True Solar Time Calculator

A TypeScript utility for calculating True Solar Time and Equation of Time based on date and geographic coordinates (longitude, latitude).
计算真太阳时（True Solar Time）与时间均差（Equation of Time）的 TypeScript 工具库。

📦 Installation

npm install true-solar-time-calculator

or

bun add true-solar-time-calculator

🚀 Usage

import { TrueSolarTimeCalculator } from 'true-solar-time-calculator';

const localLongitude = 104.020721;
const localLatitude = 34.429150;
const now = new Date();

const calculator = new TrueSolarTimeCalculator(now, localLongitude, localLatitude);

console.log(`Input Date (UTC): ${calculator.utcDate.toISOString()}`);
console.log(`Longitude: ${calculator.longitude}°`);
console.log(`Latitude: ${calculator.latitude}°`);
console.log(`Julian Day: ${calculator.julianDay.toFixed(5)}`);
console.log(`Equation of Time: ${calculator.getHumanReadableEOT()}`);
console.log(`True Solar Time (ISO): ${calculator.trueSolarTime().getDate().toISOString()}`);
console.log(`True Solar Time (Formatted): ${calculator.trueSolarTime().format()}`);
console.log(`True Solar Time (HH:MM:SS): ${calculator.getTrueSolarTimeString()}`);

🛠 API

new TrueSolarTimeCalculator(inputDate: Date, longitude: number, latitude: number)

| Parameter | Type | Description | | ----------- | -------- | ---------------------------------------------- | | inputDate | Date | UTC date-time to calculate true solar time for | | longitude | number | Longitude in degrees (−180° to +180°) | | latitude | number | Latitude in degrees (−90° to +90°) |

Properties & Methods

| Method | Returns | Description | | ------------------------------- | -------- | -------------------------------------------------- | | utcDate | Date | The UTC input date | | julianDay | number | Julian Day number | | equationOfTimeSeconds | number | Equation of time in seconds | | getHumanReadableEOT() | string | Human-readable EOT (e.g., 2分30秒) | | trueSolarTime() | this | Computes true solar time (chainable) | | getDate() | Date | Date object of True Solar Time | | format(formatString?: string) | string | Formats TST date as string (YYYY-MM-DD HH:mm:ss) | | getTrueSolarTimeString() | string | Returns TST as HH:MM:SS |

📄 License

MIT © miharakinu