GCN Circular 43163

Subject
EP251220a: Global MASTER-Net observations report
Event
EP251220a
Date
2025-12-21T05:09:20Z (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 EP251220a ( EP Team et al., GCN 43162Loading...
 
 ) errorbox 23634 sec after trigger time at 2025-12-20 15:00:37 UT, with upper limit up to  17.9 mag. Observations started at twilight.  The observations began at zenith distance = 28 deg. The sun  altitude  is -14.4 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP251220a errorbox 70921 sec after trigger time at 2025-12-21 04:08:44 UT, with upper limit up to  16.1 mag. The observations began at zenith distance = 81 deg. The sun  altitude  is -35.3 deg. 

The galactic latitude b = -43 deg., longitude l = 130 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3079135

We obtain a following upper limits.  

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

   23665 | 2025-12-20 15:00:37 |   MASTER-Kislovodsk | (01h 06m 41.00s , +20d 06m 46.9s) |   C |    60 | 14.1 |        
   24358 | 2025-12-20 15:12:11 |   MASTER-Kislovodsk | (01h 13m 48.06s , +18d 34m 54.1s) |   C |    60 | 17.8 |        
   24438 | 2025-12-20 15:13:31 |   MASTER-Kislovodsk | (01h 14m 45.05s , +20d 30m 16.8s) |   C |    60 | 17.7 |        
   24598 | 2025-12-20 15:16:11 |   MASTER-Kislovodsk | (01h 01m 10.07s , +18d 35m 48.4s) |   C |    60 | 17.9 |        
   24598 | 2025-12-20 15:16:11 |   MASTER-Kislovodsk | (01h 05m 50.48s , +18d 12m 44.0s) |   C |    60 | 14.2 |        
   70952 | 2025-12-21 04:08:44 |         MASTER-OAFA | (01h 09m 37.27s , +19d 10m 42.5s) |   C |    60 | 16.1 |        
   71017 | 2025-12-21 04:09:50 |         MASTER-OAFA | (01h 09m 37.22s , +19d 10m 42.5s) |   C |    60 | 15.9 |        
   71083 | 2025-12-21 04:10:56 |         MASTER-OAFA | (01h 09m 37.31s , +19d 10m 39.9s) |   C |    60 | 15.9 |        
   71159 | 2025-12-21 04:12:11 |         MASTER-OAFA | (01h 09m 37.27s , +19d 10m 38.5s) |   C |    60 | 15.1 |        
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