摘要
本文对VLBI相对论时延作了重新推导,在保证1.0*10^(-12)秒的精度要求下,给出了在太阳系质心坐标系中的坐标时时延与在地球局部坐标系中的原时时延之间的转换关系;提出了在目前所采用的时延转换计算软件中应引入太阳引力势修正项;在最新的CALC 7.0时延计算公式中应加入有关的毫米和亚毫米的修正项.将本文推导的结果与其他作者的结果进行了比较,从而澄清了过去结果中某些改正项的正负号差异.
The VLBI relativistic geometric time delay model of transformation from the barycentric frame of the Solar System to the local frame is derived with the requirement of millimeter precision. The result differs from some other models in an additional term (2Φ@)/(c^2)·δt_0 caused by the gravitational potential of the Sun. It also differs from the models of Shapiro et al. (1989) and Hellings (1986), that have been applied to the CALC 7.0, in the additional terms ·δt_0 and ·δt_0 caused by the geocentric velocity R. The maximum order of magnitude of these two additional terms can reach 6.6* 10^(-12)s and 3.3*10^(-12)s respectively. Our result also includes producted term △t_v·, which was ignored in the previous results, and its maximum order of magnitude can reach a few millimeters. The quantity △t_v involves the gravitational retardation term △t_(grav,⊙) caused by the sun, the tropospheric and ionospheric refraction delays, and the axis offset refraction delay. In this paper, a comparison with the recent results obtained by Zhu, et al,(1988) and Sorrel, et al. (1990) is also made. According to their definition of b, the physical baseline vector between two antennas, the term — should not have a negative sign. On the contrary, the ·δt_0 term should have a negative sign. It becomes the term —·δt_0, so as to keep consistency with the results derived by others. As a conclusion, all the possible terms that are larger than 1 ps should be taken into account in the relativistic VLBI theory model. For an accuracy of 1 ps our result differs from all those that have been published earlier.
出处
《天文学报》
CSCD
北大核心
1992年第2期201-211,共11页
Acta Astronomica Sinica
基金
国家八五重点项目资助课题
关键词
太阳
时延转换
引力时延
VLBI
gravitational delay—accuracy of millimeter order—transformation of VLBI delay
