GCN Circular 44525

Subject
EP260509a: Global MASTER-Net observations report
Event
EP260509a
Date
2026-05-10T21:36:20Z (4 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) was pointed to the EP260509a ( EP Team et al., GCN 44517Loading...
 
 ) errorbox  24957 sec after notice time and 1 days 27906 sec after trigger time at 2026-05-10 21:29:08 UT, with upper limit up to  17.9 mag. The observations began at zenith distance = 61 deg. The sun  altitude  is -29.1 deg. 

The galactic latitude b = 25 deg., longitude l = 353 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3305450

We obtain a following upper limits.  

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

  114336 | 2026-05-10 21:29:08 |   MASTER-Kislovodsk | (15h 55m 47.13s , -18d 04m 15.2s) |   C |    60 | 12.6 |        
  114336 | 2026-05-10 21:29:08 |   MASTER-Kislovodsk | (15h 55m 58.90s , -18d 27m 08.8s) |   C |    60 | 17.8 |        
  114426 | 2026-05-10 21:30:38 |   MASTER-Kislovodsk | (15h 55m 42.18s , -18d 05m 11.2s) |   C |    60 | 12.1 |        
  114426 | 2026-05-10 21:30:38 |   MASTER-Kislovodsk | (15h 55m 53.95s , -18d 28m 02.6s) |   C |    60 | 17.9 |        
  114514 | 2026-05-10 21:32:06 |   MASTER-Kislovodsk | (15h 55m 55.18s , -18d 27m 07.8s) |   C |    60 | 17.9 |        
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