926eae349a
The function ParseArgs (used by many of the C demo programs) now allows an alternative command line usage. If the '-e' option is specified, it looks for the environment variable setting: ASTRONOMY_ENGINE_OBSERVER='latitude longitude' This form allows the demo programs to be configured for a given site.
Astronomy Engine examples in C
Culmination
Finds when the Sun, Moon, and planets reach their highest position in the sky on a given date, as seen by an observer at a specified location on the Earth. Culmination is also the moment a body crosses the meridian, the imaginary semicircle in the sky that passes from due north on the horizon, through the zenith (straight up), and then toward due south on the horizon.
Galactic to Horizontal Converter
A demonstration of how to convert galactic coordinates to horizontal coordinates. This could be useful for backyard radio astronomers who know the galactic coordinates of a distant radio source and want to aim a radio dish at it. Given the galactic coordinates, the geographic coordinates of the observer, and the date and time of the observation, this program shows how to obtain the altitude and azimuth to aim the dish at the radio source.
Horizon Intersection
This is a more advanced example. It shows how to use coordinate transforms to find where the ecliptic intersects with an observer's horizon at a given date and time.
Lunar Eclipse
Calculates details about the first 10 partial/total lunar eclipses after the given date and time.
Moon Phase Calculator
This example shows how to determine the Moon's current phase, and how to predict when the next few quarter phases will occur.
Positions
Calculates equatorial and horizontal coordinates of the Sun, Moon, and planets.
Rise/Set
Shows how to calculate sunrise, sunset, moonrise, and moonset times.
Seasons
Calculates the equinoxes and solstices for a given calendar year.
Triangulate
Given the geographic coordinates of two observers, and angular
directions they are looking in, determines geographic coordinates
of the point they are both looking at. This example demonstrates
use of the geoid functions VectorObserver and ObserverVector
that convert between geographic coordinates and vectors.
API Reference
Complete documentation for all the functions and types available in the C version of Astronomy Engine.