solar-beam

General solar position calculator powered with TypeScript. The calculation is based on the spreadsheet from Earth System Research Laboratory.

DISCLAIMER: Please be mindful when using this library, as there is no guarantee that the values are valid. As written on the section "Data for Litigation":

The NOAA Solar Calculator is for research and recreational use only. NOAA cannot certify or authenticate sunrise, sunset or solar position data. The U.S. Government does not collect observations of astronomical data, and due to atmospheric conditions our calculated results may vary significantly from actual observed values.

Installation

# npm
npm install --save solar-beam

# yarn
yarn add solar-beam

Usage

import { getJulianDate } from 'solar-beam';

// May 5th, 2020, 12am o'clock, GMT +7.
const date = new Date(2020, 4, 9);
getJulianDate(date, -420); // 2458978.2083333335.

For more detailed information, please see the test file.

Available functions

Common utils

Function name	Parameter	Description
getJulianDate	(date: Date) => number	Returns the current Julian day

Fractions

Function name	Parameter	Description
getSolarNoonLSTInFractions	(params: MainFunctionParams) => number	Returns the solar noon time fraction from the given date and location
getSunriseInFractions	(params: MainFunctionParams) => number	Returns the sunrise time fraction from the given date and location
getSunsetInFractions	(params: MainFunctionParams) => number	Returns the sunset time fraction from the given date and location

Seconds

Function name	Parameter	Description
getSolarNoonLSTInSeconds	(params: MainFunctionParams) => number	Returns the solar noon seconds (of a day) from the given date and location
getSunriseInSeconds	(params: MainFunctionParams) => number	Returns the sunrise seconds (of a day) from the given date and location
getSunsetInSeconds	(params: MainFunctionParams) => number	Returns the sunset seconds (of a day) from the given date and location

Date

Function name	Parameter	Description
getSolarNoonLSTDate	(params: MainFunctionParams) => string	Returns the solar noon time in HH:mm:ss format from the given date and location
getSunriseDate	(params: MainFunctionParams) => string	Returns the sunrise time in HH:mm:ss format from the given date and location
getSunsetDate	(params: MainFunctionParams) => string	Returns the sunset time in HH:mm:ss format from the given date and location

Angles

Function name	Parameter	Description
getSolarElevationAngle	(params: MainFunctionParams) => number	Returns the solar elevation angle in degrees from the given date and location

Trying it locally

# Build first to generate the dist/ folder.
yarn build
# Run the example file.
node example/index.js

Testing

yarn test

Next updates

• [ ] Breakdown functions to separate folders. So, dist/ will contain index.js, index.min.js, and all other functions from src/. Hence, when browsers include it from <script> tag, they can access index.min.js directly, while users who want to use ESM can do, e.g. import getJulianDate from 'solar-beam/getJulianDate';.

LICENSE

MIT