TITLE: GCN CIRCULAR NUMBER: 40045 SUBJECT: GRB 250403A: SVOM/VT optical observation DATE: 25/04/04 11:49:37 GMT FROM: Liping Xin at NAOC, SVOM <xlp@nao.cas.cn> L.P. Xin, Y. L. Qiu, C. Wu, H. L. Li, J . Z. H. Yao, Y. Xu, P. P. Zhang, W. J. Xie, J. Wang, X. H. Han, Y. J. Xiao, H. B. Cai, Y. N. Yi, J. Y. Wei (NAOC), Y. Julakanti, R. A. J. Eyles-Ferris (U. Leicester) report on behalf of the SVOM team: SVOM performed a Target of Opportunity observation of GRB 250403A detected by Fermi/GBM (Fermi GBM team, GCN 40025) and SVOM/ECLAIRs (Julakanti et al., GCN 40026) in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The optical afterglow (Starling et al., GCN. 40028; Wu et al., GCN 40029; Du et al., GCN 40031; Li et al., GCN 40032; Julakanti et al., GCN 40034; Ghosh et al., GCN 40039; Jiang et al., GCN 40041, Pérez-Fournon et al., GCN 40043, Brivio et al., GCN 40044) was detected with a brightness of VT_R=21.26 +/- 0.07 (AB) mag and VT_B=21.78 +/- 0.07 (AB) at the mid time of 14.26 hours after the burst. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40045. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...