Gaia时代巨行星天然卫星的CCD天体测量

The success of Gaia astrometric satellite is revolutionary to astrometry and astronomy as well. It can obtain highly accurate positions for about 1 billion stars with their brightness between 7 - 20 mag. It can also observe many solar system objects and extragalactic objects. During its observational period of the Gaia satellite, the accuracy for lots of planetary natural satellites will reach one mas level! However, the Gaia satellite is not able to observe all planetary natural satellites. That is to say, either the Galilean satellites of Jupiter or many very faint satellites of Giant planets are not to be observed. Due to the fundamental significance to the study of our solar system origin and evolution and the importance for the deep space exploration, this project focuses on precise and accurate positional determination of the two kinds of natural satellites mentioned above. Specifically, we shall depend mainly on the observations by the 1 m and 2.4 m telescopes at the Yunnan Observatory. And we also shall develope some new CCD image-processing techniques based on our advantanges of a long term astrometric observations for some classic natural satellites. In addition to the Galilean satellites of Jupiter, some faint and irregular natural satellites will be mainly observed in order to derive their precise and accurate positions. Lastly, all observations will be published after careful researches.

Gaia天体测量卫星的成功是天体测量学乃至天文学的一场新的革命。它观测数以十亿计的亮度在7-20等的恒星，也观测太阳系内部分运动目标和河外天体等。Gaia观测相当一部分天然卫星，其位置精度可达到毫角秒量级！然而，它却不能观测所有天然卫星，尤其是木星伽利略卫星和巨行星系统内大多数暗弱的不规则卫星。鉴于天然卫星高精度定位观测对太阳系起源与演化研究的基础意义和对我国深空探测的重要性，本项目将针对Gaia观测天然卫星的不足，开发新的天体测量技术，系统观测并高精度测量上述两类天然卫星的位置。具体地，将主要依托云南天文台1米、2.4米望远镜进行系统观测，发挥项目组长期开展天然卫星天体测量观测的优势，开发新的CCD图像处理技术，重点观测四颗巨行星中离主行星较远的暗弱的（约暗达22等）不规则天然卫星、以及观测两伽利略卫星临近时的大量CCD图像，最大限度地归算出它们的精准位置，发表珍贵的观测资料。

2019年1月至2022年12月，由国家基金委资助的面上项目——Gaia时代巨行星天然卫星的CCD天体测量 (编号：11873026)按照计划执行。项目从以下4个方面进行了课题的研究：1）CCD图像的视场定标技术，实施太阳系暗弱天体的高精度位置测量；2）多芯片拼接CCD图像几何扭曲求解与间距测量；3）相互逼近天体测量方法的研究；4）空间望远镜的CCD视场定标与图像处理技术，归算得到太阳系天体的高精度位置。研究成果对我国即将于2024年发射的空间站工程巡天望远镜的天体测量应用提供了有益的参考。项目研究共发表 (含正在出版)论文22篇，其中SCI论文16篇，其他刊物论文6篇。项目培养了研究生共11名，其中博士研究生2名，硕士研究生9名。相比预期的项目目标，本项目在论文发表和研究生培养方面均超额完成。期间，项目组邀请国内外专家开展学术报告4次，参加国内外学术会议交流5人次。此外，课题组也通过本项目资助也开发了实验室网站，实时更新课题组的研究成果、论文数据、学术交流信息等，得到了国内外同行的肯定。