角距

Angular distance distrubution-based search-less algorithm for star list.

基于角距分布的星表快速查找算法。

The angular distance to a point on a celestial object, measured north or south from the celestial equator.

赤纬到达某天体一点的角距，从天体赤道向北或向南测量得出

Through the research on the angular distance between stars, detection method of the star magnitude and systematic precision, providing a theoretical basis of design and test the dynamic star simulator.

通功闭于星间角距、星等检测方式及体解粗度的研讨，为动态星模拟器的设计取检建供给了实际依据。

Fortuitously, the flyby also happens at the same time that Venus is at its maximum elongation from the Sun as seen from Earth.

幸运的是，这次飞越同时发生在金星位于同太阳间最大角距的位置上。

These quantities are used to characterize the spherical geometry of subpoints.

定义了用于刻画卫星星下点球面几何特征的两个指标：平均星间角距和星下点分布面积。

The validity of simulating star map is verified by using the angle-distance of stars and projection theorem.

利用星间角距和投影原理的性质来验证星图模拟的有效性。

In partial celestial sphere celestial Star-Identification, the initial attitude is known. With a certain angular and distance tolerance, the separation angle of the observed stars and that of the catalog stars are matched, then, the star triangles are composed in real time. According to the rules of vector rotation, the inconsistent rotation star triangles are removed. After that, put the star triangles with public vertex into star polygon.

在局部天球星图识别方面，因为已知初始姿态，在一定角距容差和星对容差范围内和已知视轴附近的导航星角距表进行角距匹配，实时组成星三角，根据矢量法则剔除旋转方向不一致的星三角后，再把拥有公共顶点的星三角组合成星多边形。

Kuehl's triangle Star-Identification, some improvement had made. With a certain angular and distance tolerance, the separation angle of the observed stars and that of the catalog stars are matched, then, the star triangles are composed in real time. According to the rules of vector rotation, the inconsistent rotation star triangles are removed. After that, put the star triangles with public vertex into star polygon.

Kuehl的三角形星图识别的基础上进行了改进，即在一定角距容差和星对容差范围内和整个导航星角距表进行角距匹配，实时组成星三角，根据矢量法则剔除旋转方向不一致的星三角，把拥有公共顶点的星三角组合成星多边形。

The following conclusions are drawn. 1 The orbit parameters that have relatively greater influence on the number and latitudinal distribution of annual occultation events are orbit inclination, orbit height, Right Ascension of Ascending Node and Argument of Perigee in turn. All four parameters have little impact on the longitudinal distribution of annual occultation events. 2 The orbit inclination of Transmitting Satellite and Receiving Satellite impacts both LEO－LEO occultation events number and their latitudinal distribution most. The number of occultation events reaches the maximum as the sum of the two inclination angles nears 180 degrees. The one that far away from 90 degrees of the two inclination angles determines the latitude range of the occultation events. 3 LEO－LEO occultation events number reaches a maximum when the heights of TS and RS are the same, and it reaches the maximum when the heights of TS and RS are 600 km . 4 The RAAN of TS and RS has a great influence on the LEO－LEO occultation number, but has little influence on occultation distribution.

结果指出：1对一年掩星事件数量及其纬度分布影响大的轨道参数依次是轨道倾角、轨道高度、升交点赤经和近地点角距；而这些参数对一年掩星事件的经度分布影响都不大；2发射卫星和接收卫星倾角之间的相互关系对掩星事件数量和纬度分布影响最大，两卫星倾角接近互补时掩星事件最多，两颗LEO卫星中与90°相差较大的倾角决定了LEO－LEO掩星事件的纬度分布范围；3发射卫星和接收卫星处于同一轨道高度时，LEO－LEO掩星事件数取得极大值，发射卫星和接收卫星都采用600 km的轨道高度，一年LEO－LEO掩星事件数最多；4 发射卫星和接收卫星升交点赤经的相互关系对LEO－LEO掩星事件数量影响很大，发射卫星和接收卫星升交点赤经之差为120°或240°时掩星事件数量最多，RAAN对掩星事件纬度和经度分布影响不大；5近地点角距对掩星事件数量和分布影响都不大。

Large initial state error and non-Gaussian distribution of state may exist in the deep-space autonomous celestial navigation, so based on the classic six orbit elements, an orbit determination method for deep-space probe is proposed by using starlight angle as measurement information and the unscented particle filter algorithm.

针对深空自主天文导航中可能存在初始状态误差较大、状态分布非高斯分布等问题，基于轨道6根数描述形式，提出了利用星光角距观测信息和UPF算法确定探测器轨道的方法。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失