SVOM/VT: Overview of data processing and GRB identifications with X-band data
Abstract
VT (the Visible Telescope) is an optical telescope onboard the SVOM (Space-based Multi-band Astronomical Variable Objects Monitor) mission, specifically designed to detect optical counterparts of gamma-ray bursts (GRBs), study their afterglows, and select high-redshift candidates. It performs rapid follow-up observations simultaneously in two channels either via autonomous platform slewing or Target of Opportunity (ToO) observations. The science images acquired by VT and transmitted via the X-band downlink system are designated as VT X-band data. This paper provides an overview of GRB optical afterglow identifications with VT and describes the ground-based processing pipeline for VT X-band data, including preprocessing, astrometric calibration, and photometry. Up to 2025 December 3, VT has followed up 111 GRBs triggered by SVOM or external missions. The overall detection rate of optical counterparts is approximately 75%. Specifically, for bursts detected by SVOM/ECLAIRs, the detection rate is 77% when observed by VT within 30 minutes after the burst. A slightly higher detection rate of 81% is achieved for GRBs triggered by external missions through rapid ToO observations with a mid-time of less than 3 hours.
Keywords
Cite
@article{arxiv.2604.24266,
title = {SVOM/VT: Overview of data processing and GRB identifications with X-band data},
author = {Hua-Li Li and Yu-Lei Qiu and Li-Ping Xin and Chao Wu and Zhu-Heng Yao and Yi-Nuo Ma and Yang Xu and Pin-Pin Zhang and Xu-Hui Han and Jing Wang and Hong-Bo Cai and Da-Wei Xu and Jesse T. Palmerio and Mao-Hai Huang and Jia-Li Zhu and Mo Zhang and Jin-Song Deng and Bertrand Cordier and Jian-Yan Wei},
journal= {arXiv preprint arXiv:2604.24266},
year = {2026}
}
Comments
Accepted for publication in the SVOM special issue in Research in Astronomy and Astrophysics; 15 pages, 11 figures