introduction_to_orb.js

// Orb.js のご紹介 
// https://github.com/lizard-isana/orb.js

// Orb.js は、Webサイトなどで手軽に天体の位置計算を行うことを目的としたJavaScriptライブラリです

// 5行で惑星の位置が取れたりします

var date = new Date();
var time = new Orb.Time(date);
var SS = new Orb.SolarSystem();
var mars = new SS.Mars();
var p1 = mars.position.ecliptic(time); // x, y, z
var p2 = mars.position.equatorial(time); // ra, dec, distance

// 小惑星なんかも簡単です

var asteroid = new SS.FromKeplarian({
  "eccentricity":"0.08728849329001058",
  "inclination":"6.812676631845272",
  "longitude_of_ascending_node":"250.5660658100269",
  "argument_of_periapsis":"95.63473165761138",
  "time_of_periapsis":"2456918.756066796",
  "semi_major_axis":"1.001911878091084"
});
var p3 = asteroid.position.ecliptic(time); // x, y, z
var p4 = asteroid.position.equatorial(time); // ra, dec, distance

// 人工衛星もこんな感じで

var tle = {
  first_line:"1 25544U 98067A   15012.59173611  .00014829  00000-0  23845-3 0  7179",
  second_line:"2 25544 051.6466 140.7335 0006107 243.2909 291.5211 15.53213268923827"
}
var satellite = new Orb.Satellite(tle);
var p5 = satellite.position.geographic(time); // latitude, longitude, altitude
var p6 = satellite.position.rectangular(time); // x, y, z

// 地平座標を出すならこう

var observer = {
  "latitude":35.658,
  "longitude":139.741,
  "altitude":0
}
var obs1 = new Orb.Observation({"observer":observer,"target":mars});
var p7 = obs1.horizontal(time); // azimuth, elevation

// 人工衛星も同じです

var obs2 = new Orb.Observation({"observer":observer,"target":satellite});
var p8 = obs2.horizontal(time); // azimuth, elevation

// 赤道座標をそのまま投げても大丈夫

var obs3 = new Orb.Observation({
  "observer":observer ,
  "target":{"ra":0,"dec":0}
});
var p9 = obs3.horizontal(time); // azimuth, elevation

// な、ええやろこれ？(´･_･`)