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GCN Circular 40614

Subject
Swift GRB250603.05: Global MASTER-Net observations report
Date
2025-06-03T02:48:43Z (5 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-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 GRB250603.05 (trigger No 1320335,08h 39m 40.32s , -39d 16m 04.8s, R=0.05) errorbox  19 sec after notice time and 41 sec after trigger time at 2025-06-03 01:11:04 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 57 deg. The sun  altitude  is -44.5 deg. 

The galactic latitude b =  2 deg., longitude l = 260 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2890204

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      46 |         MASTER-OAFA |   C |    10 | 17.9 |        
      62 |         MASTER-OAFA |   C |    10 | 17.9 |        
      78 |         MASTER-OAFA |   C |    10 | 17.9 |        
      99 |         MASTER-OAFA |   C |    20 | 18.3 |        
     126 |         MASTER-OAFA |   C |    20 | 18.3 |        
     157 |         MASTER-OAFA |   C |    30 | 18.5 |        
     198 |         MASTER-OAFA |   C |    40 | 18.7 |        
     245 |         MASTER-OAFA |   C |    40 | 18.6 |        
     296 |         MASTER-OAFA |   C |    50 | 18.7 |        
     362 |         MASTER-OAFA |   C |    70 | 19.0 |        
     443 |         MASTER-OAFA |   C |    80 | 19.0 |        
     539 |         MASTER-OAFA |   C |   100 | 19.1 |        
     656 |         MASTER-OAFA |   C |   120 | 19.1 |        
     794 |         MASTER-OAFA |   C |   140 | 19.2 |        
     955 |         MASTER-OAFA |   C |   170 | 19.2 |        
    1138 |         MASTER-OAFA |   C |   180 | 19.2 |        
    1324 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1511 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1697 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1884 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2070 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2257 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2443 |         MASTER-OAFA |   C |   180 | 19.1 |        
Filter C is a clear (unfiltred) band. 


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