GCN Circular 43847

Subject
Fermi GRB 260226A: Global MASTER-Net observations report
Event
GRB 260226A
Date
2026-02-26T15:31:16Z (6 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-Tunka robotic telescope  [1]  located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 260226A ( Fermi GBM team, GCN 43840Loading...
 
 ) errorbox  11103 sec after notice time and 11134 sec after trigger time at 2026-02-26 13:43:30 UT, with upper limit up to  19.1 mag. The observations began at zenith distance = 59 deg. The sun  altitude  is -28.9 deg. 

The galactic latitude b = -36 deg., longitude l = 164 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3156987

We obtain a following upper limits.  

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

   11139 | 2026-02-26 13:43:30 |        MASTER-Tunka | (02h 58m 57.34s , +16d 00m 41.9s) |   C |    10 | 18.0 |        
   11139 | 2026-02-26 13:43:30 |        MASTER-Tunka | (02h 59m 23.46s , +15d 56m 15.9s) |   C |    10 | 17.9 |        
   11149 | 2026-02-26 13:43:30 |        MASTER-Tunka | (02h 59m 23.46s , +15d 56m 15.9s) |   C |    30 | 18.8 |  Coadd 
   11163 | 2026-02-26 13:43:54 |        MASTER-Tunka | (02h 58m 52.12s , +15d 59m 40.3s) |   C |    10 | 18.0 |        
   11163 | 2026-02-26 13:43:54 |        MASTER-Tunka | (02h 59m 18.19s , +15d 55m 14.9s) |   C |    10 | 17.9 |        
   11187 | 2026-02-26 13:44:17 |        MASTER-Tunka | (02h 59m 23.99s , +15d 55m 25.8s) |   C |    10 | 17.9 |        
   11187 | 2026-02-26 13:44:17 |        MASTER-Tunka | (02h 58m 57.93s , +15d 59m 51.0s) |   C |    10 | 18.1 |        
   11212 | 2026-02-26 13:44:42 |        MASTER-Tunka | (02h 58m 54.73s , +16d 01m 23.4s) |   C |    10 | 18.0 |        
   11212 | 2026-02-26 13:44:42 |        MASTER-Tunka | (02h 59m 20.78s , +15d 56m 58.6s) |   C |    10 | 17.9 |        
   11222 | 2026-02-26 13:44:42 |        MASTER-Tunka | (02h 59m 20.78s , +15d 56m 58.6s) |   C |    30 | 18.7 |  Coadd 
   11236 | 2026-02-26 13:45:07 |        MASTER-Tunka | (02h 58m 54.78s , +15d 59m 58.2s) |   C |    10 | 17.9 |        
   11236 | 2026-02-26 13:45:07 |        MASTER-Tunka | (02h 59m 20.82s , +15d 55m 33.4s) |   C |    10 | 18.0 |        
   11261 | 2026-02-26 13:45:31 |        MASTER-Tunka | (02h 58m 57.44s , +16d 01m 12.6s) |   C |    10 | 18.0 |        
   11261 | 2026-02-26 13:45:31 |        MASTER-Tunka | (02h 59m 23.48s , +15d 56m 47.9s) |   C |    10 | 17.9 |        
   11284 | 2026-02-26 13:45:55 |        MASTER-Tunka | (02h 58m 52.43s , +16d 00m 36.6s) |   C |    10 | 17.9 |        
   11284 | 2026-02-26 13:45:55 |        MASTER-Tunka | (02h 59m 18.47s , +15d 56m 12.1s) |   C |    10 | 18.0 |        
   11294 | 2026-02-26 13:45:55 |        MASTER-Tunka | (02h 59m 18.47s , +15d 56m 12.1s) |   C |    30 | 18.8 |  Coadd 
   11307 | 2026-02-26 13:46:17 |        MASTER-Tunka | (02h 58m 51.55s , +16d 01m 36.1s) |   C |    10 | 18.0 |        
   11307 | 2026-02-26 13:46:17 |        MASTER-Tunka | (02h 59m 17.60s , +15d 57m 11.6s) |   C |    10 | 17.9 |        
   11329 | 2026-02-26 13:46:40 |        MASTER-Tunka | (02h 58m 58.52s , +16d 00m 35.7s) |   C |    10 | 17.9 |        
   11329 | 2026-02-26 13:46:40 |        MASTER-Tunka | (02h 59m 24.56s , +15d 56m 11.1s) |   C |    10 | 17.9 |        
   11352 | 2026-02-26 13:47:03 |        MASTER-Tunka | (02h 59m 18.76s , +15d 55m 10.5s) |   C |    10 | 17.9 |        
   11362 | 2026-02-26 13:47:03 |        MASTER-Tunka | (02h 59m 18.77s , +15d 55m 10.4s) |   C |    30 | 18.7 |  Coadd 
   11353 | 2026-02-26 13:47:03 |        MASTER-Tunka | (02h 58m 52.73s , +15d 59m 34.6s) |   C |    10 | 18.0 |        
   11374 | 2026-02-26 13:47:25 |        MASTER-Tunka | (02h 58m 57.05s , +15d 59m 57.9s) |   C |    10 | 17.9 |        
