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1'use strict';
2
3Object.defineProperty(exports, "__esModule", {
4 value: true
5});
6
7var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }(); /**
8 * @copyright 2013 Sonia Keys
9 * @copyright 2016 commenthol
10 * @license MIT
11 * @module nutation
12 */
13/**
14 * Nutation: Chapter 22, Nutation and the Obliquity of the Ecliptic.
15 */
16
17exports.nutation = nutation;
18exports.approxNutation = approxNutation;
19exports.meanObliquity = meanObliquity;
20exports.meanObliquityLaskar = meanObliquityLaskar;
21exports.nutationInRA = nutationInRA;
22
23var _base = require('./base');
24
25var _base2 = _interopRequireDefault(_base);
26
27var _sexagesimal = require('./sexagesimal');
28
29var _sexagesimal2 = _interopRequireDefault(_sexagesimal);
30
31function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
32
33// Nutation: Chapter 22, Nutation and the Obliquity of the Ecliptic.
34
35/**
36 * Nutation returns nutation in longitude (Δψ) and nutation in obliquity (Δε)
37 * for a given JDE.
38 *
39 * JDE = UT + ΔT, see package.
40 *
41 * Computation is by 1980 IAU theory, with terms < .0003″ neglected.
42 *
43 * Result units are radians.
44 *
45 * @param {number} jde - Julian ephemeris day
46 * @return {number[]} [Δψ, Δε] - [longitude, obliquity] in radians
47 */
48function nutation(jde) {
49 var T = _base2.default.J2000Century(jde);
50 var D = _base2.default.horner(T, 297.85036, 445267.11148, -0.0019142, 1.0 / 189474) * Math.PI / 180;
51 var M = _base2.default.horner(T, 357.52772, 35999.050340, -0.0001603, -1.0 / 300000) * Math.PI / 180;
52 var N = _base2.default.horner(T, 134.96298, 477198.867398, 0.0086972, 1.0 / 5620) * Math.PI / 180;
53 var F = _base2.default.horner(T, 93.27191, 483202.017538, -0.0036825, 1.0 / 327270) * Math.PI / 180;
54 var Ω = _base2.default.horner(T, 125.04452, -1934.136261, 0.0020708, 1.0 / 450000) * Math.PI / 180;
55 var Δψ = 0;
56 var Δε = 0;
57 // sum in reverse order to accumulate smaller terms first
58 for (var i = table22A.length - 1; i >= 0; i--) {
59 var row = table22A[i];
60 var arg = row.d * D + row.m * M + row.n * N + row.f * F + row.ω * Ω;
61
62 var _base$sincos = _base2.default.sincos(arg),
63 _base$sincos2 = _slicedToArray(_base$sincos, 2),
64 s = _base$sincos2[0],
65 c = _base$sincos2[1];
66
67 Δψ += s * (row.s0 + row.s1 * T);
68 Δε += c * (row.c0 + row.c1 * T);
69 }
70 Δψ *= 0.0001 / 3600 * (Math.PI / 180);
71 Δε *= 0.0001 / 3600 * (Math.PI / 180);
72 return [Δψ, Δε]; // (Δψ, Δε float)
73}
74/**
75 * ApproxNutation returns a fast approximation of nutation in longitude (Δψ)
76 * and nutation in obliquity (Δε) for a given JDE.
77 *
78 * Accuracy is 0.5″ in Δψ, 0.1″ in Δε.
79 *
80 * Result units are radians.
