GCN Circular 41949

Subject
Fermi GRB 250922B: Global MASTER-Net observations report
Event
GRB 250922B
Date
2025-09-23T00:15:31Z (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  (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 250922B ( Fermi GBM team, GCN 41944Loading...
 
 ) errorbox  5589 sec after notice time and 5627 sec after trigger time at 2025-09-22 22:47:13 UT, with upper limit up to  18.8 mag. The observations began at zenith distance = 30 deg. The sun  altitude  is -41.0 deg. 

The galactic latitude b = -22 deg., longitude l = 156 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2997538

We obtain a following upper limits.  

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

    5658 | 2025-09-22 22:47:13 |   MASTER-Kislovodsk | (02h 52m 08.73s , +16d 41m 59.3s) |   C |    60 | 18.8 |        
    5658 | 2025-09-22 22:47:13 |   MASTER-Kislovodsk | (02h 56m 55.92s , +16d 18m 34.3s) |   C |    60 | 18.7 |        
    6457 | 2025-09-22 23:00:32 |   MASTER-Kislovodsk | (02h 52m 08.19s , +16d 41m 21.3s) |   C |    60 | 18.7 |        
    6457 | 2025-09-22 23:00:32 |   MASTER-Kislovodsk | (02h 56m 45.35s , +16d 19m 01.1s) |   C |    60 | 18.8 |        
    7065 | 2025-09-22 23:10:41 |   MASTER-Kislovodsk | (02h 52m 03.78s , +16d 43m 29.5s) |   C |    60 | 18.7 |        
    7065 | 2025-09-22 23:10:41 |   MASTER-Kislovodsk | (02h 56m 46.03s , +16d 21m 14.1s) |   C |    60 | 18.7 |        
    7673 | 2025-09-22 23:20:48 |   MASTER-Kislovodsk | (02h 52m 13.12s , +16d 43m 24.9s) |   C |    60 | 18.6 |        
    7673 | 2025-09-22 23:20:48 |   MASTER-Kislovodsk | (02h 56m 52.90s , +16d 21m 12.4s) |   C |    60 | 18.5 |        
    8471 | 2025-09-22 23:34:06 |   MASTER-Kislovodsk | (02h 52m 00.64s , +16d 41m 56.3s) |   C |    60 | 18.6 |        
    8471 | 2025-09-22 23:34:06 |   MASTER-Kislovodsk | (02h 56m 50.35s , +16d 19m 34.7s) |   C |    60 | 18.4 |        
    9420 | 2025-09-22 23:49:55 |   MASTER-Kislovodsk | (02h 39m 41.84s , +18d 28m 07.8s) |   C |    60 | 18.8 |        
    9420 | 2025-09-22 23:49:55 |   MASTER-Kislovodsk | (02h 34m 54.00s , +18d 49m 39.5s) |   C |    60 | 18.7 |        
    9916 | 2025-09-22 23:58:11 |   MASTER-Kislovodsk | (02h 53m 47.82s , +18d 37m 01.6s) |   C |    60 | 18.7 |        
    9916 | 2025-09-22 23:58:11 |   MASTER-Kislovodsk | (02h 58m 39.92s , +18d 14m 12.0s) |   C |    60 | 18.6 |        
   10088 | 2025-09-23 00:01:03 |   MASTER-Kislovodsk | (02h 39m 42.06s , +18d 28m 10.1s) |   C |    60 | 18.7 |        
   10088 | 2025-09-23 00:01:03 |   MASTER-Kislovodsk | (02h 34m 54.63s , +18d 49m 36.5s) |   C |    60 | 18.7 |        
Filter C is a clear (unfiltred) band. 


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