算法小站

stk中天体坐标系的定义中心天体坐标系统每个中心天体都有相应的坐标系统。坐标系原点均位于中心天体的质心，区别在于坐标轴的定义。每个中心天体均支持固定坐标系（Fixed coordinate system，即相对于大地无位移）、ICRF坐标系、J2000坐标系和惯性坐标系（其坐标轴相对于J2000坐标系为常值旋转）地球和月球具有最多的坐标系（月球固定坐标系的定义有不同的版本），太阳具有黄...

GPS采用10bit定义域来对每个GPS时间信息中的周数进行编码，最多可以处理1024周（2^9+2^8+2^7+2^6+2^5+2^4+2^3+2^2+2^1+2^0=1023,0~2013）,这个期间称为一个Epoch（历元）。在每个Epoch结束时，接收机将周数复位为第0周，然后再次开始计数。每个Epoch共1024周=7168天=19.62年。第一个GPS Epoch起始于GPS时198...

Time ScalesA definition for the term "time scale":16th General Assembly of the International Astronomical UnionGrenoble, France (1976)Resolution No. 4 by Commissions 4 (Ephemerides) and 31 (Tim...

% (last updated 2018-12-14)% Delta-T 1620-1972% delta-T = ET - UT for the years 1620 - 1972% ET-UT, s%% Year +0.0 +1.0 +2.0 +3.0 +4.0% -----------------------------...

% Table of time scales 1972-present, and some predictions% TT = TAI+32.184s ==> UT1-UTC = TAI-UTC - (TT-UT1) + 32.184s% Starting at TAI-UTC GPS-UTC TT-UT1 UT1-UTC%% 1972-01-01 ...

%××××××××××××××××××××××××××××××××××××××××% GPS time = TAI - 19 seconds. GPS time matched UTC from 1980-01-01% to 1981-07-01. No leap seconds are inserted into GPS time, thus% GPS time...

The different time scalesTAI = International Atomic Time (Temps Atomique International = TAI) is defined as the weighted average of the time kept by about 200 atomic clocks in over 50 n...