81 *
82 * @param {number} jde - Julian ephemeris day
83 * @return {number[]} [Δψ, Δε] - [longitude, obliquity] in radians
84 */
85function approxNutation(jde) {
86 var T = (jde - _base2.default.J2000) / 36525;
87 var Ω = (125.04452 - 1934.136261 * T) * Math.PI / 180;
88 var L = (280.4665 + 36000.7698 * T) * Math.PI / 180;
89 var N = (218.3165 + 481267.8813 * T) * Math.PI / 180;
90
91 var _base$sincos3 = _base2.default.sincos(Ω),
92 _base$sincos4 = _slicedToArray(_base$sincos3, 2),
93 sΩ = _base$sincos4[0],
94 cΩ = _base$sincos4[1];
95
96 var _base$sincos5 = _base2.default.sincos(2 * L),
97 _base$sincos6 = _slicedToArray(_base$sincos5, 2),
98 s2L = _base$sincos6[0],
99 c2L = _base$sincos6[1];
100
101 var _base$sincos7 = _base2.default.sincos(2 * N),
102 _base$sincos8 = _slicedToArray(_base$sincos7, 2),
103 s2N = _base$sincos8[0],
104 c2N = _base$sincos8[1];
105
106 var _base$sincos9 = _base2.default.sincos(2 * Ω),
107 _base$sincos10 = _slicedToArray(_base$sincos9, 2),
108 s2Ω = _base$sincos10[0],
109 c2Ω = _base$sincos10[1];
110
111 var Δψ = (-17.2 * sΩ - 1.32 * s2L - 0.23 * s2N + 0.21 * s2Ω) / 3600 * (Math.PI / 180);
112 var Δε = (9.2 * cΩ + 0.57 * c2L + 0.1 * c2N - 0.09 * c2Ω) / 3600 * (Math.PI / 180);
113 return [Δψ, Δε]; // (Δψ, Δε float)
114}
115
116/**
117 * MeanObliquity returns mean obliquity (ε₀) following the IAU 1980
118 * polynomial.
119 *
120 * Accuracy is 1″ over the range 1000 to 3000 years and 10″ over the range
121 * 0 to 4000 years.
122 *
123 * Result unit is radians.
124 *
125 * @param {number} jde - Julian ephemeris day
126 * @return {number} mean obliquity (ε₀)
127 */
128function meanObliquity(jde) {
129 // (22.2) p. 147
130 return _base2.default.horner(_base2.default.J2000Century(jde), new _sexagesimal2.default.Angle(false, 23, 26, 21.448).rad(), -46.815 / 3600 * (Math.PI / 180), -0.00059 / 3600 * (Math.PI / 180), 0.001813 / 3600 * (Math.PI / 180));
131}
132
133/**
134 * MeanObliquityLaskar returns mean obliquity (ε₀) following the Laskar
135 * 1986 polynomial.
136 *
137 * Accuracy over the range 1000 to 3000 years is .01″.
138 *
139 * Accuracy over the valid date range of -8000 to +12000 years is
140 * "a few seconds."
141 *
142 * Result unit is radians.
143 *
144 * @param {number} jde - Julian ephemeris day
145 * @return {number} mean obliquity (ε₀)
146 */
147function meanObliquityLaskar(jde) {
148 // (22.3) p. 147
149 return _base2.default.horner(_base2.default.J2000Century(jde) * 0.01, new _sexagesimal2.default.Angle(false, 23, 26, 21.448).rad(), -4680.93 / 3600 * (Math.PI / 180), -1.55 / 3600 * (Math.PI / 180), 1999.25 / 3600 * (Math.PI / 180), -51.38 / 3600 * (Math.PI / 180), -249.67 / 3600 * (Math.PI / 180), -39.05 / 3600 * (Math.PI / 180), 7.12 / 3600 * (Math.PI / 180), 27.87 / 3600 * (Math.PI / 180), 5.79 / 3600 * (Math.PI / 180), 2.45 / 3600 * (Math.PI / 180));
150}
151
152/**
153 * NutationInRA returns "nutation in right ascension" or "equation of the
154 * equinoxes."
155 *
156 * Result is an angle in radians.
