TITLE:   GCN CIRCULAR
NUMBER:  40278
SUBJECT: EP250428b: Global MASTER-Net observations report
DATE:    25/04/29 18:09:39 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

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  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP250428b ( EP Team et al., GCN 40277) errorbox  285 sec after notice time and 1 days 41608 sec after trigger time at 2025-04-29 17:38:59 UT, with upper limit up to  17.6 mag. Observations started at twilight.  The observations began at zenith distance = 64 deg. The sun  altitude  is -15.2 deg. 

The galactic latitude b = 53 deg., longitude l = 355 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2856874

We obtain a following upper limits.  

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

  128038 | 2025-04-29 17:38:59 |   MASTER-Kislovodsk | (14h 39m 56.30s , +02d 18m 36.2s) |   C |    60 | 17.1 |        
  128993 | 2025-04-29 17:54:54 |   MASTER-Kislovodsk | (14h 39m 58.93s , +02d 19m 39.5s) |   C |    60 | 17.5 |        
  129172 | 2025-04-29 17:57:52 |   MASTER-Kislovodsk | (14h 39m 52.83s , +02d 19m 59.5s) |   C |    60 | 17.6 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.