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/[email protected]/build/orb.v2.js"></script>

or minified file

<script src="https://cdn.jsdelivr.net/gh/lizard-isana/[email protected]/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

Copyright (c) 2012-2017 Isana Kashiwai
Licensed under the MIT license.

Administrator

Isana Kashiwai
email: isana.k at gmail.com