PN00 Subroutine

  1. astro_module.f90
  2. astro_module
  3. PN00

public subroutine PN00(date1, date2, dpsi, deps, epsa, rb, rp, rbp, rn, rbpn)

Precession-nutation, IAU 2000 model: a multi-purpose routine, supporting classical (equinox-based) use directly and CIO-based use indirectly.

Status: support routine.

Notes

  1. The TT date DATE1+DATE2 is a Julian Date, apportioned in any convenient way between the two arguments. For example, JD(TT)=2450123.7 could be expressed in any of these ways, among others:

        DATE1          DATE2

 2450123.7D0        0D0        (JD method)
  2451545D0      -1421.3D0     (J2000 method)
 2400000.5D0     50123.2D0     (MJD method)
 2450123.5D0       0.2D0       (date & time method)

    The JD method is the most natural and convenient to use in cases where the loss of several decimal digits of resolution is acceptable. The J2000 method is best matched to the way the argument is handled internally and will deliver the optimum resolution. The MJD method and the date & time methods are both good compromises between resolution and convenience.

  2. The caller is responsible for providing the nutation components; they are in longitude and obliquity, in radians and are with respect to the equinox and ecliptic of date. For high-accuracy applications, free core nutation should be included as well as any other relevant corrections to the position of the CIP.

  3. The returned mean obliquity is consistent with the IAU 2000 precession-nutation models.

  4. The matrix RB transforms vectors from GCRS to J2000.0 mean equator and equinox by applying frame bias.

  5. The matrix RP transforms vectors from J2000.0 mean equator and equinox to mean equator and equinox of date by applying precession.

  6. The matrix RBP transforms vectors from GCRS to mean equator and equinox of date by applying frame bias then precession. It is the product RP x RB.

  7. The matrix RN transforms vectors from mean equator and equinox of date to true equator and equinox of date by applying the nutation (luni-solar + planetary).

  8. The matrix RBPN transforms vectors from GCRS to true equator and equinox of date. It is the product RN x RBP, applying frame bias, precession and nutation in that order.

Reference

  • Capitaine, N., Chapront, J., Lambert, S. and Wallace, P., "Expressions for the Celestial Intermediate Pole and Celestial Ephemeris Origin consistent with the IAU 2000A precession-nutation model", Astron.Astrophys. 400, 1145-1154 (2003)

  • n.b. The celestial ephemeris origin (CEO) was renamed "celestial intermediate origin" (CIO) by IAU 2006 Resolution 2.

History

  • IAU SOFA revision: 2010 January 18

Arguments

TypeIntentOptionalAttributesName
real(kind=wp), intent(in) :: date1

TT as a 2-part Julian Date (Note 1)
real(kind=wp), intent(in) :: date2

TT as a 2-part Julian Date (Note 1)
real(kind=wp), intent(in) :: dpsi

nutation (Note 2)
real(kind=wp), intent(in) :: deps

nutation (Note 2)
real(kind=wp), intent(out) :: epsa

mean obliquity (Note 3)
real(kind=wp), intent(out), dimension(3,3):: rb

frame bias matrix (Note 4)
real(kind=wp), intent(out), dimension(3,3):: rp

precession matrix (Note 5)
real(kind=wp), intent(out), dimension(3,3):: rbp

bias-precession matrix (Note 6)
real(kind=wp), intent(out), dimension(3,3):: rn

nutation matrix (Note 7)
real(kind=wp), intent(out), dimension(3,3):: rbpn

GCRS-to-true matrix (Note 8)

Calls

proc~~pn00~~CallsGraph proc~pn00 PN00 proc~obl80 OBL80 proc~pn00->proc~obl80 proc~numat NUMAT proc~pn00->proc~numat proc~bp00 BP00 proc~pn00->proc~bp00 proc~rxr RXR proc~pn00->proc~rxr proc~pr00 PR00 proc~pn00->proc~pr00 proc~rx RX proc~numat->proc~rx proc~ir IR proc~numat->proc~ir proc~rz RZ proc~numat->proc~rz proc~bp00->proc~rxr proc~bp00->proc~pr00 proc~bp00->proc~rx proc~ry RY proc~bp00->proc~ry proc~bp00->proc~ir proc~bp00->proc~rz proc~bi00 BI00 proc~bp00->proc~bi00

Called by

proc~~pn00~~CalledByGraph proc~pn00 PN00 proc~pn00a PN00A proc~pn00a->proc~pn00 proc~pn00b PN00B proc~pn00b->proc~pn00 proc~c2tpe C2TPE proc~c2tpe->proc~pn00 proc~pnm00a PNM00A proc~pnm00a->proc~pn00a proc~num00a NUM00A proc~num00a->proc~pn00a proc~num00b NUM00B proc~num00b->proc~pn00b proc~pnm00b PNM00B proc~pnm00b->proc~pn00b proc~xys00a XYS00A proc~xys00a->proc~pnm00a proc~s00a S00A proc~s00a->proc~pnm00a proc~c2i00b C2I00B proc~c2i00b->proc~pnm00b proc~c2i00a C2I00A proc~c2i00a->proc~pnm00a proc~s00b S00B proc~s00b->proc~pnm00b proc~xys00b XYS00B proc~xys00b->proc~pnm00b proc~c2t00b C2T00B proc~c2t00b->proc~c2i00b proc~c2t00a C2T00A proc~c2t00a->proc~c2i00a

Contents

Source Code

PN00

Source Code

    subroutine PN00 ( date1, date2, dpsi, deps, &
                      epsa, rb, rp, rbp, rn, rbpn )

    implicit none

    real(wp),intent(in) :: date1 !! TT as a 2-part Julian Date (Note 1)
    real(wp),intent(in) :: date2 !! TT as a 2-part Julian Date (Note 1)
    real(wp),intent(in) :: dpsi !! nutation (Note 2)
    real(wp),intent(in) :: deps !! nutation (Note 2)
    real(wp),intent(out) :: epsa !! mean obliquity (Note 3)
    real(wp),dimension(3,3),intent(out) :: rb !! frame bias matrix (Note 4)
    real(wp),dimension(3,3),intent(out) :: rp !! precession matrix (Note 5)
    real(wp),dimension(3,3),intent(out) :: rbp !! bias-precession matrix (Note 6)
    real(wp),dimension(3,3),intent(out) :: rn !! nutation matrix (Note 7)
    real(wp),dimension(3,3),intent(out) :: rbpn !! GCRS-to-true matrix (Note 8)

    real(wp) :: dpsipr, depspr

    !  IAU 2000 precession-rate adjustments.
    call PR00 ( date1, date2, dpsipr, depspr )

    !  Mean obliquity, consistent with IAU 2000 precession-nutation.
    epsa = OBL80 ( date1, date2 ) + depspr

    !  Frame bias and precession matrices and their product.
    call BP00 ( date1, date2, rb, rp, rbp )

    !  Nutation matrix.
    call NUMAT ( epsa, dpsi, deps, rn )

    !  Bias-precession-nutation matrix (classical).
    call RXR ( rn, rbp, rbpn )

    end subroutine PN00