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GCN Circular 40722

Subject
Fermi trigger No 771494087: Global MASTER-Net observations report
Date
2025-06-13T18:16:25Z (21 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 GRB250613.33 (trigger No 771494087,17h 33m 19.92s , -38d 28m 01.2s, R=22.7) errorbox  32096 sec after notice time and 32128 sec after trigger time at 2025-06-13 16:50:10 UT, with upper limit up to  17.9 mag. Observations started at twilight.  The observations began at zenith distance = 60 deg. The sun  altitude  is -14.4 deg. 

The galactic latitude b = -3 deg., longitude l = 351 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2901954

We obtain a following upper limits.  

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

   32158 | 2025-06-13 16:50:10 |         MASTER-SAAO | (16h 41m 27.50s , -39d 04m 53.5s) |   C |    60 | 17.8 |        
   32158 | 2025-06-13 16:50:10 |         MASTER-SAAO | (16h 39m 08.66s , -38d 49m 46.2s) |   C |    60 | 17.8 |        
   32346 | 2025-06-13 16:53:18 |         MASTER-SAAO | (16h 41m 29.84s , -39d 04m 40.2s) |   C |    60 | 17.9 |        
   32346 | 2025-06-13 16:53:18 |         MASTER-SAAO | (16h 39m 10.94s , -38d 49m 34.3s) |   C |    60 | 17.9 |        
   32992 | 2025-06-13 17:04:04 |         MASTER-SAAO | (16h 41m 23.49s , -39d 06m 43.4s) |   C |    60 | 17.8 |        
   32992 | 2025-06-13 17:04:04 |         MASTER-SAAO | (16h 39m 05.20s , -38d 51m 34.7s) |   C |    60 | 17.8 |        
   33181 | 2025-06-13 17:07:13 |         MASTER-SAAO | (16h 41m 25.91s , -39d 05m 03.0s) |   C |    60 | 17.9 |        
   33181 | 2025-06-13 17:07:13 |         MASTER-SAAO | (16h 39m 07.41s , -38d 49m 54.4s) |   C |    60 | 17.9 |        
   33369 | 2025-06-13 17:10:21 |         MASTER-SAAO | (16h 41m 29.24s , -39d 04m 53.3s) |   C |    60 | 17.8 |        
   33369 | 2025-06-13 17:10:21 |         MASTER-SAAO | (16h 39m 10.68s , -38d 49m 45.2s) |   C |    60 | 17.8 |        
   33558 | 2025-06-13 17:13:30 |         MASTER-SAAO | (16h 41m 22.46s , -39d 04m 40.0s) |   C |    60 | 17.8 |        
   33558 | 2025-06-13 17:13:30 |         MASTER-SAAO | (16h 39m 03.78s , -38d 49m 32.6s) |   C |    60 | 17.8 |        
Filter C is a clear (unfiltred) band. 


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