\Textit{svom}/vt: Instrument Overview, Science Objectives, and First-YearPerformance

Abstract The 44-cm Visible Telescope (VT) aboard the Space-based Variable Objects Monitor (SVOM) is a dual-band (400–650 nm and 650–1000 nm) instrument designed to detect and characterize the optical counterparts of gamma-ray bursts (GRBs) and other high-energy transients. This paper presents the VT's design, scientific objectives, observation strategies, and space/ground data processing pipelines, alongside its first-year in-orbit performance. In-orbit commissioning tests confirm a sensitivity of 22.5 AB mag (300 s exposure), extendable to ~24 AB mag through stacking. This performance enables the VT to monitor over 100 GRBs in the first year with an exceptional $\sim80\%$ detection rate for SVOM/ECLAIRS-triggered bursts and promptly observed bursts from other missions (e.g., \textit{Swift, Fermi, Einstein Probe (EP)}), outperforming \textit{Swift}/UVOT’s $\sim40\%$ rate. Beyond its exceptional detection efficiency, the VT played a key role in identifying high-redshift GRBs—most notably GRB 250314A (z = 7.3). Its deep upper limits at long wavelengths (up to 1 $\mu m$) were pivotal in guiding follow-up observations with large ground-based telescopes, enabling crucial near-infrared (NIR) detections. With its rapid response, deep sensitivity, and real-time processing capabilities, the VT is a key instrument for GRB research in \textit{SVOM}-era, enabling critical studies of GRB optical afterglows, circumburst environments, relativistic jet dynamics, and the origins of optically dark bursts.