PN00A Subroutine

  1. astro_module.f90
  2. astro_module
  3. PN00A

public subroutine PN00A(date1, date2, dpsi, deps, epsa, rb, rp, rbp, rn, rbpn)

Precession-nutation, IAU 2000A 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 nutation components (luni-solar + planetary, IAU 2000A) in longitude and obliquity are in radians and with respect to the equinox and ecliptic of date. Free core nutation is omitted; for the utmost accuracy, use the PN00 routine, where the nutation components are caller-specified. For faster but slightly less accurate results, use the PN00B routine.

  3. The mean obliquity is consistent with the IAU 2000 precession.

  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.

  9. The X,Y,Z coordinates of the IAU 2000A Celestial Intermediate Pole are elements (3,1-3) of the matrix RBPN.

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(out) :: dpsi

nutation (Note 2)
real(kind=wp), intent(out) :: 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 (Notes 8,9)

Calls

proc~~pn00a~~CallsGraph proc~pn00a PN00A proc~nut00a NUT00A proc~pn00a->proc~nut00a proc~pn00 PN00 proc~pn00a->proc~pn00 proc~faom03 FAOM03 proc~nut00a->proc~faom03 proc~faju03 FAJU03 proc~nut00a->proc~faju03 proc~fasa03 FASA03 proc~nut00a->proc~fasa03 proc~fae03 FAE03 proc~nut00a->proc~fae03 proc~fame03 FAME03 proc~nut00a->proc~fame03 proc~fal03 FAL03 proc~nut00a->proc~fal03 proc~fapa03 FAPA03 proc~nut00a->proc~fapa03 proc~faf03 FAF03 proc~nut00a->proc~faf03 proc~fave03 FAVE03 proc~nut00a->proc~fave03 proc~fama03 FAMA03 proc~nut00a->proc~fama03 proc~faur03 FAUR03 proc~nut00a->proc~faur03 proc~obl80 OBL80 proc~pn00->proc~obl80 proc~numat NUMAT proc~pn00->proc~numat proc~bp00 BP00 proc~pn00->proc~bp00 proc~pr00 PR00 proc~pn00->proc~pr00 proc~rxr RXR proc~pn00->proc~rxr proc~rx RX proc~numat->proc~rx proc~ir IR proc~numat->proc~ir proc~rz RZ proc~numat->proc~rz proc~bp00->proc~pr00 proc~bp00->proc~rxr 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~~pn00a~~CalledByGraph proc~pn00a PN00A proc~pnm00a PNM00A proc~pnm00a->proc~pn00a proc~num00a NUM00A proc~num00a->proc~pn00a proc~s00a S00A proc~s00a->proc~pnm00a proc~c2i00a C2I00A proc~c2i00a->proc~pnm00a proc~xys00a XYS00A proc~xys00a->proc~pnm00a proc~c2t00a C2T00A proc~c2t00a->proc~c2i00a

Contents

Source Code

PN00A

Source Code

    subroutine PN00A ( 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(out) :: dpsi !! nutation (Note 2)
    real(wp),intent(out) :: 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 (Notes 8,9)

    !  Nutation.
    call NUT00A ( date1, date2, dpsi, deps )

    !  Remaining results.
    call PN00 ( date1, date2, dpsi, deps, &
                    epsa, rb, rp, rbp, rn, rbpn )

    end subroutine PN00A