协议地固坐标系与协议惯性系的关系 协议地固坐标系与协议惯性系之间的坐 标转换需要加岁差,章动,地球自转角和极移 改正 (=(PR)(NR) Brpo( yEE: A slow gyration of Earth s axis around the pole of the ecliptic, caused mainly by the gravitational pull of the sun moon, and other planets on Earths equatorial bulg HEJ: A small periodic motion of the celestial pole of Earth with respect to the pole of the ecliptic 极移:地球自转轴相对于地球的晃动协议地固坐标系与协议惯性系的关系 协议地固坐标系与协议惯性系之间的坐 标转换需要加岁差, 章动, 地球自转角和极移 改正. (t) ( ) ( ) (t) P T T T T P 1 2 0 r = PR NR B B r 岁差：A slow gyration of Earth‘s axis around the pole of the ecliptic, caused mainly by the gravitational pull of the sun, moon, and other planets on Earth’s equatorial bulge. 章动：A small periodic motion of the celestial pole of Earth with respect to the pole of the ecliptic. 极移：地球自转轴相对于地球的晃动