95 lines
2.6 KiB
JavaScript
95 lines
2.6 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, '__esModule', { value: true });
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var base = require('./base.cjs');
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/**
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* @copyright 2013 Sonia Keys
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* @copyright 2016 commenthol
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* @license MIT
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* @module elementequinox
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*/
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/**
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* Elements are the orbital elements of a solar system object which change
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* from one equinox to another.
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*
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* @param {Number} inc - inclination
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* @param {Number} node - longitude of ascending node (Ω)
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* @param {Number} peri - argument of perihelion (ω)
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*/
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class Elements {
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constructor (inc, node, peri) {
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if (typeof inc === 'object') {
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node = inc.pode;
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peri = inc.peri;
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inc = inc.inc;
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}
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this.inc = inc || 0;
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this.node = node || 0;
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this.peri = peri || 0;
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}
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}
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// (24.4) p. 161
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const S = 0.0001139788;
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const C = 0.9999999935;
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/**
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* ReduceB1950ToJ2000 reduces orbital elements of a solar system body from
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* equinox B1950 to J2000.
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*
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* @param {Elements} eFrom
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* @returns {Elements} eTo
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*/
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function reduceB1950ToJ2000 (eFrom) {
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const W = eFrom.node - 174.298782 * Math.PI / 180;
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const [si, ci] = base["default"].sincos(eFrom.inc);
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const [sW, cW] = base["default"].sincos(W);
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const A = si * sW;
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const B = C * si * cW - S * ci;
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const eTo = new Elements();
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eTo.inc = Math.asin(Math.hypot(A, B));
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eTo.node = base["default"].pmod(174.997194 * Math.PI / 180 + Math.atan2(A, B),
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2 * Math.PI);
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eTo.peri = base["default"].pmod(eFrom.peri + Math.atan2(-S * sW, C * si - S * ci * cW),
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2 * Math.PI);
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return eTo
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}
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const Lp = 4.50001688 * Math.PI / 180;
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const L = 5.19856209 * Math.PI / 180;
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const J = 0.00651966 * Math.PI / 180;
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/**
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* ReduceB1950ToJ2000 reduces orbital elements of a solar system body from
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* equinox B1950 in the FK4 system to equinox J2000 in the FK5 system.
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*
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* @param {Elements} eFrom
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* @returns {Elements} eTo
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*/
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function reduceB1950FK4ToJ2000FK5 (eFrom) {
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const W = L + eFrom.node;
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const [si, ci] = base["default"].sincos(eFrom.inc);
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const [sJ, cJ] = base["default"].sincos(J);
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const [sW, cW] = base["default"].sincos(W);
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const eTo = new Elements();
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eTo.inc = Math.acos(ci * cJ - si * sJ * cW);
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eTo.node = base["default"].pmod(Math.atan2(si * sW, ci * sJ + si * cJ * cW) - Lp,
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2 * Math.PI);
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eTo.peri = base["default"].pmod(eFrom.peri + Math.atan2(sJ * sW, si * cJ + ci * sJ * cW),
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2 * Math.PI);
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return eTo
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}
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var elementequinox = {
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Elements,
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reduceB1950ToJ2000,
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reduceB1950FK4ToJ2000FK5
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};
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exports.Elements = Elements;
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exports["default"] = elementequinox;
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exports.reduceB1950FK4ToJ2000FK5 = reduceB1950FK4ToJ2000FK5;
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exports.reduceB1950ToJ2000 = reduceB1950ToJ2000;
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