GCN Circular 45905

Subject

Swift GRB 261011A: Global MASTER-Net observations report

Event

GRB 261011A

Date

2026-10-11T17:46:58Z (17 hours ago)

From

Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

Via

D.Buckley (SAAO),

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 (Lomonosov MSU)

A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
A.Sosnovskij (Lomonosov MSU)

A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory)

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)

R.Rebolo (The Instituto de Astrofisica de Canarias)

O.Gress, N.Budnev(ISU)

M. Segura,  F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA)


MASTER-SAAO robotic telescope  [1]  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 261011A ( S. B. Cenko et al., GCN 45896Loading...
 
 ) errorbox  13536 sec after notice time and 13752 sec after trigger time at 2026-10-11 17:35:53 UT, with upper limit up to  18.0 mag. Observations started at twilight.  The observations began at zenith distance = 67 deg. The sun  altitude  is -11.5 deg. 

The galactic latitude b = -79 deg., longitude l = 181 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3524824

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   13842 |         MASTER-SAAO |   C |   180 | 18.0 |        
   13842 |         MASTER-SAAO |   C |   180 | 17.8 |        
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