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15.5.456 pr00

pr00, jdtt, dpsipr, depspr

[SOFA] Returns the precession-rate part of the IAU 2000 precession-nutation models (part of MHB2000), for the specified TT Julian Date jdtt. Returns the nutation in longitude dpsipr and obliquity depspr in radians with respect to the J2000.0 equinox and ecliptic. The output variables get the same dimensions as jdtt.

The MHB2000 model does not specify which set of Euler angles to use to express precession. The most literal and straightforward procedure is to adopt the 4-rotation epsilon_0, psi_a, omega_a, and xi_a. Then dpsipr can be added to psi_a, and depspr to both omega_a and eps_a.

See also: Astronomical Coordinate Calculations