157 *
158 * @param {number} jde - Julian ephemeris day
159 * @return {number} nutation in right ascension
160 */
161function nutationInRA(jde) {
162 var _nutation = nutation(jde),
163 _nutation2 = _slicedToArray(_nutation, 2),
164 Δψ = _nutation2[0],
165 Δε = _nutation2[1];
166
167 var ε0 = meanObliquity(jde);
168 return Δψ * Math.cos(ε0 + Δε);
169}
170
171var table22A = function () {
172 var PROPS = 'd,m,n,f,ω,s0,s1,c0,c1'.split(',');
173 var tab = [[0, 0, 0, 0, 1, -171996, -174.2, 92025, 8.9], [-2, 0, 0, 2, 2, -13187, -1.6, 5736, -3.1], [0, 0, 0, 2, 2, -2274, -0.2, 977, -0.5], [0, 0, 0, 0, 2, 2062, 0.2, -895, 0.5], [0, 1, 0, 0, 0, 1426, -3.4, 54, -0.1], [0, 0, 1, 0, 0, 712, 0.1, -7, 0], [-2, 1, 0, 2, 2, -517, 1.2, 224, -0.6], [0, 0, 0, 2, 1, -386, -0.4, 200, 0], [0, 0, 1, 2, 2, -301, 0, 129, -0.1], [-2, -1, 0, 2, 2, 217, -0.5, -95, 0.3], [-2, 0, 1, 0, 0, -158, 0, 0, 0], [-2, 0, 0, 2, 1, 129, 0.1, -70, 0], [0, 0, -1, 2, 2, 123, 0, -53, 0], [2, 0, 0, 0, 0, 63, 0, 0, 0], [0, 0, 1, 0, 1, 63, 0.1, -33, 0], [2, 0, -1, 2, 2, -59, 0, 26, 0], [0, 0, -1, 0, 1, -58, -0.1, 32, 0], [0, 0, 1, 2, 1, -51, 0, 27, 0], [-2, 0, 2, 0, 0, 48, 0, 0, 0], [0, 0, -2, 2, 1, 46, 0, -24, 0], [2, 0, 0, 2, 2, -38, 0, 16, 0], [0, 0, 2, 2, 2, -31, 0, 13, 0], [0, 0, 2, 0, 0, 29, 0, 0, 0], [-2, 0, 1, 2, 2, 29, 0, -12, 0], [0, 0, 0, 2, 0, 26, 0, 0, 0], [-2, 0, 0, 2, 0, -22, 0, 0, 0], [0, 0, -1, 2, 1, 21, 0, -10, 0], [0, 2, 0, 0, 0, 17, -0.1, 0, 0], [2, 0, -1, 0, 1, 16, 0, -8, 0], [-2, 2, 0, 2, 2, -16, 0.1, 7, 0], [0, 1, 0, 0, 1, -15, 0, 9, 0], [-2, 0, 1, 0, 1, -13, 0, 7, 0], [0, -1, 0, 0, 1, -12, 0, 6, 0], [0, 0, 2, -2, 0, 11, 0, 0, 0], [2, 0, -1, 2, 1, -10, 0, 5, 0], [2, 0, 1, 2, 2, -8, 0, 3, 0], [0, 1, 0, 2, 2, 7, 0, -3, 0], [-2, 1, 1, 0, 0, -7, 0, 0, 0], [0, -1, 0, 2, 2, -7, 0, 3, 0], [2, 0, 0, 2, 1, -7, 0, 3, 0], [2, 0, 1, 0, 0, 6, 0, 0, 0], [-2, 0, 2, 2, 2, 6, 0, -3, 0], [-2, 0, 1, 2, 1, 6, 0, -3, 0], [2, 0, -2, 0, 1, -6, 0, 3, 0], [2, 0, 0, 0, 1, -6, 0, 3, 0], [0, -1, 1, 0, 0, 5, 0, 0, 0], [-2, -1, 0, 2, 1, -5, 0, 3, 0], [-2, 0, 0, 0, 1, -5, 0, 3, 0], [0, 0, 2, 2, 1, -5, 0, 3, 0], [-2, 0, 2, 0, 1, 4, 0, 0, 0], [-2, 1, 0, 2, 1, 4, 0, 0, 0], [0, 0, 1, -2, 0, 4, 0, 0, 0], [-1, 0, 1, 0, 0, -4, 0, 0, 0], [-2, 1, 0, 0, 0, -4, 0, 0, 0], [1, 0, 0, 0, 0, -4, 0, 0, 0], [0, 0, 1, 2, 0, 3, 0, 0, 0], [0, 0, -2, 2, 2, -3, 0, 0, 0], [-1, -1, 1, 0, 0, -3, 0, 0, 0], [0, 1, 1, 0, 0, -3, 0, 0, 0], [0, -1, 1, 2, 2, -3, 0, 0, 0], [2, -1, -1, 2, 2, -3, 0, 0, 0], [0, 0, 3, 2, 2, -3, 0, 0, 0], [2, -1, 0, 2, 2, -3, 0, 0, 0]];
174
175 return tab.map(function (row) {
176 var o = {};
177 PROPS.forEach(function (p, i) {
178 o[p] = row[i];
179 });
180 return o;
181 });
182}();
183
184exports.default = {
185 nutation: nutation,
186 approxNutation: approxNutation,
187 meanObliquity: meanObliquity,
188 meanObliquityLaskar: meanObliquityLaskar,
189 nutationInRA: nutationInRA
190};
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