nare214/celmec

Calculate the real-time positions of the sun, all planets and every star/deep-sky object at the sky completely client-side

celmec

About

With this package, you can calculate the real-time positions of the sun, all planets and every star/deep-sky object at the sky completely client-side.

How to use

For stars

First, find the rotating equatorial coordinates of the star. They can be divided into two parts: right ascension (RA) and declination (Dec). You can look them up on wikipedia. It should look similar to this:

RA:  18h 37m 44.7s
Dec: 38° 48' 33.0"

Next, create a new instance of the Star class. Use RA and Dec of the star in degrees as parameters in the constructor. If the coordinates are given in hour angles or sexagesimal degrees, use new HourAngle(hours, minutes, seconds).toDegrees() or new SexagesimalDegrees(degrees, minutes, seconds).toDegrees().

   See also: Angle Units (Wikipedia)

Now, use RA and Dec (both in degrees) to create a new Star object:

const star = new Star(RA, Dec);

Finally, calculate azimuth and height. You'll need the geographic latitude and longitude.

const azimuthalPosition = star.calculateAzimuthal(latitude, longitude);
const azimuth = azimuthalPosition.azimuth;
const height = azimuthalPosition.height;

For planets

Create a new instance of the Planet class. In this example, it's Saturn, but you can use any planet from the object PlanetAbbreviation.

const saturn = new Planet(PlanetAbbreviation.sat);

Calculate azimuth and height by calling the method calculateAzimuthal(latitude, longitude):

const azimuthalPosition = saturn.calculateAzimuthal(latitude, longitude);
const azimuth = azimuthalPosition.azimuth;
const height = azimuthalPosition.height;

For the sun

Call Sun.calculateAzimuthal(latitude, longitude):

const azimuthalPosition = Sun.calculateAzimuthal(latitude, longitude);
const azimuth = azimuthalPosition.azimuth;
const height = azimuthalPosition.height;

NPM Package

https://www.npmjs.com/package/celmec