GCN Circular 44407

Subject
IceCube Alert 260425A: Global MASTER-Net observations report
Date
2026-04-25T11:13:28Z (8 hours 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-OAGH robotic telescope  [1]  located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the IceCube Alert 260425A (trigger No 24231696,23h 08m 20.64s , +19d 12m 57.6s, R=0.51) errorbox  38282 sec after notice time and 38350 sec after trigger time at 2026-04-25 10:46:13 UT, with upper limit up to  19.6 mag. The observations began at zenith distance = 74 deg. The sun  altitude  is -23.1 deg. 

The galactic latitude b = -37 deg., longitude l = 93 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3270297

We obtain a following upper limits.  

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

    5768 | 2026-04-25 01:42:41 |             MASTER- | (23h 08m 07.50s , +19d 12m 01.6s) |   C |    60 | 14.4 |        
   38380 | 2026-04-25 10:46:13 |         MASTER-OAGH | (23h 09m 51.08s , +18d 23m 56.6s) |   C |    60 | 18.3 |        
   38440 | 2026-04-25 10:46:13 |         MASTER-OAGH | (23h 09m 51.07s , +18d 23m 56.6s) |   C |   180 | 19.2 |  Coadd 
   38380 | 2026-04-25 10:46:13 |         MASTER-OAGH | (23h 07m 55.11s , +19d 01m 13.2s) |   C |    60 | 18.9 |        
   38440 | 2026-04-25 10:46:13 |         MASTER-OAGH | (23h 07m 55.11s , +19d 01m 13.2s) |   C |   180 | 19.6 |  Coadd 
   38450 | 2026-04-25 10:47:23 |         MASTER-OAGH | (23h 07m 55.20s , +18d 59m 50.2s) |   C |    60 | 18.9 |        
   38450 | 2026-04-25 10:47:23 |         MASTER-OAGH | (23h 09m 51.12s , +18d 22m 32.7s) |   C |    60 | 18.4 |        
   38522 | 2026-04-25 10:48:35 |         MASTER-OAGH | (23h 07m 57.46s , +19d 01m 32.3s) |   C |    60 | 18.9 |        
   38522 | 2026-04-25 10:48:35 |         MASTER-OAGH | (23h 09m 53.40s , +18d 24m 14.2s) |   C |    60 | 18.4 |        
   39727 | 2026-04-25 11:08:10 |         MASTER-OAGH | (23h 07m 52.40s , +19d 00m 52.4s) |   C |   120 | 19.0 |        
   39727 | 2026-04-25 11:08:10 |         MASTER-OAGH | (23h 09m 50.43s , +18d 23m 39.0s) |   C |   120 | 18.6 |        
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