GCN 44756: Fermi GRB 260601A: Global MASTER-Net observations report

2026-06-01T11:45:38.191Z | rev 0 | event: GRB 260601A
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-OAGH robotic telescope  [1]  located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 260601A ( Fermi GBM team, GCN 44755) errorbox  301 sec after notice time and 327 sec after trigger time at 2026-06-01 11:05:39 UT, with upper limit up to  19.5 mag. Observations started at twilight.  The observations began at zenith distance = 53 deg. The sun  altitude  is -13.8 deg. 

The galactic latitude b = -18 deg., longitude l = 125 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3352995

We obtain a following upper limits.  

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

     357 | 2026-06-01 11:05:39 |         MASTER-OAGH | (00h 50m 13.85s , +45d 57m 12.7s) |   C |    60 | 19.4 |        
     430 | 2026-06-01 11:06:52 |         MASTER-OAGH | (00h 38m 00.15s , +44d 39m 27.6s) |   C |    60 | 19.1 |        
     430 | 2026-06-01 11:06:52 |         MASTER-OAGH | (00h 48m 30.18s , +44d 02m 36.0s) |   C |    60 | 19.5 |        
     576 | 2026-06-01 11:09:18 |         MASTER-OAGH | (00h 52m 04.36s , +47d 50m 39.9s) |   C |    60 | 19.0 |        
     678 | 2026-06-01 11:10:30 |         MASTER-OAGH | (00h 59m 12.69s , +44d 07m 39.1s) |  P- |   120 | 16.9 |        
     678 | 2026-06-01 11:10:30 |         MASTER-OAGH | (01h 01m 18.88s , +43d 31m 06.4s) |  P| |   120 | 17.8 |        
     798 | 2026-06-01 11:10:30 |         MASTER-OAGH | (01h 01m 18.88s , +43d 31m 06.6s) |  P| |   360 | 18.0 |  Coadd 
     807 | 2026-06-01 11:12:39 |         MASTER-OAGH | (00h 59m 19.74s , +44d 08m 01.8s) |  P- |   120 | 16.9 |        
     807 | 2026-06-01 11:12:39 |         MASTER-OAGH | (01h 01m 25.92s , +43d 31m 26.7s) |  P| |   120 | 17.8 |        
     936 | 2026-06-01 11:14:48 |         MASTER-OAGH | (00h 59m 15.81s , +44d 09m 26.1s) |  P- |   120 | 16.9 |        
     936 | 2026-06-01 11:14:48 |         MASTER-OAGH | (01h 01m 22.64s , +43d 32m 53.3s) |  P| |   120 | 17.5 |        
    1065 | 2026-06-01 11:16:57 |         MASTER-OAGH | (00h 59m 15.96s , +44d 07m 29.9s) |  P- |   120 | 16.6 |        
    1065 | 2026-06-01 11:16:57 |         MASTER-OAGH | (01h 01m 22.92s , +43d 30m 56.4s) |  P| |   120 | 17.4 |        
    1173 | 2026-06-01 11:19:15 |         MASTER-OAGH | (00h 59m 32.67s , +44d 39m 48.6s) |   C |    60 | 18.5 |        
    1173 | 2026-06-01 11:19:15 |         MASTER-OAGH | (01h 09m 59.11s , +44d 02m 59.4s) |   C |    60 | 18.3 |        
    1246 | 2026-06-01 11:20:28 |         MASTER-OAGH | (00h 57m 41.97s , +42d 45m 11.1s) |   C |    60 | 18.2 |        
    1246 | 2026-06-01 11:20:28 |         MASTER-OAGH | (01h 07m 49.03s , +42d 08m 22.9s) |   C |    60 | 18.1 |        
    1319 | 2026-06-01 11:21:41 |         MASTER-OAGH | (01h 01m 31.23s , +46d 34m 48.3s) |   C |    60 | 18.1 |        
    1319 | 2026-06-01 11:21:41 |         MASTER-OAGH | (01h 12m 18.99s , +45d 57m 59.6s) |   C |    60 | 18.0 |        
    1393 | 2026-06-01 11:22:55 |         MASTER-OAGH | (00h 55m 58.79s , +40d 51m 00.4s) |   C |    60 | 17.8 |        
    1466 | 2026-06-01 11:24:08 |         MASTER-OAGH | (00h 47m 06.39s , +42d 09m 10.0s) |   C |    60 | 18.1 |        
    1541 | 2026-06-01 11:25:23 |         MASTER-OAGH | (01h 18m 18.85s , +42d 46m 18.7s) |   C |    60 | 17.2 |        
    1686 | 2026-06-01 11:27:48 |         MASTER-OAGH | (01h 20m 55.25s , +44d 40m 22.4s) |   C |    60 | 17.2 |        
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