GCN Circular 43803

Subject
EP260221a: Global MASTER-Net observations report
Event
EP260221a
Date
2026-02-22T08:54:25Z (2 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 EP260221a ( EP Team et al., GCN 43791Loading...
 
 ) errorbox  44530 sec after notice time and 51263 sec after trigger time at 2026-02-22 01:57:37 UT, with upper limit up to  13.5 mag. The observations began at zenith distance = 76 deg. The sun  altitude  is -22.8 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP260221a errorbox  53402 sec after notice time and 60136 sec after trigger time at 2026-02-22 04:25:30 UT, with upper limit up to  20.7 mag. The observations began at zenith distance = 27 deg. The sun  altitude  is -48.3 deg. 

The galactic latitude b = 40 deg., longitude l = 286 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3149283

We obtain a following upper limits.  

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

   51354 | 2026-02-22 01:57:37 |   MASTER-Kislovodsk | (11h 54m 51.01s , -20d 28m 04.3s) |   C |   180 | 13.5 |        
   60167 | 2026-02-22 04:25:30 |         MASTER-OAFA | (11h 50m 53.67s , -20d 40m 02.3s) |   C |    60 | 20.3 |        
   60227 | 2026-02-22 04:25:30 |         MASTER-OAFA | (11h 50m 53.67s , -20d 40m 02.4s) |   C |   180 | 20.5 |  Coadd 
   60243 | 2026-02-22 04:26:46 |         MASTER-OAFA | (11h 50m 48.37s , -20d 40m 39.3s) |   C |    60 | 20.3 |        
   60317 | 2026-02-22 04:28:00 |         MASTER-OAFA | (11h 50m 49.21s , -20d 39m 36.9s) |   C |    60 | 18.6 |        
   60395 | 2026-02-22 04:29:18 |         MASTER-OAFA | (11h 59m 28.08s , -20d 41m 19.6s) |   C |    60 | 19.8 |        
   60455 | 2026-02-22 04:29:18 |         MASTER-OAFA | (11h 59m 28.07s , -20d 41m 19.6s) |   C |   180 | 20.7 |  Coadd 
   60474 | 2026-02-22 04:30:37 |         MASTER-OAFA | (11h 59m 24.96s , -20d 40m 07.1s) |   C |    60 | 20.2 |        
   60551 | 2026-02-22 04:31:54 |         MASTER-OAFA | (11h 59m 25.03s , -20d 41m 43.3s) |   C |    60 | 20.2 |        
   75471 | 2026-02-22 08:39:34 |             MASTER- | (11h 56m 08.31s , -21d 31m 03.3s) |   C |   180 | 19.7 |        
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