GCN Circular 43699

Subject
Fermi GRB 260210C: Global MASTER-Net observations report
Event
GRB 260210C
Date
2026-02-11T16:45:47Z (a day 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 GRB 260210C ( Fermi GBM team, GCN 43690Loading...
 
 ) errorbox  71030 sec after notice time and 71220 sec after trigger time at 2026-02-11 15:36:42 UT, with upper limit up to  17.7 mag. Observations started at twilight.  The observations began at zenith distance = 67 deg. The sun  altitude  is -11.6 deg. 

The galactic latitude b = -30 deg., longitude l = 87 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3128802

We obtain a following upper limits.  

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

   71250 | 2026-02-11 15:36:42 |   MASTER-Kislovodsk | (22h 34m 34.78s , +22d 28m 07.7s) |   C |    60 | 15.8 |        
   71357 | 2026-02-11 15:38:29 |   MASTER-Kislovodsk | (22h 21m 37.65s , +22d 26m 29.0s) |   C |    60 | 15.9 |        
   71964 | 2026-02-11 15:48:36 |   MASTER-Kislovodsk | (22h 27m 29.52s , +24d 20m 43.1s) |   C |    60 | 16.7 |        
   72653 | 2026-02-11 16:00:05 |   MASTER-Kislovodsk | (22h 30m 03.09s , +20d 30m 18.0s) |   C |    60 | 17.4 |        
   72765 | 2026-02-11 16:01:57 |   MASTER-Kislovodsk | (22h 14m 25.78s , +24d 18m 57.0s) |   C |    60 | 17.5 |        
   72867 | 2026-02-11 16:03:39 |   MASTER-Kislovodsk | (22h 21m 40.66s , +26d 11m 29.9s) |   C |    60 | 17.7 |        
   72975 | 2026-02-11 16:05:27 |   MASTER-Kislovodsk | (22h 47m 29.43s , +22d 24m 59.2s) |   C |    60 | 17.3 |        
   73080 | 2026-02-11 16:07:12 |   MASTER-Kislovodsk | (22h 17m 16.21s , +20d 30m 58.2s) |   C |    60 | 16.7 |        
   73648 | 2026-02-11 16:16:40 |   MASTER-Kislovodsk | (22h 42m 55.62s , +20d 31m 49.9s) |   C |    60 | 17.3 |        
   74157 | 2026-02-11 16:25:09 |   MASTER-Kislovodsk | (22h 53m 48.41s , +24d 19m 15.5s) |   C |    60 | 16.9 |        
   74286 | 2026-02-11 16:27:18 |   MASTER-Kislovodsk | (22h 44m 21.71s , +28d 05m 30.3s) |   C |    60 | 16.8 |        
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