astronomia/src/pluto.js

An astronomical library

/**
 * @copyright 2013 Sonia Keys
 * @copyright 2016 commenthol
 * @license MIT
 * @module pluto
 */
/**
 * Pluto: Chapter 37, Pluto.
 */

import base from './base.js'
import elliptic from './elliptic.js'

/**
 * Heliocentric returns J2000 heliocentric coordinates of Pluto.
 *
 * Results l, b are solar longitude and latitude in radians.
 * Result r is distance in AU.
 */
export function heliocentric (jde) {
  let l = 0
  let b = 0
  let r = 0
  const T = base.J2000Century(jde)
  const J = 34.35 + 3034.9057 * T
  const S = 50.08 + 1222.1138 * T
  const P = 238.96 + 144.96 * T
  for (const i in t37) {
    const t = t37[i]
    const [sα, cα] = base.sincos((t.i * J + t.j * S + t.k * P) * Math.PI / 180)
    l += t.lA * sα + t.lB * cα
    b += t.bA * sα + t.bB * cα
    r += t.rA * sα + t.rB * cα
  }
  l = (l + 238.958116 + 144.96 * T) * Math.PI / 180
  b = (b - 3.908239) * Math.PI / 180
  r += 40.7241346
  return { lon: l, lat: b, range: r }
}

/**
 * Astrometric returns J2000 astrometric coordinates of Pluto.
 */
export function astrometric (jde, earth) {
  const sε = base.SOblJ2000
  const cε = base.COblJ2000
  const f = function (jde) {
    const { lon, lat, range } = heliocentric(jde)
    const [sl, cl] = base.sincos(lon)
    const [sb, cb] = base.sincos(lat)
    // (37.1) p. 264
    const x = range * cl * cb
    const y = range * (sl * cb * cε - sb * sε)
    const z = range * (sl * cb * sε + sb * cε)
    return { x, y, z }
  }
  const c = elliptic.astrometricJ2000(f, jde, earth) // eslint-disable-line no-unused-vars
  return new base.Coord(c.ra, c.dec)
}

function Pt (i, j, k, lA, lB, bA, bB, rA, rB) {
  this.i = i
  this.j = j
  this.k = k
  this.lA = lA
  this.lB = lB
  this.bA = bA
  this.bB = bB
  this.rA = rA
  this.rB = rB
}