   11374 | 2026-02-26 13:47:25 |        MASTER-Tunka | (02h 59m 23.10s , +15d 55m 33.8s) |   C |    10 | 17.9 |        
   11400 | 2026-02-26 13:47:50 |        MASTER-Tunka | (02h 58m 55.01s , +16d 01m 17.3s) |   C |    10 | 17.9 |        
   11400 | 2026-02-26 13:47:50 |        MASTER-Tunka | (02h 59m 21.06s , +15d 56m 53.3s) |   C |    10 | 17.9 |        
   11426 | 2026-02-26 13:48:13 |        MASTER-Tunka | (02h 58m 55.07s , +15d 59m 57.3s) |   C |    15 | 18.2 |        
   11426 | 2026-02-26 13:48:13 |        MASTER-Tunka | (02h 59m 21.10s , +15d 55m 33.2s) |   C |    15 | 18.2 |        
   11441 | 2026-02-26 13:48:13 |        MASTER-Tunka | (02h 59m 21.10s , +15d 55m 33.2s) |   C |    45 | 19.0 |  Coadd 
   11453 | 2026-02-26 13:48:41 |        MASTER-Tunka | (02h 58m 58.09s , +16d 01m 14.6s) |   C |    15 | 18.1 |        
   11453 | 2026-02-26 13:48:41 |        MASTER-Tunka | (02h 59m 24.14s , +15d 56m 50.8s) |   C |    15 | 18.1 |        
   11481 | 2026-02-26 13:49:08 |        MASTER-Tunka | (02h 58m 51.32s , +16d 00m 32.0s) |   C |    15 | 18.1 |        
   11481 | 2026-02-26 13:49:08 |        MASTER-Tunka | (02h 59m 17.36s , +15d 56m 08.1s) |   C |    15 | 18.1 |        
   11514 | 2026-02-26 13:49:41 |        MASTER-Tunka | (02h 58m 51.83s , +16d 01m 31.0s) |   C |    15 | 18.1 |        
   11514 | 2026-02-26 13:49:42 |        MASTER-Tunka | (02h 59m 17.88s , +15d 57m 07.4s) |   C |    15 | 18.1 |        
   11529 | 2026-02-26 13:49:42 |        MASTER-Tunka | (02h 59m 17.88s , +15d 57m 07.5s) |   C |    45 | 18.9 |  Coadd 
   11542 | 2026-02-26 13:50:09 |        MASTER-Tunka | (02h 58m 57.84s , +16d 00m 30.9s) |   C |    15 | 18.2 |        
   11542 | 2026-02-26 13:50:09 |        MASTER-Tunka | (02h 59m 23.88s , +15d 56m 07.4s) |   C |    15 | 18.1 |        
   11574 | 2026-02-26 13:50:41 |        MASTER-Tunka | (02h 58m 51.31s , +15d 59m 30.1s) |   C |    15 | 18.2 |        
   11574 | 2026-02-26 13:50:41 |        MASTER-Tunka | (02h 59m 17.33s , +15d 55m 06.6s) |   C |    15 | 18.2 |        
   11604 | 2026-02-26 13:51:11 |        MASTER-Tunka | (02h 58m 58.44s , +15d 59m 43.7s) |   C |    15 | 18.1 |        
   11604 | 2026-02-26 13:51:11 |        MASTER-Tunka | (02h 59m 24.49s , +15d 55m 20.3s) |   C |    15 | 18.1 |        
   11619 | 2026-02-26 13:51:11 |        MASTER-Tunka | (02h 59m 24.49s , +15d 55m 20.2s) |   C |    45 | 19.0 |  Coadd 
   11633 | 2026-02-26 13:51:40 |        MASTER-Tunka | (02h 58m 55.34s , +16d 01m 27.4s) |   C |    15 | 18.1 |        
   11633 | 2026-02-26 13:51:40 |        MASTER-Tunka | (02h 59m 21.38s , +15d 57m 04.2s) |   C |    15 | 18.1 |        
   11662 | 2026-02-26 13:52:09 |        MASTER-Tunka | (02h 58m 55.45s , +15d 59m 35.4s) |   C |    15 | 18.2 |        
   11662 | 2026-02-26 13:52:09 |        MASTER-Tunka | (02h 59m 21.45s , +15d 55m 12.6s) |   C |    15 | 18.1 |        
   11691 | 2026-02-26 13:52:38 |        MASTER-Tunka | (02h 58m 57.68s , +16d 00m 59.7s) |   C |    15 | 18.2 |        
   11691 | 2026-02-26 13:52:38 |        MASTER-Tunka | (02h 59m 23.70s , +15d 56m 36.7s) |   C |    15 | 18.1 |        
   11706 | 2026-02-26 13:52:38 |        MASTER-Tunka | (02h 59m 23.70s , +15d 56m 36.7s) |   C |    45 | 19.1 |  Coadd 
   11721 | 2026-02-26 13:53:08 |        MASTER-Tunka | (02h 58m 52.55s , +16d 00m 26.7s) |   C |    15 | 18.2 |        
   11721 | 2026-02-26 13:53:08 |        MASTER-Tunka | (02h 59m 18.55s , +15d 56m 04.1s) |   C |    15 | 18.1 |        
   11751 | 2026-02-26 13:53:38 |        MASTER-Tunka | (02h 58m 53.33s , +16d 01m 26.5s) |   C |    15 | 18.1 |        
   11751 | 2026-02-26 13:53:38 |        MASTER-Tunka | (02h 59m 19.32s , +15d 57m 03.9s) |   C |    15 | 18.1 |        
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