gcrsToEclipticOfDateIau2006 function

Vector3 gcrsToEclipticOfDateIau2006(
  1. Vector3 r,
  2. double t, {
  3. required double nutationInLongitude,
})

As gcrsToEclipticOfDate, with the IAU 2006 precession: the matrix R₁(−ε)·R₃(−ψ)·R₁(φ̄)·R₃(γ̄) of the IERS Conventions, section 5.4.5, without the final rotation R₁(−ε) (to the equator). Accurate only within about ±1000 years of J2000.

Implementation

Vector3 gcrsToEclipticOfDateIau2006(
  Vector3 r,
  double t, {
  required double nutationInLongitude,
}) {
  final fw = fukushimaWilliams(t);
  return r
      .rotateZ(fw.gamma)
      .rotateX(fw.phi)
      .rotateZ(-(fw.psi + nutationInLongitude));
}