astronomy

//astronomy/io.github.cosinekitty.astronomy/Vector/toHorizontal

toHorizontal

fun toHorizontal(refraction: Refraction): Spherical

Converts Cartesian coordinates to horizontal coordinates.

Given a horizontal Cartesian vector, returns horizontal azimuth and altitude. IMPORTANT: This function differs from Vector.toSpherical in two ways:

• toSpherical returns a lon value that represents azimuth defined counterclockwise from north (e.g., west = +90), but this function represents a clockwise rotation (e.g., east = +90). The difference is because toSpherical is intended to preserve the vector “right-hand rule”, while this function defines azimuth in a more traditional way as used in navigation and cartography.
• This function optionally corrects for atmospheric refraction, while toSpherical does not.

The returned object contains the azimuth in lon. It is measured in degrees clockwise from north: east = +90 degrees, west = +270 degrees.

The altitude is stored in lat.

The distance to the observed object is stored in dist, and is expressed in astronomical units (AU).

Parameters

refraction	Refraction.None: no atmospheric refraction correction is performed. Refraction.Normal: correct altitude for atmospheric refraction. Refraction.JplHor: for JPL Horizons compatibility testing only; not recommended for normal use.

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