Digital zenith telescope prototype of China

Classical optical astronomy measures the direction of the local plumb line on the stellar background, and is influenced by variations of the earth gravity field. Therefore, classical optical astrometry can be used to measure and study variations of plumb line. This endows classical optical astrometric technologies special significance for the interdisciplinary researches of astronomy and geoscience, and makes them irreplaceable by technologies like very long baseline interferometry, satellite laser ranging. However, classical astrometric instruments have a major drawback of low efficiency, such as the low automaticity, more operating observers, and even operative error which makes it very difficult to reduce the random observation error in some visual instruments. To overcome this drawback, we have successfully developed the digital zenith telescope prototype (DZT-1) with the aperture of 200 mm, using charge coupled device and other advanced technologies and new equipments. As proved by test observations, DZT-1 can observe thousands of stars over one night, which significantly reduces the random observation error and increases the observation accuracy. In addition, DZT-1 has a high degree of automation, even allowing unattended observation by remote control. Besides, DZT-1 has a small-size and is easy to move, making it convenient for mobile measurement of the deflection of the vertical. In summary, DZT can be widely used in the geoscience and astronomy fields.