兴隆观测基地的大气色散实测研究

Experimental study of atmospheric dispersion at Xinglong observatory

大气色散会影响高分辨率成像、测光和光谱观测的质量。利用国家天文台兴隆观测基地80 cm望远镜获得了四个波长范围和五个天顶距的大气色散实测值,波段范围为360~440 nm、360~550 nm、360~640 nm和360~790 nm,天顶距分别为59.8°、57.6°、48.1°、47.8°和36.4°。讨论了实验过程中的四种主要误差来源,测量精度约为0.6″。根据观测时的天顶距、温度、湿度和气压等数据,结合大气折射模型计算了观测当时的理论大气色散值,与实测值进行了对比分析,结果基本吻合。对大气色散的影响因素和大气色散对高精度天文观测的影响进行了探讨,为大口径高精度天文观测提供了减小大气色散影响的方法。大气色散实测和理论计算结果表明:该方法可获得较高精度的大气色散值;大气色散对大口径望远镜的高精度天文观测影响较大,需要根据观测目的采用辅助设备来减小大气色散的影响。

Atmospheric dispersion affects the observation quality of high-resolution imaging, photometry and spectrometry. It obtained atmospheric dispersion of four bands including 360-440 nm, 360-550 nm, 360-640 nm and 360-790 nm, according five zenith angles including 59.8°, 57.6°, 48.1°, 47.8° and 36.4°, with an 80 cm telescope at Xinglong Observatory. Four main sources of error were discussed in detail, and the accuracy of the measurement was about 0.6＂. Based on the zenith angle, the temperature, the humidity and the atmospheric pressure during observation, the theoretical value of atmospheric dispersion was calculated. The results of the calculation and measurement are consistent well with each other. In addition, it discussed the influence factors of atmospheric dispersion and their effect on high precision astronomical observation, and offered solutions for decreasing atmospheric dispersion for large telescope. The calculation and measured results show that： the observation method can achieve adequate precise result; and the effect of atmospheric dispersion is obvious for high-accuracy astronomical observation with large telescope, and corresponding auxiliary equipment is needed to decrease or correct atmospheric dispersion for different observation.