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GCN Circular 40601

Subject
Fermi trigger No 770470765: Global MASTER-Net observations report
Date
2025-06-02T00:48:11Z (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 GRB250601.49 (trigger No 770470765,03h 02m 00.00s , -51d 57m 00.0s, R=11.63) errorbox  43681 sec after notice time and 43715 sec after trigger time at 2025-06-01 23:47:55 UT, with upper limit up to  19.0 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -71.3 deg. 

The galactic latitude b = -55 deg., longitude l = 267 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2888592

We obtain a following upper limits.  

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

   43745 | 2025-06-01 23:47:55 |         MASTER-SAAO | (01h 44m 18.74s , -52d 18m 33.7s) |   C |    60 | 16.4 |        
   43745 | 2025-06-01 23:47:55 |         MASTER-SAAO | (01h 41m 30.62s , -52d 03m 14.0s) |   C |    60 | 18.7 |        
   44762 | 2025-06-02 00:04:51 |         MASTER-SAAO | (01h 44m 12.09s , -52d 18m 24.7s) |   C |    60 | 16.8 |        
   44762 | 2025-06-02 00:04:51 |         MASTER-SAAO | (01h 41m 22.46s , -52d 02m 58.5s) |   C |    60 | 18.8 |        
   45994 | 2025-06-02 00:25:24 |         MASTER-SAAO | (01h 44m 18.84s , -52d 18m 56.3s) |   C |    60 | 17.2 |        
   45994 | 2025-06-02 00:25:24 |         MASTER-SAAO | (01h 41m 28.06s , -52d 03m 32.4s) |   C |    60 | 19.0 |        
Filter C is a clear (unfiltred) band. 


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