应用天文研究组知识库

光度观测是地基观测空间目标的主要手段之一,利用光度信息能够估计空间目标的相关特征信息。为了更好地了解空间目标的旋转状态,选取具有代表性的猎鹰九号火箭末级作为研究对象,由其光变信息研究旋转状态。首先利用云南天文台1.2 m光学望远镜获取猎鹰九号火箭末级的光度数据,再对目标星等进行斜距归一化,得到目标光变信息并分析目标星等随时间变化的曲线,估计大致的旋转周期,再由相位离散最小化方法计算会合周期。根据太阳、目标和测站之间的位置关系、惯性主轴指向、旋转轴指向、初始相位等因素,采用姿态旋转矩阵计算理论星等,利用最小二乘原则确定惯性主轴方向及初相角度、旋转轴指向。最后给出了猎鹰九号火箭末级的旋转周期、会合周期以及旋转轴指向等参数,为后续开展其他空间目标光度信息研究提供参考。 

Lightcurve measurement is one of the main methods for ground-based space-target observation, as the photometric information of the targets can be used to estimate their relevant characteristics. Aiming at better understanding of the rotational state of the space target,a representative upper stage of the Falcon-9 rocket is selected as the object to analyze its rotational state through light curve study. Firstly,the photometric data of the upper stage of the Falcon-9 rocket is obtained with the 1.2-m optical telescope of the Yunnan Observatories. Then the target's magnitude is processed with slant-range normalization. The photometric changing information is obtained,and the time-dependent light curve of the target magnitude is analyzed. Accordingly,the approximate rotation period of the target is estimated,and then the accurate synodic period is calculated by the phase discrete minimization method. Based on the position relationship between the Sun,the target and the observatory,the main inertial axis pointing,the rotation axis pointing,the initial phase and other factors,the theoretical magnitude is calculated using the attitude rotation matrix. The main inertial axis direction,the initial phase angle and the rotation axis pointing direction are determined as well. Finally,the parameters such as the rotational period,the synodic period and the pointing direction of the rotational axis of the upper stage of the Falcon 9 rocket are given,which can serve as a reference for following studies on the photometric information of other space targets.