PN00B Subroutine

  1. astro_module.f90
  2. astro_module
  3. PN00B

public subroutine PN00B(date1, date2, dpsi, deps, epsa, rb, rp, rbp, rn, rbpn)

Precession-nutation, IAU 2000B 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 2000B) in longitude and obliquity are in radians and with respect to the equinox and ecliptic of date. For more accurate results, but at the cost of increased computation, use the PN00A routine. For the utmost accuracy, use the PN00 routine, where the nutation components are caller-specified.

  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 2000B 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~~pn00b~~CallsGraph proc~pn00b PN00B proc~nut00b NUT00B proc~pn00b->proc~nut00b proc~pn00 PN00 proc~pn00b->proc~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~~pn00b~~CalledByGraph proc~pn00b PN00B proc~pnm00b PNM00B proc~pnm00b->proc~pn00b proc~num00b NUM00B proc~num00b->proc~pn00b proc~s00b S00B proc~s00b->proc~pnm00b proc~c2i00b C2I00B proc~c2i00b->proc~pnm00b proc~xys00b XYS00B proc~xys00b->proc~pnm00b proc~c2t00b C2T00B proc~c2t00b->proc~c2i00b

Contents

Source Code

PN00B

Source Code

    subroutine PN00B ( 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 NUT00B ( date1, date2, dpsi, deps )

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

    end subroutine PN00B