GCN 45190: SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare

H. L. Li, Y. N. Ma, C. Wu, Y. L. Qiu, L. P. Xin, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC) and J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.

SVOM/VT performed observations with automatic slew to the field of X-ray transient sb26071506 triggered by SVOM/ECLAIRs (Cangemi et al., GCN 45169). The observations started at 2026-07-15T16:28:06 UTC, i.e., 327 sec post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.

The high-proper motion star V* AT Mic located within the errorbox of and MXT and ECLAIRs (Cangemi et al., GCN 45169) was saturated in both channels of VT. We performed photometry using the method described in Li et al. (2026, arXiv:2604.24266). Its brightness decreased in both channels, especially in VT_B band decayed from ~10.9 mag to ~11.2 mag in about 1.4 hours. This fading confirms this ECLAIRs trigger is related to the stellar flare.

The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center 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.