甚长基线干涉测量源坐标时间序列的一致性与精度
Consistency and precision of very long baseline interferometry source coordinate time series
- Nanjing University（南京大学）
- Chalmers University of Technology（查尔姆斯理工大学）
- TU Wien（维也纳工业大学）
- Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）
- University of Alicante（阿利坎特大学）
- University of Chinese Academy of Sciences（中国科学院大学）
- National Research and Innovation Agency（国家研究与创新署）
- Korea Astronomy and Space Science Institute（韩国天体物理与空间科学研究院）
- University of Science and Technology（科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究比较七个分析中心的VLBI源坐标时间序列，发现多数解精度约200-400微角秒，策略和配置差异影响小，解间比较可独立估计真实随机误差。
AI中文摘要：
来自甚长基线干涉测量观测的河外射电源坐标时间序列被广泛用于评估源的位置稳定性、为天球参考架选择稳定源、评估参考架轴稳定性以及研究与源相关的天体测量变率。它们的外部一致性、真实误差以及与处理策略和分析配置的关系仍有待研究。我们旨在比较不同分析中心的坐标时间序列解，并研究处理策略和配置如何导致其差异。我们收集了来自七个分析中心的八个解，在数据选择、参考架对齐和提取共同观测会话后，选择了496个共同源。解间差异通过成对位置偏移和相关性分析来表征，真实位置误差通过N角帽（NCH）方法和自举重采样来估计。大多数解的中值加权均方根（WRMS）值为数百微角秒（$\mathrm{\mu as}$），NCH导出的中值精度在赤经约为200-300 $\mathrm{\mu as}$，在赤纬约为250-400 $\mathrm{\mu as}$。具有相似策略、软件或源约束的解表现出更高的一致性，具有更相似的WRMS值、更强的相关性和更接近的精度估计。一致性不仅受全局或独立模式区别的影响，还受详细分析配置的影响。NCH导出的精度取决于赤纬，在南天较差，并随着更多观测会话而稳定。处理策略和配置引入的差异很小；解总体保持一致。解间比较独立地估计了超出形式误差的真实随机误差。
英文摘要：
Coordinate time series of extragalactic radio sources from very long baseline interferometry observations are widely used to evaluate source positional stability, select stable sources for celestial reference frames, assess reference-frame axis stability, and investigate source-related astrometric variability. Their external consistency, realistic errors, and relation to processing strategies and analysis configurations remain to be investigated. We aim to compare coordinate time series solutions from different analysis centers and investigate how processing strategies and configurations contribute to their differences. We collected eight solutions from seven analysis centers and selected 496 common sources after data selection, reference-frame alignment, and extraction of common observing sessions. Inter-solution differences were characterized with pairwise positional offsets and correlation analysis, and realistic positional errors with the N-cornered-hat (NCH) method and bootstrap resampling. Most solutions have median weighted root mean square (WRMS) values of a few hundred microarcseconds $(\mathrm{μas})$, and the median NCH-derived precision is about 200-300 $\mathrm{μas}$ in right ascension and 250-400 $\mathrm{μas}$ in declination. Solutions with similar strategies, software, or source constraints show higher consistency, with more similar WRMS values, stronger correlations, and closer precision estimates. Consistency is affected not only by the global or independent mode distinction but also by detailed analysis configuration. NCH-derived precision depends on declination, being poorer in the southern sky, and stabilizes with more observing sessions. Processing strategies and configurations introduce marginal differences; solutions remain generally consistent. Inter-solution comparisons independently estimate realistic stochastic errors beyond formal errors.
