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GCN Circular 40781

Subject
Fermi GRB 250617A: Global MASTER-Net observations report
Date
2025-06-18T22:15:43Z (3 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-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250617A ( Fermi GBM team, GCN 40758Loading...
 
 ) errorbox  1 days 17814 sec after notice time and 1 days 17823 sec after trigger time at 2025-06-18 21:06:16 UT, with upper limit up to  17.7 mag. The observations began at zenith distance = 66 deg. The sun  altitude  is -23.6 deg. 

The galactic latitude b = -25 deg., longitude l = 107 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2905762

We obtain a following upper limits.  

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

  104253 | 2025-06-18 21:06:16 |   MASTER-Kislovodsk | (23h 40m 51.75s , +35d 31m 02.8s) |   C |    60 | 17.7 |        
  104540 | 2025-06-18 21:11:02 |   MASTER-Kislovodsk | (23h 27m 52.38s , +37d 23m 28.9s) |   C |    60 | 16.0 |        
  104624 | 2025-06-18 21:12:26 |   MASTER-Kislovodsk | (23h 37m 52.75s , +37d 24m 33.4s) |   C |    60 | 16.3 |        
  104845 | 2025-06-18 21:16:08 |   MASTER-Kislovodsk | (23h 46m 54.05s , +37d 24m 18.0s) |   C |    60 | 17.3 |        
  104928 | 2025-06-18 21:17:31 |   MASTER-Kislovodsk | (23h 57m 02.84s , +37d 22m 47.1s) |   C |    60 | 16.6 |        
  105010 | 2025-06-18 21:18:53 |   MASTER-Kislovodsk | (23h 40m 51.77s , +35d 28m 47.9s) |   C |    60 | 17.1 |        
Filter C is a clear (unfiltred) band. 


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