orb.js（v2）- JavaScript library for astronomical calculations

Please note: There is no compatibility orb.js v1 and v2.

orb.js has methods for the ...

Position of 8 planets(VSOP87), sun and moon
Keplerian orbital elements
Position of artificial satellites(SGP4)
Apparent position of celestial objects
Time conversions
Coordinates conversions

Library files

You can find these files in build, and minified files in build/min

orb.v2.js:
all-in-one package

orb-satellite.v2.js:
Truncated version of orb.js. If you only need calculations for artificial satellites or space debris, you use this .js file

orb-planetary.v2.js:
Truncated version of orb.js. If you only need calculations for planetary objects such as planets or asteroids

CDN

<script src="https://cdn.jsdelivr.net/gh/lizard-isana/orb.js@v2.4/build/orb.v2.js"></script>

or minified file

<script src="https://cdn.jsdelivr.net/gh/lizard-isana/orb.js@v2.4/build/min/orb.v2.min.js"></script>

Usage

English: usage.en.md
日本語: usage.ja.md

Example

var date = new Date();

// Position of planets
var mars = new Orb.VSOP("Mars");
var xyz = mars.xyz(date); // ecliptic rectangular coordinates(x, y, z)
var radec = mars.radec(date); // equatorial spherical coordinates(ra, dec, distance)

// Position of the moon
var luna = new Orb.Luna();
var xyz = luna.xyz(date); // Earth centered ecliptic rectangular coordinates (x, y, z)
var radec = luna.radec(date); // equatorial spherical coordinates(ra, dec, distance)

// Apparent position of the Sun
var sun = new Orb.Sun();
var xyz = sun.xyz(date); // Earth centered equatorial rectangular coordinates (x, y, z)
var radec = sun.radec(date); // equatorial spherical coordinates(ra, dec, distance)

// Kepler orbital elements
var asteroid = new Orb.Kepler({
  "gm": 2.9591220828559093*Math.pow(10,-4), //(au^3/d^2) default value is the sun, so you can omit this line.
  "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 xyz = asteroid.xyz(date); // ecliptic rectangular coordinates(x, y, z, xdot, ydot, zdot)
var radec = asteroid.radec(date); // equatorial spherical coordinates(ra, dec, distance)

// Cartesian state vectors to Kepler orbital elements
var orbital_elements = new Orb.CartesianToKeplerian(xyz)

// Position of artificial satellites from Two Line Elements(TLE)
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.SGP4(tle);
var xyz = satellite.xyz(date); // Earth centered equatorial rectangular coordinates (x, y, z, xdot, ydot, zdot)
var latlng = satellite.latlng(date); // geographic spherical coordinates(latitude, longitude, altitude, velocity)

// Azimuth and Elevation
var your_location = {
  "latitude":35.658,
  "longitude":139.741,
  "altitude":0
}

var observe_mars = new Orb.Observation({"observer":your_location,"target":mars});
var horizontal = observe_mars.azel(date); // horizontal coordinates(azimuth, elevation)

var observe_satellite = new Orb.Observation({"observer":your_location,"target":satellite});
var horizontal = observe_satellite.azel(date); // horizontal coordinates(azimuth, elevation)

var sirius = {
  "ra":6.75257,
  "dec":-16.7131,
  "distance":543300
}

var observe_star = new Orb.Observation({
  "observer":your_location ,
  "target":sirius
});
var horizontal = observe_star.azel(date); // horizontal coordinates(azimuth, elevation)

// Time conversion
var time = new Orb.Time(date);
var gmst = time.gmst();
var julian_date = time.jd();
var time_in_day = time.time_in_day();
var day_of_year = time.doy();

// Coordinates conversion
var equatorial_rectangular = Orb.RadecToXYZ(sirius)
var ecliptic_rectangular = Orb.EquatorialToEcliptic({"date":date,"equatorial":equatorial_rectangular})
var equatorial_rectangular = Orb.EclipticToEquatorial({"date":date,"ecliptic":ecliptic_rectangular})
var equatorial_spherical = Orb.XYZtoRadec(equatorial_rectangular)

License

Administrator

Isana Kashiwai
email: isana.k at gmail.com