TITLE:   GCN CIRCULAR
NUMBER:  41148
SUBJECT: Swift GRB 250725A: Global MASTER-Net observations report
DATE:    25/07/25 01:58:44 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 GRB250725.08 (trigger No 1336720,02h 21m 32.40s , -82d 47m 02.4s, R=0.05) errorbox  23 sec after notice time and 45 sec after trigger time at 2025-07-25 01:52:22 UT, with upper limit up to  18.3 mag. The observations began at zenith distance = 64 deg. The sun  altitude  is -50.5 deg. 

MASTER-SAAO robotic telescope  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB250725.08 errorbox  30 sec after notice time and 53 sec after trigger time at 2025-07-25 01:52:29 UT, with upper limit up to  17.0 mag. The observations began at zenith distance = 53 deg. The sun  altitude  is -46.5 deg. 

The galactic latitude b = -34 deg., longitude l = 300 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2947351

We obtain a following upper limits.  

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

      51 |         MASTER-OAFA |   C |    10 | 18.2 |        
      58 |         MASTER-SAAO |  P/ |    10 | 16.1 |        
      58 |         MASTER-SAAO | P\\ |    10 | 16.5 |        
      67 |         MASTER-OAFA |   C |    10 | 18.3 |        
      92 |         MASTER-SAAO |  P/ |    20 | 16.8 |        
      92 |         MASTER-SAAO | P\\ |    20 | 17.0 |        
Filter C is a clear (unfiltred) band. 


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