GCN Circular 41822

Subject
Fermi GRB 250912A: Global MASTER-Net observations report
Event
GRB 250912A
Date
2025-09-13T01:30:58Z (11 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  (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) started inspect of the Fermi GRB 250912A ( Fermi GBM team, GCN 41819Loading...
 
 ) errorbox  12109 sec after notice time and 12119 sec after trigger time at 2025-09-13 00:28:22 UT, with upper limit up to  17.0 mag. The observations began at zenith distance = 30 deg. The sun  altitude  is -24.7 deg. 

The galactic latitude b = -38 deg., longitude l = 125 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2990662

We obtain a following upper limits.  

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

   12149 | 2025-09-13 00:28:22 |   MASTER-Kislovodsk | (00h 49m 11.26s , +24d 09m 10.4s) |   C |    60 | 16.9 |        
   12323 | 2025-09-13 00:31:16 |   MASTER-Kislovodsk | (00h 49m 55.02s , +26d 01m 05.3s) |   C |    60 | 16.5 |        
   12820 | 2025-09-13 00:39:33 |   MASTER-Kislovodsk | (00h 49m 13.73s , +24d 08m 45.3s) |   C |    60 | 17.0 |        
   12996 | 2025-09-13 00:42:30 |   MASTER-Kislovodsk | (00h 49m 58.92s , +26d 02m 34.8s) |   C |    60 | 17.0 |        
   13174 | 2025-09-13 00:45:28 |   MASTER-Kislovodsk | (00h 48m 26.82s , +22d 14m 39.0s) |   C |    60 | 16.5 |        
   13353 | 2025-09-13 00:48:26 |   MASTER-Kislovodsk | (01h 04m 52.12s , +22d 13m 05.7s) |   C |    60 | 13.7 |        
   13436 | 2025-09-13 00:49:49 |   MASTER-Kislovodsk | (00h 49m 14.02s , +24d 06m 49.9s) |   C |    60 | 13.8 |        
   13521 | 2025-09-13 00:51:14 |   MASTER-Kislovodsk | (01h 05m 50.94s , +24d 08m 56.8s) |   C |    60 | 17.0 |        
Filter C is a clear (unfiltred) band. 


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