astronomyengine (version 0.1.0)

astro_hour_angle: Calculate the hour angle of a body

Description

Finds the hour angle of a body for a given observer and time. The hour angle indicates the body's position in the sky with respect to Earth's rotation.

Usage

astro_hour_angle(body, time, latitude, longitude, height = 0)

Value

A numeric value representing the hour angle in the range [0, 24), where each unit is one sidereal hour.

Arguments

body

Integer body code (see astro_body).

time

A POSIXct date/time in UTC.

latitude

Observer's geographic latitude in degrees.

longitude

Observer's geographic longitude in degrees.

height

Observer's height above sea level in metres. Default 0.

Details

The hour angle is 0 when the body culminates (reaches its highest point), and increases by 1 unit for every sidereal hour that passes. A value of 12 means the body is at its lowest point. A value of 24 is equivalent to 0.

Examples

t <- as.POSIXct("2025-06-21 12:00:00", tz = "UTC")
astro_hour_angle(astro_body[["SUN"]], t,
                 latitude = -33.8688, longitude = 151.2093)