astronomyengine (version 0.1.0)

astro_equator: Topocentric equatorial coordinates of a celestial body

Description

Calculates equatorial coordinates of a celestial body as seen by an observer on Earth's surface.

Usage

astro_equator(
  body,
  time,
  latitude,
  longitude,
  height = 0,
  equdate = FALSE,
  aberration = TRUE
)

Value

A list with elements:

ra

Right ascension in sidereal hours.

dec

Declination in degrees.

dist

Distance in AU.

Arguments

body

Identifier of celestial body (e.g., astro_body[["SUN"]], astro_body[["MARS"]]). Must not be the Earth.

time

A POSIXct time value.

latitude

Observer's geographic latitude in degrees (positive north).

longitude

Observer's geographic longitude in degrees (positive east).

height

Observer's height in meters above sea level.

equdate

One of TRUE (true-equator-of-date) or FALSE (J2000). Default is FALSE.

aberration

One of TRUE (correct for aberration) or FALSE. Default is TRUE.

Details

This function corrects for light travel time and topocentric parallax (the angular shift depending on the observer's location on Earth). Parallax correction is most significant for the Moon but has a small effect on other bodies.

Examples

time <- as.POSIXct("2025-02-19 22:10:12", tz = "UTC")
astro_equator(astro_body[["MARS"]], time, latitude = -33.87, longitude = 151.21)