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`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

. Returns the nutation in longitude
`jdtt`

and obliquity `dpsipr`

in radians with
respect to the J2000.0 equinox and ecliptic. The output variables get
the same dimensions as `depspr`

.
`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

can be
added to `dpsipr``psi_a`

, and

to both `depspr``omega_a`

and `eps_a`

.

See also: Astronomical Coordinate Calculations