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GCN Circular 40734

Subject
Fermi trigger No 771718064: Global MASTER-Net observations report
Date
2025-06-15T22:15:32Z (6 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250615.92 (trigger No 771718064,08h 56m 28.80s , -44d 43m 48.0s, R=9.43) errorbox  119 sec after notice time and 154 sec after trigger time at 2025-06-15 22:10:13 UT, with upper limit up to  17.3 mag. The observations began at zenith distance = 83 deg. The sun  altitude  is -79.2 deg. 

The galactic latitude b =  1 deg., longitude l = 266 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2903453

We obtain a following upper limits.  

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

     170 | 2025-06-15 22:10:13 |         MASTER-SAAO | (09h 14m 46.22s , -47d 11m 07.1s) |   C |    30 | 17.0 |        
     170 | 2025-06-15 22:10:13 |         MASTER-SAAO | (09h 12m 12.28s , -46d 55m 37.8s) |   C |    30 | 15.0 |        
     224 | 2025-06-15 22:11:03 |         MASTER-SAAO | (09h 14m 46.07s , -47d 11m 01.9s) |   C |    40 | 17.3 |        
     224 | 2025-06-15 22:11:03 |         MASTER-SAAO | (09h 12m 12.19s , -46d 55m 31.5s) |   C |    40 | 15.1 |        
Filter C is a clear (unfiltred) band. 


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