Title: A novel approach for the direct estimation of the instantaneous Earth rotation velocity Show Chinese title

Title: 一种直接估计瞬时地球旋转速度的新方法

Abstract: Very Long Baseline Interferometry (VLBI) measures two standard observables: group delay and fringe frequency (delay rate). While group delay is widely used to estimate a broad range of geodetic and astrometric parameters, fringe frequency has, to date, been largely ignored. Here, we show that the fringe frequency is a unique tool for direct estimation of the instantaneous Earth angular rotation velocity, which is not accessible with the group delay alone. We estimate the magnitude of the Earth angular rotation velocity using a 30-year set of VLBI data and obtain daily estimates of X and Y angles linking the Instantaneous Rotation Pole (IRP) and the International Celestial Reference System (ICRS) pole. The plain least-squares method was applied to analyse the fringe frequency available from routine geodetic VLBI observations. We estimate three components of the Earth rotation vector on a daily basis with a formal error of 1 prad/s in relative units, or better, if a large international VLBI network is at work. The newly obtained values can be used to monitor the Earth rotation irregularity in parallel to the traditional length-of-day (LOD) values and to directly assess the modern precession-nutation theory. Show Chinese abstract

Abstract: 甚长基线干涉测量（VLBI）测量两个标准可观测值：群延迟和干涉条纹频率（延迟率）。 虽然群延迟被广泛用于估计各种大地测量和天体测量参数，但到目前为止，干涉条纹频率基本上被忽略了。 在这里，我们表明干涉条纹频率是直接估计瞬时地球角旋转速度的独特工具，而这种速度仅凭群延迟无法获得。 我们使用30年的VLBI数据集来估计地球角旋转速度的大小，并获得每日的X和Y角度，这些角度将瞬时旋转极（IRP）与国际天球参考系统（ICRS）极连接起来。 普通最小二乘法被用于分析来自常规大地测量VLBI观测的干涉条纹频率。 我们每天估算地球旋转矢量的三个分量，相对单位中的正式误差为1皮弧度/秒或更小，如果有一个大型国际VLBI网络在工作的话。 新获得的数值可以用来并行监测地球旋转的不规则性，同时监测传统的日长（LOD）值，并直接评估现代的岁差-章动理论。