天文定姿恒星视位置解算及更新算法

Star apparent position calculation and updating method of attitude determination

恒星视位置为航天器天文定姿提供矢量信息,是星敏感器工作必备数据。针对天基恒星视位置由于受航天器光行差影响,与地心视位置有角秒量级的差别这一问题,该文基于新天文参考框架建立一种实用天基恒星视位置计算模型,该模型可计算恒星的地心视位置和站心视位置。与天文年历恒星视位置对比,赤经的差值在40ms以内,赤纬的差值在120mas以内,验证了模型的准确性。利用STK仿真轨道数据解算站心视位置,通过分析两种视位置差别提出一种定姿跟踪模式下视位置更新算法,该算法一周内精度可保持在0.6″以内。实验表明:视位置计算模型准确性高、速度快,可满足定姿初始捕获时间要求,更新算法长时可靠,提高了定姿的计算效率。

Celestial apparent position is the key data for celestial attitude determination,which provide vector information for celestial attitude determination.Due to the affect of aberration,apparent position based on space shows arc-second difference with geocentric virtual position.A model was established to calculate the apparent position of star,which based on the new astronomical reference frame,geocentric virtual position,and observer-fixed apparent position could be calculated in the model.Comparing to geocentric virtual position of astronomical almanac,the precision of right ascension could be less than 40 ms and declination difference could be less than 120 mas,thoroughly demonstrated the correction of the model;an updating algorithm was built to solve the attitude tracing problem,which kept the accuracy less than 0.6″in a week.