GCN Circular 44223

Subject
EP260405a: Global MASTER-Net observations report
Event
EP260405a
Date
2026-04-06T04:09:46Z (14 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-OAFA robotic telescope  [1]  located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP260405a ( EP Team et al., GCN 44222Loading...
 
 ) errorbox 21911 sec after trigger time at 2026-04-05 09:51:38 UT, with upper limit up to  17.1 mag. Observations started at twilight.  The observations began at zenith distance = 78 deg. The sun  altitude  is -12.9 deg. 

The galactic latitude b = 42 deg., longitude l = 293 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3235319

We obtain a following upper limits.  

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

   21941 | 2026-04-05 09:51:38 |         MASTER-OAFA | (12h 18m 08.46s , -19d 48m 02.5s) |   C |    60 | 16.7 |        
   22001 | 2026-04-05 09:51:38 |         MASTER-OAFA | (12h 18m 08.45s , -19d 48m 02.5s) |   C |   180 | 17.1 |  Coadd 
   22007 | 2026-04-05 09:52:43 |         MASTER-OAFA | (12h 18m 08.49s , -19d 48m 02.4s) |   C |    60 | 16.6 |        
   22072 | 2026-04-05 09:53:49 |         MASTER-OAFA | (12h 18m 08.48s , -19d 48m 02.4s) |   C |    60 | 16.5 |        
   22138 | 2026-04-05 09:54:55 |         MASTER-OAFA | (12h 18m 08.55s , -19d 48m 02.6s) |   C |    60 | 16.5 |        
   22198 | 2026-04-05 09:54:55 |         MASTER-OAFA | (12h 18m 08.55s , -19d 48m 02.7s) |   C |   180 | 16.6 |  Coadd 
   22204 | 2026-04-05 09:56:00 |         MASTER-OAFA | (12h 18m 08.56s , -19d 48m 02.5s) |   C |    60 | 16.4 |        
   22270 | 2026-04-05 09:57:06 |         MASTER-OAFA | (12h 18m 08.63s , -19d 48m 02.7s) |   C |    60 | 16.2 |        
   22337 | 2026-04-05 09:58:13 |         MASTER-OAFA | (12h 18m 08.72s , -19d 48m 03.5s) |   C |    60 | 16.0 |        
   22397 | 2026-04-05 09:58:13 |         MASTER-OAFA | (12h 18m 08.72s , -19d 48m 03.6s) |   C |   180 | 16.3 |  Coadd 
   22402 | 2026-04-05 09:59:18 |         MASTER-OAFA | (12h 18m 08.73s , -19d 48m 03.4s) |   C |    60 | 16.0 |        
   22467 | 2026-04-05 10:00:24 |         MASTER-OAFA | (12h 18m 08.80s , -19d 48m 03.7s) |   C |    60 | 15.8 |        
   22533 | 2026-04-05 10:01:30 |         MASTER-OAFA | (12h 18m 08.89s , -19d 48m 03.9s) |   C |    60 | 15.7 |        
   22599 | 2026-04-05 10:02:35 |         MASTER-OAFA | (12h 18m 08.96s , -19d 48m 04.3s) |   C |    60 | 15.5 |        
   22665 | 2026-04-05 10:03:41 |         MASTER-OAFA | (12h 18m 09.09s , -19d 48m 04.8s) |   C |    60 | 15.3 |        
   50605 | 2026-04-05 17:48:21 |             MASTER- | (12h 17m 45.04s , -19d 54m 07.3s) |   C |   180 | 16.3 |        
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