TITLE: GCN CIRCULAR NUMBER: 39722 SUBJECT: GRB250314A: SVOM/VT lack of bright optical candidate from VHF data DATE: 25/03/14 16:16:43 GMT FROM: SVOM_group svomgroup@bao.ac.cn
J. T. Palmerio (CEA), L.P. Xin (NAOC), S. D. Vergani (Obs. Paris), Y. Wang (PMO, CAS), Rui-Zhi Li (YNAO, CAS), Y. L. Qiu, H.L. Li., C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J.Y. Wei (NAOC), Y. Canton, M. Garnichey, (Obs. Paris) report on behalf of the SVOM/VT team:
After the trigger by SVOM/ECLAIRs at 2025-03-14T12:56:42 UTC (Tb), SVOM performed an automatic slew on the burst. SVOM/VT began observing the field at 2025-03-14T13:01:28, 285 seconds after the SVOM trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
From a preliminary analysis of the 1bit subimage and source list donwloaded via VHF, no credible candidate is identified down to VT_R~20. The subimage and source list cover ~55% of the ECLAIRs uncertainty region (Wang et al. GCN 39719).
Further analysis will be performed once the full dataset is received via X-Band.
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.
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