GCN Circular 42425

Subject

Swift GRB 251024A: Global MASTER-Net observations report

Event

GRB 251024A

Date

2025-10-24T17:54:39Z (3 days ago)

Edited On

2025-10-24T19:39:47Z (3 days ago)

From

Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

Edited By

Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Vladimir Lipunov at Lomonosov Moscow State University <lipunov@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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB251024.74 (trigger No 1406589,20h 26m 29.26s , -68d 34m 26.4s, R=0.05) errorbox  10 sec after notice time and 73 sec after trigger time at 2025-10-24 17:48:15 UT, with upper limit up to  16.5 mag. Observations started at twilight.  The observations began at zenith distance = 38 deg. The sun  altitude  is -11.1 deg. 

The galactic latitude b = -34 deg., longitude l = 327 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3022698

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      78 |         MASTER-SAAO |  P\ |    10 | 16.2 |        
      78 |         MASTER-SAAO |   C |    10 | 16.1 |        
     112 |         MASTER-SAAO |  P\ |    20 | 16.5 |        
     112 |         MASTER-SAAO |   C |    20 | 16.3 |        
Filter C is a clear (unfiltred) band. 


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