Cassini光学图像的天体测量能为土星系统的历表、轨道、形成演化、行星物理等研究提供高精度的基础数据。Cassini光学系统（ISS）拍摄了44万多张图像，目前分析的不足5万张，还有大量的图像有待分析。当前天体测量技术所能测量图像的范围也还有限，精度也有大幅提高的潜力。基于我们多年ISS图像天体测量的经验，该项目拟对ISS图像做两方面的工作：（1）结合拖长星象的定心技术以及暗弱卫星的证认技术构建一套不规则土卫的高精度天体测量方法，使得不规则土卫的ISS图像可测，并对若干不规则土卫进行测量；（2）结合机器学习以及亚像素边缘检测技术实现图像中可视面边缘的准确检测，进而达成具有大可视面的规则土卫的高精度天体测量，成倍提高目前的测量精度，并测量若干规则土卫。该研究将提供创新的空间图像高精度天体测量技术，发表高精度资料，并为国内未来的空间天文观测积累技术。

The high-precision astrometry of the Cassini Images of the Saturn and its satellites can provide the important fundamental data with high precision for the study of their ephemeris, orbits, evolution, and planetary physics. The Imaging Science Subsystem (ISS) in the Cassini spacecraft has taken more than 440,000 images, a large part of them to be analyzed. At present, the existing astrometry technology is not able to process all kinds of ISS images, and there exists a great potential of improving its accuracy and precision. Based on several years of experience in studying ISS image astrometry, we intend to complete two tasks on the astrometry of ISS images in the project: (1) Developing the identification technique of the faint irregular satellites in ISS images and the centering technique of the reference star with a streaked image, we will construct a high-precision astrometry method for the ISS images of the irregular saturnian satellites, and measure several ones. (2) For the disk-resolved ISS images of the regular saturnian satellites, we will develop a method of combining machine learning and sub-pixel edge detection to accurately detect the edges of the target disk, and then achieve the high-precision astrometry of ISS image of disk-resolved object. It will greatly improve the accuracy and precision of the existing method. Moreover, The ISS images of several regular Saturnian satellites will be reduced. Finally, in the project, we will output innovative high-precision astrometry techniques for space astronomy images, publish high-precision data, and accumulate technologies for the space astronomy observations in the future in China.