astro::earth::obliquity Namespace Reference

Functions
auto	mean (const double jde) -> toolbox::AngleDeg
	Calculates the mean obliquity of the ecliptic (ε₀) for the given julian day.
auto	true_obliquity (const double jde, const nutation::Model model=nutation::Model::IAU_1980) -> toolbox::AngleDeg
	Calculates the true obliquity of the ecliptic (ε) for the given julian day.

Function Documentation

mean()

auto astro::earth::obliquity::mean ( const double jde ) ->toolbox::AngleDeg

inlinenodiscard

Calculates the mean obliquity of the ecliptic (ε₀) for the given julian day.

Parameters

jde	The julian ephemeris day number, which is based on TT.

Returns

The mean obliquity (ε₀) in degrees.

Accuracy ~1" over ±2000 years from J2000; the polynomial degrades farther out. @see Jean Meeus, "Astronomical Algorithms", Second Edition, Chapter 22, Formula (22.2).

See also

ERFA v2.0.1 obl80.c.

true_obliquity()

auto astro::earth::obliquity::true_obliquity ( const double jde, const nutation::Model model = nutation::Model::IAU_1980 )->toolbox::AngleDeg

inlinenodiscard

Calculates the true obliquity of the ecliptic (ε) for the given julian day.

Parameters

jde	The julian ephemeris day number, which is based on TT.
model	The nutation model to use. Defaults to nutation::Model::IAU_1980.

Returns

The true obliquity (ε = ε₀ + Δε) in degrees.

See also

Jean Meeus, "Astronomical Algorithms", Second Edition, Chapter 22.