引力偏折和延迟对VLBI时延的影响

THE INFLUENCES OF GRAVITATIONAL DEFLECTION AND RETARDATION ON VLBI TIME-DELAY

本文分析了在VLBI程序中两种不同的计算引力场对时延影响的方法,最后指出,应该直接利用两站引力延迟之差计算有关的相对论时延.目前国内VLBI处理软件中从引力偏折概念出发得到相对论时延的方法应进行改正.

In present VLBI softwares, there are two kinds of method for the consideration of the influence of gravitational field. One comes from the concept of gravitational deflection, and derives corresponding relativistic time-delay, e.g., the GSFC's CALC program, also included is the present VLBI program used in China. Another gives out the relativistic time-delay directly from the difference of gravitational retardations of the two stations. From the discussion and comparison of the two methods, it is pointed out that the difference between them is the same order of magnitude as each of them in general, which has a maximun magnitude of several decimeters, and that the JPL's model for gravitatinal retardation turns to be a correct one. Some changes should be made to the relativistic correction subroutine in Chinese VLBI softwares.