AI 中文总结
该研究针对LAMOST MRS的RV零点系统误差，提出两级校准方法并发布增值星表，使RV精度提升约2倍，支持跨多维度的一致视向速度分析。
AI 中文摘要
LAMOST中分辨率光谱巡天（MRS）为银河系运动学和时域视向速度（RV）研究提供了大型恒星光谱数据集。然而，其多光谱仪、多曝光、多光纤的观测策略会引入跨仪器和时间层级变化的RV零点（RVZP）系统误差。我们使用Gaia DR3经色指数改正的RV和APOGEE DR17 RV作为外部参考，构建了针对LAMOST DR12 MRS的两级经验RVZP改正：第一级是基于（lmjm, planid, spid）单位的光谱仪-曝光改正，第二级是基于（spid, fiberid, time_tag）单位的光纤-时间改正。在每个单位内，通过加权中位数估计器从Gaia和APOGEE的残差中估算RVZP，并将其从管道RV中减去以得到改正后的速度。对于高信噪比（S/N）光谱，经过完整的两级改正后，相对于APOGEE DR17的弥散从约1.1 km/s降至约0.52 km/s，意味着RV精度提升约2倍。我们发布了包含11,129,477条蓝臂光谱的两级改正RV增值星表，其中包括8,158,271条单曝光光谱和2,971,206条叠加光谱，可实现跨曝光、光谱仪、光纤和时间的一致RV分析。
英文摘要
The LAMOST Medium-Resolution Survey (MRS) provides a large stellar spectroscopic data set for Galactic kinematics and time-domain radial-velocity (RV) studies. However, the multi-spectrograph, multi-exposure, multi-fiber observing strategy can imprint RV zero-point (RVZP) systematics that vary across instrumental and temporal hierarchies. We construct a two-level empirical RVZP correction to LAMOST DR12 MRS using Gaia DR3 magnitude-colour-corrected RVs and APOGEE DR17 RVs as external references: a spectrograph-exposure correction in (lmjm, planid, spid) units, followed by a fiber-time correction in (spid, fiberid, time_tag) units. Within each unit, RVZPs are estimated from Gaia and APOGEE residuals using a weighted-median estimator, and are subtracted from the pipeline RVs to obtain corrected velocities. For high-S/N spectra, the scatter relative to APOGEE DR17 decreases from ~1.1 km/s to ~0.52 km/s after the full two-level correction, implying a ~2x improvement in RV precision. We release a value-added catalogue of two-level-corrected RVs for 11,129,477 blue-arm spectra, including 8,158,271 single-exposure spectra and 2,971,206 coadded spectra, enabling consistent RV analyses across exposures, spectrographs, fibers, and time.
Comments18 pages, 12 figures. Catalogue available at https://doi.org/10.5281/zenodo.21467895 ; pipeline at https://github.com/CrotRest/lamost-mrs-rvzp. Accepted by ApJS
