GCN Circular 41261

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  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the IceCube Alert 250804.84 (trigger No 19914656,05h 18m 00.00s , +16d 39m 00.0s, R=0.7) errorbox  2 days 50708 sec after notice time and 2 days 50755 sec after trigger time at 2025-08-07 10:22:22 UT, with upper limit up to  18.3 mag. Observations started at twilight.  The observations began at zenith distance = 58 deg. The sun  altitude  is -12.1 deg. 

The galactic latitude b = -11 deg., longitude l = 187 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2960236

We obtain a following upper limits.  

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

  223586 | 2025-08-07 10:22:22 |         MASTER-OAFA | (05h 15m 58.59s , +15d 20m 12.5s) |   C |    60 | 18.3 |        
  223646 | 2025-08-07 10:22:22 |         MASTER-OAFA | (05h 15m 58.59s , +15d 20m 12.5s) |   C |   180 | 18.1 |  Coadd 
  223662 | 2025-08-07 10:23:38 |         MASTER-OAFA | (05h 15m 57.44s , +15d 21m 13.0s) |   C |    60 | 17.5 |        
  223737 | 2025-08-07 10:24:53 |         MASTER-OAFA | (05h 16m 04.31s , +15d 20m 13.9s) |   C |    60 | 15.5 |        
  223811 | 2025-08-07 10:26:07 |         MASTER-OAFA | (05h 18m 10.03s , +16d 30m 57.3s) |   C |    60 | 15.8 |        
Filter C is a clear (unfiltred) band. 


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