | 18.0 | Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
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