TITLE: GCN CIRCULAR NUMBER: 40156 SUBJECT: EP250416a: Global MASTER-Net observations report DATE: 25/04/17 05:18:32 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs lipunov@xray.sai.msu.ru

V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, 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. 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 EP250416a ( EP Team et al., GCN 40154) errorbox 3581 sec after notice time and 37096 sec after trigger time at 2025-04-17 04:12:15 UT, with upper limit up to 18.2 mag. The observations began at zenith distance = 79 deg. The sun altitude is -68.8 deg.

The galactic latitude b = 33 deg., longitude l = 47 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2845513

We obtain a following upper limits.

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

37127 | 2025-04-17 04:12:15 | MASTER-OAFA | (17h 05m 52.87s , +25d 40m 55.7s) | C | 60 | 16.5 | 37187 | 2025-04-17 04:12:15 | MASTER-OAFA | (17h 05m 52.85s , +25d 40m 55.5s) | C | 180 | 17.7 | Coadd 37590 | 2025-04-17 04:19:58 | MASTER-OAFA | (17h 05m 56.72s , +25d 41m 13.9s) | C | 60 | 17.3 | 38093 | 2025-04-17 04:28:21 | MASTER-OAFA | (17h 06m 00.04s , +25d 40m 57.5s) | C | 60 | 17.5 | 38511 | 2025-04-17 04:35:20 | MASTER-OAFA | (17h 05m 58.06s , +25d 40m 40.2s) | C | 60 | 17.7 | 39442 | 2025-04-17 04:50:50 | MASTER-OAFA | (17h 06m 00.53s , +25d 42m 42.8s) | C | 60 | 18.2 | Filter C is a clear (unfiltred) band.

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

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