View Source Astrex.Astro.Refraction (Astrex v0.4.0)
Refraction can change significantly the apparent altitude of an object. The change depends solely on the altitude and is maximun on the horizon (objects may appear above the horizon when they are actually still below) and zero at the zenith
This module exports functions to calculate the true altitude given the apparent one, and to calculate the apparent altitude if the true one is known - typically calculated starting from equatorial coordinate system.
The algorithms are taken from Jean Meeus book: "Astronomical Algorithms" Chapter 16 - Atmospheric Refraction
Link to this section Summary
Functions
Receives a T.altazimuth map including the true altitude. Returns a T.altazimuth map including the apparent altitude.
Receives a T.altazimuth map including the apparent altitude Returns a T.altazimuth map including the true altitude
Link to this section Functions
@spec apparent_alt(Astrex.Types.altazimuth()) :: Astrex.Types.altazimuth()
Receives a T.altazimuth map including the true altitude. Returns a T.altazimuth map including the apparent altitude.
The true altitude is calculated from the equatorial coordinates of the object. The apparent altitude corresponds to where the digital setting circles must aim to center the object
examples
Examples
iex> Astrex.Astro.Refraction.apparent_alt(%{alt: 45, az: 180})
%{alt: 45.016878460981225, az: 180}
@spec true_alt(Astrex.Types.altazimuth()) :: Astrex.Types.altazimuth()
Receives a T.altazimuth map including the apparent altitude Returns a T.altazimuth map including the true altitude
The apparent altitude corresponds to the digital setting circles readings The true altitude allows to precisely calculate the equatorial coordinates of the point the telescope is aiming at.
examples
Examples
iex> Astrex.Astro.Refraction.true_alt(%{alt: 45, az: 180})
%{alt: 44.98341920053572, az: 180}