ootk
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Orbital Object Toolkit including Multiple Propagators, Initial Orbit Determination, and Maneuver Calculations.
109 lines • 4.07 kB
JavaScript
/**
* @author @thkruz Theodore Kruczek
* @description Orbital Object ToolKit (ootk) is a collection of tools for working
* with satellites and other orbital objects.
* @license AGPL-3.0-or-later
* @copyright (c) 2025 Kruczek Labs LLC
*
* Many of the classes are based off of the work of @david-rc-dayton and his
* Pious Squid library (https://github.com/david-rc-dayton/pious_squid) which
* is licensed under the MIT license.
*
* Orbital Object ToolKit is free software: you can redistribute it and/or modify it under the
* terms of the GNU Affero General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* Orbital Object ToolKit is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License along with
* Orbital Object ToolKit. If not, see <http://www.gnu.org/licenses/>.
*/
import { secondsPerDay } from '../utils/constants.js';
// / Base class for [Epoch] data.
export class Epoch {
posix;
/*
* Create a new [Epoch] object given the number of seconds elapsed since the
* [posix] epoch _(`1970-01-01T00:00:00.000`)_ in the [Epoch] time scale.
*/
constructor(posix) {
this.posix = posix;
if (posix < 0) {
throw new Error('Epoch cannot be negative');
}
}
toString() {
return this.toDateTime().toISOString();
}
// / Convert this to an Excel spreadsheet string.
toExcelString() {
return this.toString().substring(0, 19);
}
// / Return the difference _(s)_ between this and another [epoch]/
difference(epoch) {
return this.posix - epoch.posix;
}
// / Check if this has the same timestamp as the provided [epoch].
equals(epoch) {
return this.posix === epoch.posix;
}
// / Convert to a [DateTime] object.
toDateTime() {
return new Date(this.posix * 1000);
}
toEpochYearAndDay() {
const currentDateObj = this.toDateTime();
const epochYear = currentDateObj.getUTCFullYear().toString().slice(2, 4);
const epochDay = this.getDayOfYear_(currentDateObj);
const timeOfDay = (currentDateObj.getUTCHours() * 60 + currentDateObj.getUTCMinutes()) / 1440;
const epochDayStr = (epochDay + timeOfDay).toFixed(8).padStart(12, '0');
return {
epochYr: epochYear,
epochDay: epochDayStr,
};
}
getDayOfYear_(date) {
const dayCount = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
const mn = date.getUTCMonth();
const dn = date.getUTCDate();
let dayOfYear = dayCount[mn] + dn;
if (mn > 1 && this.isLeapYear_(date)) {
dayOfYear++;
}
return dayOfYear;
}
isLeapYear_(dateIn) {
const year = dateIn.getUTCFullYear();
if ((year & 3) !== 0) {
return false;
}
return year % 100 !== 0 || year % 400 === 0;
}
// / Convert to Julian date.
toJulianDate() {
return this.posix / secondsPerDay + 2440587.5;
}
// / Convert to Julian centuries.
toJulianCenturies() {
return (this.toJulianDate() - 2451545) / 36525;
}
// / Check if this is later than the [other] epoch.
operatorGreaterThan(other) {
return this.posix > other.posix;
}
// / Check if this is later or the same as the [other] epoch.
operatorGreaterThanOrEqual(other) {
return this.posix >= other.posix;
}
// / Check if this is earlier than the [other] epoch.
operatorLessThan(other) {
return this.posix < other.posix;
}
// / Check if this is earlier or the same as the [other] epoch.
operatorLessThanOrEqual(other) {
return this.posix <= other.posix;
}
}
//# sourceMappingURL=Epoch.js.map