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arXiv 2101.08402astro-ph.IM
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解决时延模型中的VLBI关联函数模糊问题，提高了大地测量的精度

Resolving VLBI correlator ambiguity in the time delay model improves precision of geodetic measurements

Oleg Titov, Alexei Melnikov, Yulia Lopez

备注：
Published in PASA
发表信息：
Publications of the Astronomical Society of Australia , Volume 37 , 2020 , e050
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摘要：

现代甚长基线干涉测量（VLBI）相对论延迟模型，如IERS公约中所记载的，是指信号通过干涉仪基线的两个站之一（从一对站中任意选择，称为“参考站”或“站1”）的时间历元。该模型由2002年以前使用的相关程序组成。然而，自2002年以来，一个新的相关程序，产生的VLBI群延迟指的是在地心的信号通过的时间历元已被使用。对常规VLBI模型延迟进行了相应的修正。然而，这种校正并没有在同行评审的期刊上得到全面的介绍，而且在计算IVS数据库中正式公布的最终组延迟时，使用了不同的方法。这可能会导致一个不一致的地基VLBI实验之间的群延迟由关联函数和几何模型延迟从IERS公约中使用的数据分析软件得到高达6 ps。此外，信号到达“参考站”的时刻的错误计算可能会导致更大的建模误差（高达50 ps）。本文介绍了由于从洛伦兹变换阐述的两个历元之间的过渡的校正的理由，以及对信号到达时刻的计算的不确定性建模的方法。这两个变化对于即将到来的宽带技术大地测量VLBI观测尤其重要。

英文摘要：

The modern Very Long Baseline Interferometry (VLBI) relativistic delay model, as documented in the IERS Conventions refers to the time epoch when the signal passes one of two stations of an interferometer baseline (selected arbitrarily from the pair of stations and called the 'reference station', or 'station 1'). This model consists of the previous correlation procedure used before the year 2002. However, since 2002 a new correlation procedure that produces the VLBI group delays referring to the time epoch of signal passage at the geocenter has been used. A corresponding correction to the conventional VLBI model delay has to be introduced. However, this correction has not been thoroughly presented in peer reviewed journals, and different approaches are used at the correlators to calculate the final group delays officially published in the IVS database. This may cause an inconsistency up to 6 ps for ground-based VLBI experiments between the group delay obtained by the correlator and the geometrical model delay from the IERS Conventions used in data analysis software. Moreover, a miscalculation of the signal arrival moment to the 'reference station' could result a larger modelling error (up to 50 ps). The paper presents the justification of the correction due to transition between two epochs elaborated from the Lorentz transformation, and the approach to model the uncertainty of the calculation of the signal arrival moment. The both changes are particularly essential for upcoming broadband technology geodetic VLBI observations.

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