一种新的测量大气折射的方法

A new method to establish actual atmospheric refraction measurement model

大气折射是直接影响地面天体测量位置的一项较大的修正项.现有的大气折射表仅采用某一地区的大气平均密度编制而成,而实际大气密度的分布情况还受到观测站的地理环境、周围建筑物分布、气象环境等要素的影响.因此对于高精度的观测,仅用统一的大气折射表作修正是不够的,提高大气折射修正值精度的根本途径是建立观测站本地的大气折射实测模型.根据多功能天文经纬仪的特点,提出一种仅用子午方向的视天顶距测定值就可得到瞬时天文纬度测定值的方法,将这种测定值分别用于建立子午方向大气折射实测模型和各给定方位的大气折射实测模型.并且在编制观测纲要时满足一定的限制条件Σtan z→0,巧妙地压缩原有大气折射表等系统误差对瞬时天文纬度测定值的影响.

Atmospheric refraction is a major correction term which directly influences the position measurement of celestial bodies.The existing atmospheric refraction table only adopts the average atmospheric density of observation area,while the actual distribution of atmospheric density is affected by the geographical environment,building and meteorological environment of observation station.Therefore,for highly-accurate observation,it is not enough to make correction by adopting unitary refraction table. The fundamental method to improve atmospheric refraction correction accuracy is to establish atmospheric refraction measurement model of observation station.Based on the characteristics of the multi-function theodolite,this paper proposes approach which can get the instantaneous astronomical latitude value only by using apparent zenith distance of the meridian direction. Meanwhile,we have separately established the actual atmospheric refraction measurement modal of meridional direction and multiple directions.The compiling of star-choosing program is also made to meet some conditions（ Σ tan z→0） so that the system errors affecting the measurement of instantaneous astronomical latitude can be reduced artfully.