TITLE:   GCN CIRCULAR
NUMBER:  40818
SUBJECT: Fermi GRB 250624A: Global MASTER-Net observations report
DATE:    25/06/24 20:30:25 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-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 250624A ( Fermi GBM team, GCN 40817) errorbox  542 sec after notice time and 573 sec after trigger time at 2025-06-24 19:45:55 UT, with upper limit up to  14.4 mag. Observations started at twilight.  The observations began at zenith distance = 57 deg. The sun  altitude  is -8.0 deg. 

The galactic latitude b = -46 deg., longitude l = 121 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2915767

We obtain a following upper limits.  

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

     574 | 2025-06-24 19:45:55 |        MASTER-Tunka | (00h 36m 20.26s , +16d 05m 54.9s) |   C |     1 | 14.4 |        
     584 | 2025-06-24 19:46:05 |        MASTER-Tunka | (00h 36m 20.23s , +16d 05m 54.7s) |   C |     1 | 14.4 |        
     590 | 2025-06-24 19:46:10 |        MASTER-Tunka | (00h 36m 20.23s , +16d 05m 54.6s) |   C |     1 | 14.4 |        
Filter C is a clear (unfiltred) band. 


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