GCN Circular 45314

Subject
Fermi GRB 260808A: Global MASTER-Net observations report
Event
GRB 260808A
Date
2026-08-08T04:46:20Z (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),
M. Segura,  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  [1]  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260808A ( Fermi GBM team, GCN 45313Loading...
 
 ) errorbox  99 sec after notice time and 136 sec after trigger time at 2026-08-08 02:53:58 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 68 deg. The sun  altitude  is -61.1 deg. 

The galactic latitude b = -39 deg., longitude l = 84 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3463356

We obtain a following upper limits.  

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

     152 | 2026-08-08 02:53:58 |         MASTER-OAFA | (22h 48m 26.72s , +15d 27m 39.0s) |   C |    30 | 17.9 |        
     188 | 2026-08-08 02:54:35 |         MASTER-OAFA | (22h 48m 26.71s , +15d 27m 41.6s) |   C |    30 | 18.1 |        
     229 | 2026-08-08 02:55:11 |         MASTER-OAFA | (22h 48m 26.79s , +15d 27m 43.8s) |   C |    40 | 18.1 |        
     281 | 2026-08-08 02:55:58 |         MASTER-OAFA | (22h 48m 26.78s , +15d 27m 46.4s) |   C |    50 | 18.4 |        
     342 | 2026-08-08 02:56:53 |         MASTER-OAFA | (22h 48m 26.83s , +15d 27m 49.2s) |   C |    60 | 18.5 |        
     641 | 2026-08-08 03:01:23 |         MASTER-OAFA | (22h 46m 41.95s , +14d 00m 48.5s) |   C |   120 | 19.1 |        
     777 | 2026-08-08 03:03:29 |         MASTER-OAFA | (22h 46m 41.99s , +14d 00m 54.5s) |   C |   140 | 19.2 |        
     938 | 2026-08-08 03:05:55 |         MASTER-OAFA | (22h 46m 41.94s , +14d 01m 00.1s) |   C |   170 | 19.3 |        
    1060 | 2026-08-08 03:08:52 |         MASTER-OAFA | (22h 46m 41.89s , +14d 01m 04.3s) |   C |    60 | 18.8 |        
    1126 | 2026-08-08 03:09:58 |         MASTER-OAFA | (22h 46m 41.85s , +14d 01m 06.4s) |   C |    60 | 18.9 |        
    1191 | 2026-08-08 03:11:03 |         MASTER-OAFA | (22h 46m 41.82s , +14d 01m 09.3s) |   C |    60 | 18.9 |        
Filter C is a clear (unfiltred) band. 


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

[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023,  Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html