PNM80 Subroutine

  1. astro_module.f90
  2. astro_module
  3. PNM80

public subroutine PNM80(date1, date2, rmatpn)

Form the matrix of precession/nutation for a given date, IAU 1976 precession model, IAU 1980 nutation model.

Status: support routine.

Notes

  1. The TDB date DATE1+DATE2 is a Julian Date, apportioned in any convenient way between the two arguments. For example, JD(TDB)=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 matrix operates in the sense V(date) = RMATPN * V(J2000), where the p-vector V(date) is with respect to the true equatorial triad of date DATE1+DATE2 and the p-vector V(J2000) is with respect to the mean equatorial triad of epoch J2000.0.

Reference

  • Explanatory Supplement to the Astronomical Almanac, P. Kenneth Seidelmann (ed), University Science Books (1992), Section 3.3 (p145).

History

  • IAU SOFA revision: 2012 September 5

Arguments

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

TDB date (Note 1)
real(kind=wp), intent(in) :: date2

TDB date (Note 1)
real(kind=wp), intent(out), dimension(3,3):: rmatpn

combined precession/nutation matrix

Calls

proc~~pnm80~~CallsGraph proc~pnm80 PNM80 proc~pmat76 PMAT76 proc~pnm80->proc~pmat76 proc~rxr RXR proc~pnm80->proc~rxr proc~nutm80 NUTM80 proc~pnm80->proc~nutm80 proc~ry RY proc~pmat76->proc~ry proc~prec76 PREC76 proc~pmat76->proc~prec76 proc~ir IR proc~pmat76->proc~ir proc~rz RZ proc~pmat76->proc~rz proc~obl80 OBL80 proc~nutm80->proc~obl80 proc~numat NUMAT proc~nutm80->proc~numat proc~nut80 NUT80 proc~nutm80->proc~nut80 proc~numat->proc~ir proc~numat->proc~rz proc~rx RX proc~numat->proc~rx proc~anpm ANPM proc~nut80->proc~anpm

Contents

Source Code

PNM80

Source Code

    subroutine PNM80 ( date1, date2, rmatpn )

    implicit none

    real(wp),intent(in) :: date1 !! TDB date (Note 1)
    real(wp),intent(in) :: date2 !! TDB date (Note 1)
    real(wp),dimension(3,3),intent(out) :: rmatpn !! combined precession/nutation matrix

    real(wp) :: rmatp(3,3), rmatn(3,3)

    !  Precession matrix, J2000.0 to date.
    call PMAT76 ( date1, date2, rmatp )

    !  Nutation matrix.
    call NUTM80 ( date1, date2, rmatn )

    !  Combine the matrices:  PN = N x P.
    call RXR ( rmatn, rmatp, rmatpn )

    end subroutine PNM80