Determining the Astronomical Refraction and Building the Radio Wave Refractive Delay Model Measured(Ⅴ)——Acquisition of Measured Apparent Zenith Distances

The demands on accuracy of measured apparent zenith distances and the necessity of elimination of systematic errors during the time of determining the astronomical refraction and building the radio wave refractive delay corrective model are described concisely. According to the new instrumental error theory, compared with error determination techniques used in foreign high accuracy measurment instruments, measurement techniques of all kinds of major errors used in the special measurment instrument and their achievable accuracies are described. Distribution of stars in video CCD images when observed in different azimuths is also presented.