GCN Circular 43534

Subject
Fermi GRB 260127B: Global MASTER-Net observations report
Event
GRB 260127B
Date
2026-01-27T21:30:30Z (2 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 260127B ( Fermi GBM team, GCN 43533Loading...
 
 ) errorbox  2657 sec after notice time and 2678 sec after trigger time at 2026-01-27 20:47:11 UT, with upper limit up to  19.7 mag. The observations began at zenith distance =  7 deg. The sun  altitude  is -37.8 deg. 

The galactic latitude b = 60 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=3117123

We obtain a following upper limits.  

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

    2709 | 2026-01-27 20:47:11 |        MASTER-Tunka | (12h 37m 21.08s , +57d 00m 17.6s) |   C |    60 | 19.5 |        
    2822 | 2026-01-27 20:49:04 |        MASTER-Tunka | (12h 51m 46.69s , +57d 02m 10.2s) |   C |    60 | 19.7 |        
    2897 | 2026-01-27 20:50:19 |        MASTER-Tunka | (12h 19m 40.16s , +58d 55m 09.9s) |   C |    60 | 19.7 |        
    2970 | 2026-01-27 20:51:32 |        MASTER-Tunka | (12h 34m 49.83s , +58d 54m 52.1s) |   C |    60 | 19.7 |        
    3049 | 2026-01-27 20:52:51 |        MASTER-Tunka | (12h 27m 48.95s , +55d 06m 33.8s) |   C |    60 | 19.7 |        
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