IauRotationModel
Defined in: rotation.rs:39
pub struct IauRotationModel { pub alpha0: f64, pub alpha1: f64, pub delta0: f64, pub delta1: f64, pub w0: f64, pub wd: f64,}IAU rotation model parameters for a celestial body.
The north pole direction (right ascension α, declination δ) and prime meridian angle W are given as linear functions of time:
α = α₀ + α₁ T [degrees] δ = δ₀ + δ₁ T [degrees] W = W₀ + W_d d [degrees]
where T = Julian centuries since J2000, d = Julian days since J2000.
Fields
Section titled “Fields”alpha0
Section titled “alpha0”alpha0: f64
Right ascension of north pole at J2000 [deg]
alpha1
Section titled “alpha1”alpha1: f64
Rate of right ascension per Julian century [deg/century]
delta0
Section titled “delta0”delta0: f64
Declination of north pole at J2000 [deg]
delta1
Section titled “delta1”delta1: f64
Rate of declination per Julian century [deg/century]
w0: f64
Prime meridian angle at J2000 [deg]
wd: f64
Prime meridian rate [deg/day]
Methods
Section titled “Methods”orientation()
Section titled “orientation()”fn orientation(&self, epoch: &[Epoch<Tdb>](../epoch/)) -> UnitQuaternion<f64>
Compute the body-fixed → ECI (J2000) unit quaternion at the given epoch.
The returned quaternion transforms vectors from the body-fixed frame (Z = north pole, X = prime meridian) to the ECI/ICRF frame.
Takes &Epoch<Tdb> — IAU WGCCRE 2009 (Archinal et al. 2011) defines the
independent variable as “interval in Julian days from J2000 in TDB”.
prime_meridian_angle()
Section titled “prime_meridian_angle()”fn prime_meridian_angle(&self, epoch: &[Epoch<Tdb>](../epoch/)) -> f64
Compute the prime meridian angle W at the given epoch [radians].
pole_direction()
Section titled “pole_direction()”fn pole_direction(&self, epoch: &[Epoch<Tdb>](../epoch/)) -> Vector3<f64>
Compute the north pole direction in ECI at the given epoch.