GCN Circular 43475

Subject
Fermi trigger No 790601190: Global MASTER-Net observations report
Date
2026-01-20T17:16:02Z (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-Kislovodsk robotic telescope  [1]  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB260120.48 (trigger No 790601190,02h 33m 50.40s , +52d 51m 00.0s, R=2.66) errorbox  18094 sec after notice time and 18127 sec after trigger time at 2026-01-20 16:28:32 UT, with upper limit up to  18.0 mag. The observations began at zenith distance = 15 deg. The sun  altitude  is -25.6 deg. 

The galactic latitude b = -7 deg., longitude l = 139 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3109139

We obtain a following upper limits.  

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

   18157 | 2026-01-20 16:28:32 |   MASTER-Kislovodsk | (02h 09m 49.63s , +52d 59m 30.1s) |   C |    60 | 18.0 |        
   18566 | 2026-01-20 16:35:21 |   MASTER-Kislovodsk | (02h 24m 49.14s , +48d 54m 14.6s) |   C |    60 | 12.7 |        
   18566 | 2026-01-20 16:35:21 |   MASTER-Kislovodsk | (02h 17m 56.92s , +49d 13m 20.4s) |   C |    60 | 18.0 |        
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