const t37 = [
  new Pt(0, 0, 1, -19.799805, 19.850055, -5.452852, -14.974862, 6.6865439, 6.8951812),
  new Pt(0, 0, 2, 0.897144, -4.954829, 3.527812, 1.67279, -1.1827535, -0.0332538),
  new Pt(0, 0, 3, 0.611149, 1.211027, -1.050748, 0.327647, 0.1593179, -0.143889),
  new Pt(0, 0, 4, -0.341243, -0.189585, 0.17869, -0.292153, -0.0018444, 0.048322),
  new Pt(0, 0, 5, 0.129287, -0.034992, 0.01865, 0.10034, -0.0065977, -0.0085431),
  new Pt(0, 0, 6, -0.038164, 0.030893, -0.030697, -0.025823, 0.0031174, -0.0006032),
  new Pt(0, 1, -1, 0.020442, -0.009987, 0.004878, 0.011248, -0.0005794, 0.0022161),
  new Pt(0, 1, 0, -0.004063, -0.005071, 0.000226, -0.000064, 0.0004601, 0.0004032),
  new Pt(0, 1, 1, -0.006016, -0.003336, 0.00203, -0.000836, -0.0001729, 0.0000234),
  new Pt(0, 1, 2, -0.003956, 0.003039, 0.000069, -0.000604, -0.0000415, 0.0000702),
  new Pt(0, 1, 3, -0.000667, 0.003572, -0.000247, -0.000567, 0.0000239, 0.0000723),
  new Pt(0, 2, -2, 0.001276, 0.000501, -0.000057, 0.000001, 0.0000067, -0.0000067),
  new Pt(0, 2, -1, 0.001152, -0.000917, -0.000122, 0.000175, 0.0001034, -0.0000451),
  new Pt(0, 2, 0, 0.00063, -0.001277, -0.000049, -0.000164, -0.0000129, 0.0000504),
  new Pt(1, -1, 0, 0.002571, -0.000459, -0.000197, 0.000199, 0.000048, -0.0000231),
  new Pt(1, -1, 1, 0.000899, -0.001449, -0.000025, 0.000217, 0.0000002, -0.0000441),
  new Pt(1, 0, -3, -0.001016, 0.001043, 0.000589, -0.000248, -0.0003359, 0.0000265),
  new Pt(1, 0, -2, -0.002343, -0.001012, -0.000269, 0.000711, 0.0007856, -0.0007832),
  new Pt(1, 0, -1, 0.007042, 0.000788, 0.000185, 0.000193, 0.0000036, 0.0045763),
  new Pt(1, 0, 0, 0.001199, -0.000338, 0.000315, 0.000807, 0.0008663, 0.0008547),
  new Pt(1, 0, 1, 0.000418, -0.000067, -0.00013, -0.000043, -0.0000809, -0.0000769),
  new Pt(1, 0, 2, 0.00012, -0.000274, 0.000005, 0.000003, 0.0000263, -0.0000144),
  new Pt(1, 0, 3, -0.00006, -0.000159, 0.000002, 0.000017, -0.0000126, 0.0000032),
  new Pt(1, 0, 4, -0.000082, -0.000029, 0.000002, 0.000005, -0.0000035, -0.0000016),
  new Pt(1, 1, -3, -0.000036, -0.000029, 0.000002, 0.000003, -0.0000019, -0.0000004),
  new Pt(1, 1, -2, -0.00004, 0.000007, 0.000003, 0.000001, -0.0000015, 0.0000008),
  new Pt(1, 1, -1, -0.000014, 0.000022, 0.000002, -0.000001, -0.0000004, 0.0000012),
  new Pt(1, 1, 0, 0.000004, 0.000013, 0.000001, -0.000001, 0.0000005, 0.0000006),
  new Pt(1, 1, 1, 0.000005, 0.000002, 0, -0.000001, 0.0000003, 0.0000001),
  new Pt(1, 1, 3, -0.000001, 0, 0, 0, 0.0000006, -0.0000002),
  new Pt(2, 0, -6, 0.000002, 0, 0, -0.000002, 0.0000002, 0.0000002),
  new Pt(2, 0, -5, -0.000004, 0.000005, 0.000002, 0.000002, -0.0000002, -0.0000002),
  new Pt(2, 0, -4, 0.000004, -0.000007, -0.000007, 0, 0.0000014, 0.0000013),
  new Pt(2, 0, -3, 0.000014, 0.000024, 0.00001, -0.000008, -0.0000063, 0.0000013),
  new Pt(2, 0, -2, -0.000049, -0.000034, -0.000003, 0.00002, 0.0000136, -0.0000236),
  new Pt(2, 0, -1, 0.000163, -0.000048, 0.000006, 0.000005, 0.0000273, 0.0001065),
  new Pt(2, 0, 0, 0.000009, -0.000024, 0.000014, 0.000017, 0.0000251, 0.0000149),
  new Pt(2, 0, 1, -0.000004, 0.000001, -0.000002, 0, -0.0000025, -0.0000009),
  new Pt(2, 0, 2, -0.000003, 0.000001, 0, 0, 0.0000009, -0.0000002),
  new Pt(2, 0, 3, 0.000001, 0.000003, 0, 0, -0.0000008, 0.0000007),
  new Pt(3, 0, -2, -0.000003, -0.000001, 0, 0.000001, 0.0000002, -0.000001),
  new Pt(3, 0, -1, 0.000005, -0.000003, 0, 0, 0.0000019, 0.0000035),
  new Pt(3, 0, 0, 0, 0, 0.000001, 0, 0.000001, 0.0000003)
]

export default {
  heliocentric,
  astrometric
}