astronomy-bundle/coordinates/calculations/precessionCalc.js

Bundle for astronomical calculations such as position of moon, sun and planets, sunrise, sunset or solar eclipses. Most of the calculations are based on Jean Meeus 'Astronomical Algorithms' book and the VSOP87 theory.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.correctPrecessionForEquatorialCoordinates = exports.correctPrecessionForEclipticCoordinates = void 0;
const epoch_1 = require("../../constants/epoch");
const timeCalc_1 = require("../../time/calculations/timeCalc");
const angleCalc_1 = require("../../utils/angleCalc");
function correctPrecessionForEclipticCoordinates(coords, jd, startingEpoch = epoch_1.EPOCH_J2000) {
    const lonRad = (0, angleCalc_1.deg2rad)(coords.lon);
    const latRad = (0, angleCalc_1.deg2rad)(coords.lat);
    const T = (0, timeCalc_1.getEpochIntervalToJ2000)(startingEpoch);
    const t = (0, timeCalc_1.getEpochInterval)(jd, startingEpoch);
    const eta = ((0, angleCalc_1.sec2deg)(47.0029) - (0, angleCalc_1.sec2deg)(0.06603) * T + (0, angleCalc_1.sec2deg)(0.00006) * Math.pow(T, 2)) * t
        + ((0, angleCalc_1.sec2deg)(-0.03302) + (0, angleCalc_1.sec2deg)(0.000598) * T) * Math.pow(t, 2)
        + (0, angleCalc_1.sec2deg)(0.00006) * Math.pow(t, 3);
    const Pi = 174.876384 + (0, angleCalc_1.sec2deg)(3289.4789) * T + (0, angleCalc_1.sec2deg)(0.60622) * Math.pow(T, 2)
        - ((0, angleCalc_1.sec2deg)(869.8089) + (0, angleCalc_1.sec2deg)(0.50498) * T) * t
        + (0, angleCalc_1.sec2deg)(0.03536) * Math.pow(t, 2);
    const p = ((0, angleCalc_1.sec2deg)(5029.0966) + (0, angleCalc_1.sec2deg)(2.22226) * T - (0, angleCalc_1.sec2deg)(0.000042) * Math.pow(T, 2)) * t
        + ((0, angleCalc_1.sec2deg)(1.11113) - (0, angleCalc_1.sec2deg)(0.000042) * T) * Math.pow(t, 2)
        + (0, angleCalc_1.sec2deg)(0.000006) * Math.pow(t, 3);
    const etaRad = (0, angleCalc_1.deg2rad)(eta);
    const PiRad = (0, angleCalc_1.deg2rad)(Pi);
    const A = Math.cos(etaRad) * Math.cos(latRad) * Math.sin(PiRad - lonRad) - Math.sin(etaRad) * Math.sin(latRad);
    const B = Math.cos(latRad) * Math.cos(PiRad - lonRad);
    const C = Math.cos(etaRad) * Math.sin(latRad) + Math.sin(etaRad) * Math.cos(latRad) * Math.sin(PiRad - lonRad);
    const lon = p + Pi - (0, angleCalc_1.rad2deg)(Math.atan2(A, B));
    const lat = (0, angleCalc_1.rad2deg)(Math.asin(C));
    return {
        lon: (0, angleCalc_1.normalizeAngle)(lon),
        lat: lat,
        radiusVector: coords.radiusVector,
    };
}
exports.correctPrecessionForEclipticCoordinates = correctPrecessionForEclipticCoordinates;
function correctPrecessionForEquatorialCoordinates(coords, jd, startingEpoch = epoch_1.EPOCH_J2000) {
    const raRad = (0, angleCalc_1.deg2rad)(coords.rightAscension);
    const dRad = (0, angleCalc_1.deg2rad)(coords.declination);
    const T = (0, timeCalc_1.getEpochIntervalToJ2000)(startingEpoch);
    const t = (0, timeCalc_1.getEpochInterval)(jd, startingEpoch);
    const xi = ((0, angleCalc_1.sec2deg)(2306.2181) + (0, angleCalc_1.sec2deg)(1.39656) * T - (0, angleCalc_1.sec2deg)(0.000139) * Math.pow(T, 2)) * t
        + ((0, angleCalc_1.sec2deg)(0.30188) - (0, angleCalc_1.sec2deg)(0.000344) * T) * Math.pow(t, 2)
        + (0, angleCalc_1.sec2deg)(0.017988) * Math.pow(t, 3);
    const zeta = ((0, angleCalc_1.sec2deg)(2306.2181) + (0, angleCalc_1.sec2deg)(1.39656) * T - (0, angleCalc_1.sec2deg)(0.000139) * Math.pow(T, 2)) * t
        + ((0, angleCalc_1.sec2deg)(1.09468) + (0, angleCalc_1.sec2deg)(0.000066) * T) * Math.pow(t, 2)
        + (0, angleCalc_1.sec2deg)(0.018203) * Math.pow(t, 3);
    const theta = ((0, angleCalc_1.sec2deg)(2004.3109) - (0, angleCalc_1.sec2deg)(0.8533) * T - (0, angleCalc_1.sec2deg)(0.000217) * Math.pow(T, 2)) * t
        - ((0, angleCalc_1.sec2deg)(0.42665) + (0, angleCalc_1.sec2deg)(0.000217) * T) * Math.pow(t, 2)
        - (0, angleCalc_1.sec2deg)(0.041833) * Math.pow(t, 3);
    const xiRad = (0, angleCalc_1.deg2rad)(xi);
    const thetaRad = (0, angleCalc_1.deg2rad)(theta);
    const A = Math.cos(dRad) * Math.sin(raRad + xiRad);
    const B = Math.cos(thetaRad) * Math.cos(dRad) * Math.cos(raRad + xiRad) - Math.sin(thetaRad) * Math.sin(dRad);
    const C = Math.sin(thetaRad) * Math.cos(dRad) * Math.cos(raRad + xiRad) + Math.cos(thetaRad) * Math.sin(dRad);
    const rightAscension = (0, angleCalc_1.rad2deg)(Math.atan2(A, B)) + zeta;
    const declination = (0, angleCalc_1.rad2deg)(Math.asin(C));
    return {
        rightAscension: (0, angleCalc_1.normalizeAngle)(rightAscension),
        declination: declination,
        radiusVector: coords.radiusVector,
    };
}
exports.correctPrecessionForEquatorialCoordinates = correctPrecessionForEquatorialCoordinates;