GCN Circular 43474

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-OAFA robotic telescope  [1]  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB260120.12 (trigger No 790570272,03h 14m 19.20s , -35d 09m 36.0s, R=1.41) errorbox  133 sec after notice time and 170 sec after trigger time at 2026-01-20 02:53:57 UT, with upper limit up to  20.9 mag. The observations began at zenith distance = 41 deg. The sun  altitude  is -32.2 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB260120.12 errorbox  50498 sec after notice time and 50534 sec after trigger time at 2026-01-20 16:53:22 UT, with upper limit up to  13.0 mag. The observations began at zenith distance = 78 deg. The sun  altitude  is -30.1 deg. 

The galactic latitude b = -58 deg., longitude l = 236 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3108498

We obtain a following upper limits.  

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

     185 | 2026-01-20 02:53:57 |         MASTER-OAFA | (02h 59m 50.02s , -35d 32m 29.5s) |   C |    30 | 18.5 |        
     226 | 2026-01-20 02:54:33 |         MASTER-OAFA | (02h 59m 50.06s , -35d 32m 29.0s) |   C |    40 | 20.7 |        
     277 | 2026-01-20 02:55:19 |         MASTER-OAFA | (02h 59m 50.12s , -35d 32m 29.0s) |   C |    50 | 20.8 |        
     338 | 2026-01-20 02:56:15 |         MASTER-OAFA | (02h 59m 50.21s , -35d 32m 29.0s) |   C |    60 | 20.9 |        
   50565 | 2026-01-20 16:53:22 |   MASTER-Kislovodsk | (03h 10m 05.18s , -34d 42m 45.9s) |   C |    60 | 13.0 |        
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