ephemeris/src/astronomy/moshier/body.js

JavaScript implementation of Moshier's ephemeris calculations for sun, planets, comets, asteroids and stars.

var plan404 = require('./plan404')

/**
 * body definition
 *
 * // body
 * epoch:        epoch = epoch of orbital elements
 * inclination:  i = inclination
 * node:         W = longitude of the ascending node
 * perihelion:   w = argument of the perihelion
 * semiAxis:     a = mean distance (semimajor axis), if 0.0 then = perihelionDistance / (1 - eccentricity)
 * dailyMotion:  dm = daily motion, if 0.0 will be calculated
 * eccentricity: ecc = eccentricity
 * anomaly:      M = mean anomaly
 * equinox:      equinox = epoch of equinox and ecliptic
 * magnitude:    mag = visual magnitude at 1AU from earth and sun
 * semiDiameter: sdiam = equatorial semidiameter at 1au, arc seconds
 * perihelionDistance: perihelion distance
 * // computed values
 * longitude:    L = computed mean longitude
 * distance:     r = computed radius vector
 * perturbation  plat = perturbation in ecliptic latitude
 *
 * // star
 * ra:           ra = right ascension, radians
 * dec:          dec = declination, radians
 * parallax:     px = parallax, radians
 * raMotion:     mura = proper motion in R.A., rad/century
 * decMotion:    mudec = proper motion in Dec., rad/century
 * velocity:     v = radial velocity, km/s
 * equinox:      equinox = epoch of equinox and ecliptic
 * magnitude:    mag = visual magnitude
 *
 * // constellation
 * index:        index of constellation (1-88)
 * raLow:        lower right ascension, in units of hours times 3600
 * raHight:      upper right ascension, in units of hours times 3600
 * dec0:         lower declination, in units of degrees times 3600
 */
var body = {
  /**
   * Sun
   */
  sun: {
    weight: 100
  },

  /*
   * Planets
   */
  mercury: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 7.0048,
    node: 48.177,
    perihelion: 29.074,
    semiAxis: 0.387098,
    dailyMotion: 4.09236,
    eccentricity: 0.205628,
    anomaly: 198.7199,
    equinox: {julian: 2446800.5},
    magnitude: -0.42,
    semiDiameter: 3.36
  },
  venus: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 3.3946,
    node: 76.561,
    perihelion: 54.889,
    semiAxis: 0.723329,
    dailyMotion: 1.60214,
    eccentricity: 0.006757,
    anomaly: 9.0369,
    equinox: {julian: 2446800.5},
    /* Note the calculated apparent visual magnitude for Venus
     * is not very accurate.
     */
    magnitude: -4.40,
    semiDiameter: 8.34
  },
  earth: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 0.0,
    node: 0.0,
    perihelion: 102.884,
    semiAxis: 0.999999,
    dailyMotion: 0.985611,
    eccentricity: 0.016713,
    anomaly: 1.1791,
    equinox: {julian: 2446800.5},
    magnitude: -3.86,
    semiDiameter: 0.0,
    longitude: 0.0, // computed
    distance: 0.0, // computed
    perturbation: 0.0 // computed
  },
  moon: {},
  mars: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 1.8498,
    node: 49.457,
    perihelion: 286.343,
    semiAxis: 1.523710,
    dailyMotion: 0.524023,
    eccentricity: 0.093472,
    anomaly: 53.1893,
    equinox: {julian: 2446800.5},
    magnitude: -1.52,
    semiDiameter: 4.68
  },
  jupiter: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 1.3051,
    node: 100.358,
    perihelion: 275.129,
    semiAxis: 5.20265,
    dailyMotion: 0.0830948,
    eccentricity: 0.048100,
    anomaly: 344.5086,
    equinox: {julian: 2446800.5},
    magnitude: -9.40,
    semiDiameter: 98.44
  },
  saturn: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 2.4858,
    node: 113.555,
    perihelion: 337.969,
    semiAxis: 9.54050,
    dailyMotion: 0.0334510,
    eccentricity: 0.052786,
    anomaly: 159.6327,
    equinox: {julian: 2446800.5},
    magnitude: -8.88,
    semiDiameter: 82.73
  },
  uranus: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 0.7738,
    node: 73.994,
    perihelion: 98.746,
    semiAxis: 19.2233,
    dailyMotion: 0.0116943,
    eccentricity: 0.045682,
    anomaly: 84.8516,
    equinox: {julian: 2446800.5},
    magnitude: -7.19,
    semiDiameter: 35.02
  },
  neptune: {
    epoch: 2446800.5, // 05.01.1987
    inclination: 1.7697,
    node: 131.677,
    perihelion: 250.623,
    semiAxis: 30.1631,
    dailyMotion: 0.00594978,
    eccentricity: 0.009019,
    anomaly: 254.2568,
    equinox: {julian: 2446800.5},
    magnitude: -6.87,
    semiDiameter: 33.50
  },
  pluto: {
    epoch: 2446640.5,
    inclination: 17.1346,
    node: 110.204,
    perihelion: 114.21,
    semiAxis: 39.4633,
    dailyMotion: 0.00397570,
    eccentricity: 0.248662,
    anomaly: 355.0554,
    equinox: {julian: 2446640.5},
    magnitude: -1.0,
    semiDiameter: 2.07
  },

  /*
   * Comets and asteroids
   */
  chiron: {
    epoch: 2456000.5,
    inclination: 6.926651533484328,
    node: 209.3851130617651,
    perihelion: 339.4595737215378,
    semiAxis: 0.0, // will be calulated if 0.0
    dailyMotion: 0.0, // will be calculated
    eccentricity: 0.3792037887546262,
    anomaly: 114.8798253094007,
    equinox: {julian: 2450109.234581196786},
    magnitude: 6.5,
    semiDiameter: 0.0,
    perihelionDistance: 8.486494269138399
  },

  /*
   * Stars (implemented, not tested)
   */
  sirius: {
    epoch: 2000,
    hmsRa: {hours: 6, minutes: 45, seconds: 8.871},
    hmsDec: {hours: -16, minutes: 42, seconds: 57.99},
    raMotion: -3.847,
    decMotion: -120.53,
    velocity: -7.6,
    parallax: 0.3751,
    magnitude: -1.46,
    ra: 0.0,
    dec: 0.0,
    equinox: {julian: 0.0}
  }
}

body.init = function () {
  for (var key in this) {
    if (Object.prototype.hasOwnProperty.call(this, key) && key != 'init') {
      // fill the 'key'
      this [key].key = key
      // fill the ptable for the body
      if (Object.prototype.hasOwnProperty.call(plan404, key)) {
        this [key].ptable = plan404 [key]
      }
    }
  }
}

module.exports = body