GCN Circular 42882
Subject
GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
Event
Date
2025-11-29T04:12:26Z (a day ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
C. Wu, H. L. Li, L.P. Xin, Y. L. Qiu (NAOC), J. T. Palmerio (CEA), W. J. Tan (IHEP), D. F. Kong (GXU) report on behalf of the SVOM team.
After the trigger by SVOM/ECLAIRs at 2025-11-29T02:32:05 UTC (T0), SVOM/VT performed an automatic slew to the burst GRB 251129A (sb25112901, Tan et al., GCN 42879). The observation began at 2025-11-29T02:43:03, 658 seconds after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
The optical counterpart reported (Angulo et al., GCN 42880) was clearly detected in the 1-bit subimages and source lists downloaded via VHF network in both channels.
The magnitudes are :
Mid_time Band Magnitude (AB)
808 sec VT_B 18.63+/-0.01 mag
808 sec VT_R 18.02+/-0.01 mag
Our photometry was derived in AB magnitude and not corrected for Galactic extinction.
Given the VT color, it is likely a low redshift GRB.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.