GCN Circular 43347

Subject
Fermi GRB 260105A: Global MASTER-Net observations report
Event
GRB 260105A
Date
2026-01-07T03:45:50Z (5 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 260105A ( Fermi GBM team, GCN 43335Loading...
 
 ) errorbox  42914 sec after notice time and 42952 sec after trigger time at 2026-01-06 10:43:04 UT, with upper limit up to  19.2 mag. Observations started at twilight.  The observations began at zenith distance = 35 deg. The sun  altitude  is -12.9 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260105A errorbox  1 days 4422 sec after notice time and 1 days 4460 sec after trigger time at 2026-01-07 00:01:32 UT, with upper limit up to  17.2 mag. The observations began at zenith distance = 48 deg. The sun  altitude  is -50.2 deg. 

The galactic latitude b =  4 deg., longitude l = 150 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3096780

We obtain a following upper limits.  

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

   42983 | 2026-01-06 10:43:04 |        MASTER-Tunka | (04h 46m 35.26s , +57d 50m 19.5s) |   C |    60 | 19.2 |        
   42983 | 2026-01-06 10:43:04 |        MASTER-Tunka | (04h 47m 41.61s , +57d 41m 18.4s) |   C |    60 | 18.7 |        
   49648 | 2026-01-06 12:34:09 |             MASTER- | (04h 54m 01.68s , +56d 22m 44.2s) |   C |    60 | 17.3 |        
   49648 | 2026-01-06 12:34:09 |             MASTER- | (04h 52m 23.46s , +56d 56m 52.2s) |   C |    60 | 17.2 |        
   50074 | 2026-01-06 12:41:15 |             MASTER- | (04h 24m 20.56s , +60d 44m 34.6s) |   C |    60 | 17.0 |        
   50074 | 2026-01-06 12:41:15 |             MASTER- | (04h 26m 06.14s , +60d 10m 24.1s) |   C |    60 | 17.5 |        
   50393 | 2026-01-06 12:46:34 |             MASTER- | (04h 53m 57.37s , +56d 22m 05.4s) |   C |    60 | 17.6 |        
   50393 | 2026-01-06 12:46:34 |             MASTER- | (04h 52m 21.16s , +56d 56m 07.4s) |   C |    60 | 17.2 |        
   50819 | 2026-01-06 12:53:40 |             MASTER- | (04h 26m 00.27s , +60d 10m 01.0s) |   C |    60 | 17.5 |        
   50819 | 2026-01-06 12:53:40 |             MASTER- | (04h 24m 16.25s , +60d 44m 10.6s) |   C |    60 | 17.0 |        
   51136 | 2026-01-06 12:58:57 |             MASTER- | (04h 53m 56.14s , +56d 21m 50.3s) |   C |    60 | 17.3 |        
   51136 | 2026-01-06 12:58:58 |             MASTER- | (04h 52m 21.74s , +56d 55m 48.1s) |   C |    60 | 16.9 |        
   51568 | 2026-01-06 13:06:09 |             MASTER- | (04h 26m 02.40s , +60d 10m 25.4s) |   C |    60 | 16.5 |        
   51568 | 2026-01-06 13:06:09 |             MASTER- | (04h 24m 20.55s , +60d 44m 28.7s) |   C |    60 | 15.9 |        
   51886 | 2026-01-06 13:11:28 |             MASTER- | (04h 53m 50.30s , +56d 22m 14.7s) |   C |    60 | 15.8 |        
   51886 | 2026-01-06 13:11:28 |             MASTER- | (04h 52m 17.69s , +56d 56m 07.6s) |   C |    60 | 15.6 |        
   52310 | 2026-01-06 13:18:31 |             MASTER- | (04h 25m 59.19s , +60d 10m 12.1s) |   C |    60 | 15.8 |        
   52310 | 2026-01-06 13:18:31 |             MASTER- | (04h 24m 19.17s , +60d 44m 11.3s) |   C |    60 | 15.4 |        
   61752 | 2026-01-06 15:55:53 |        MASTER-Tunka | (04h 32m 04.80s , +60d 25m 18.6s) |   C |    60 | 17.8 |        
   61752 | 2026-01-06 15:55:53 |        MASTER-Tunka | (04h 30m 52.16s , +60d 33m 07.6s) |   C |    60 | 17.1 |  Coadd 
   90891 | 2026-01-07 00:01:32 |   MASTER-Kislovodsk | (04h 53m 24.59s , +56d 38m 40.5s) |   C |    60 | 17.3 |        
  102412 | 2026-01-07 03:13:34 |   MASTER-Kislovodsk | (04h 39m 35.25s , +56d 05m 19.5s) |   C |    60 | 16.3 |        
  102412 | 2026-01-07 03:13:34 |   MASTER-Kislovodsk | (04h 32m 17.01s , +56d 24m 49.6s) |   C |    60 | 16.8 |        
  102515 | 2026-01-07 03:15:16 |   MASTER-Kislovodsk | (04h 31m 43.02s , +57d 59m 37.8s) |   C |    60 | 16.5 |        
  102515 | 2026-01-07 03:15:16 |   MASTER-Kislovodsk | (04h 24m 00.92s , +58d 19m 01.2s) |   C |    60 | 16.9 |        
  102662 | 2026-01-07 03:17:43 |   MASTER-Kislovodsk | (04h 23m 11.61s , +59d 52m 00.8s) |   C |    60 | 16.7 |        
  102662 | 2026-01-07 03:17:44 |   MASTER-Kislovodsk | (04h 15m 06.89s , +60d 11m 20.5s) |   C |    60 | 17.0 |        
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