TITLE:   GCN CIRCULAR
NUMBER:  40793
SUBJECT: Fermi  trigger No 772128434: Global MASTER-Net observations report
DATE:    25/06/20 16:16:06 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 GRB250620.67 (trigger No 772128434,09h 30m 26.40s , +54d 57m 36.0s, R=1) errorbox  96 sec after notice time and 133 sec after trigger time at 2025-06-20 16:09:23 UT, with upper limit up to  15.7 mag. Observations started at twilight.  The observations began at zenith distance = 58 deg. The sun  altitude  is -14.4 deg. 

The galactic latitude b = 45 deg., longitude l = 161 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2910184

We obtain a following upper limits.  

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

     148 | 2025-06-20 16:09:23 |        MASTER-Tunka | (09h 40m 06.83s , +56d 13m 43.0s) |  P- |    30 | 14.9 |        
     148 | 2025-06-20 16:09:23 |             MASTER- | (09h 21m 21.53s , +56d 18m 40.7s) |   C |    30 | 14.5 |        
     250 | 2025-06-20 16:10:55 |        MASTER-Tunka | (09h 40m 05.78s , +56d 08m 46.7s) |  P- |    50 | 15.7 |        
     250 | 2025-06-20 16:10:55 |             MASTER- | (09h 21m 23.28s , +56d 13m 19.9s) |   C |    50 | 15.3 |        
Filter C is a clear (unfiltred) band. 


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