GCN Circular 40964
Subject
GRB 250704A: SVOM/VT optical observation
Event
Date
2025-07-05T03:16:00Z (13 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
J. X. Cao(GXU), Y. H. Cheng(SWIFAR,YNU), L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, Z. H. Yao, Y. N. Ma, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team
SVOM/VT performed an automatic slew on the burst GRB 250704A (sb25070404) triggered by SVOM/ECLAIRs (Cao et al., GCN 40934) in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
Part of X band data was received. The optical afterglow (Schneider et al., GCN 40953) within the errorbox of Swift/XRT (Osborne et al., GCN 40950) and SVOM/MXT (Cao et al., GCN 40934) was clearly detected in both VT_B and VT_R images.
The magnitudes are VT_B=20.80+/-0.05 mag and VT_R=20.52+/-0.05 mag in AB magnitude at the mid time of 8.3 hours post the burst.
Our photometry was not corrected for Galactic extinction.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
The SVOM/VT point of contact for this burst is: Jiaxin Cao: cjx@st.gxu.edu.cn.