TITLE: GCN CIRCULAR NUMBER: 40187 SUBJECT: GRB 250419A: SVOM/VT optical continuous observations DATE: 25/04/21 05:15:24 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> W. J. Xie, L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, Z. H. Yao, Y. Xu, Y. N. Ma, X. H. Han, P. P. Zhang, J. Wang, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA), B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR,YNU) reported on behalf of SVOM/VT team: Several ToO observations were performed by SVOM/VT for GRB 250419A (sb25041901, Wang et al., GCN 40168) in both VT_B (400nm-650nm) and VT_R (650nm-1000nm) band. The optical counterpart (Ocelotl López et al. GCN 40169, Xin et al. GCN 40170, Zheng et al. GCN 40171, Kumar et al. GCN 40172, Lipunov et al. GCN 40179, Odeh et al. GCN circ. 40180, Perley and Bochenek GCN circ. 40181, Pankov et al. GCN 40182, and Pérez-Fournon et al. GCN 40183, Kuin et al. GCN 40185, Wu et al. GCN 40186) was clearly detected in our observations. The observations show that a re-brightening phase arise during 16.0 to 24.0 hours post the trigger, followed by a short-term plateau and then a decay later. The latest magnitude of the optical counterpart detected by SVOM/VT are: MidTime (hours) | exposure time (s) | mag(AB) | mag err | band 48.133 | 28x60 | 20.388 | 0.08 | VT_R 48.103 | 26x60 | 20.924 | 0.07 | VT_B More follow-ups are encouraged. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40187. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...