NUT06A Subroutine

  1. astro_module.f90
  2. astro_module
  3. NUT06A

public subroutine NUT06A(date1, date2, dpsi, deps)

IAU 2000A nutation with adjustments to match the IAU 2006 precession.

Status: canonical model.

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 in longitude and obliquity are in radians and with respect to the mean equinox and ecliptic of date, IAU 2006 precession model (Hilton et al. 2006, Capitaine et al. 2005).

  3. The routine first computes the IAU 2000A nutation, then applies adjustments for (i) the consequences of the change in obliquity from the IAU 1980 ecliptic to the IAU 2006 ecliptic and (ii) the secular variation in the Earth's dynamical form factor J2.

  4. The present routine provides classical nutation, complementing the IAU 2000 frame bias and IAU 2006 precession. It delivers a pole which is at current epochs accurate to a few tens of microarcseconds, apart from the free core nutation.

Reference

  • Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981

History

  • IAU SOFA revision: 2011 April 3

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, luni-solar + planetary (Note 2)
real(kind=wp), intent(out) :: deps

nutation, luni-solar + planetary (Note 2)

Calls

proc~~nut06a~~CallsGraph proc~nut06a NUT06A proc~nut00a NUT00A proc~nut06a->proc~nut00a 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

Called by

proc~~nut06a~~CalledByGraph proc~nut06a NUT06A proc~pnm06a PNM06A proc~pnm06a->proc~nut06a proc~num06a NUM06A proc~num06a->proc~nut06a proc~pn06a PN06A proc~pn06a->proc~nut06a proc~gst06a GST06A proc~gst06a->proc~pnm06a proc~s06a S06A proc~s06a->proc~pnm06a proc~xys06a XYS06A proc~xys06a->proc~pnm06a proc~c2i06a C2I06A proc~c2i06a->proc~pnm06a proc~apco13 APCO13 proc~apco13->proc~pnm06a proc~apci13 APCI13 proc~apci13->proc~pnm06a proc~eo06a EO06A proc~eo06a->proc~pnm06a proc~atco13 ATCO13 proc~atco13->proc~apco13 proc~atci13 ATCI13 proc~atci13->proc~apci13 proc~atic13 ATIC13 proc~atic13->proc~apci13 proc~ee06a EE06A proc~ee06a->proc~gst06a proc~c2t06a C2T06A proc~c2t06a->proc~c2i06a proc~atoc13 ATOC13 proc~atoc13->proc~apco13

Contents

Source Code

NUT06A

Source Code

    subroutine NUT06A ( date1, date2, dpsi, deps )

    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, luni-solar + planetary (Note 2)
    real(wp),intent(out) :: deps !! nutation, luni-solar + planetary (Note 2)

    !  Miscellaneous
    real(wp) :: t, fj2, dp, de

    !  Interval between fundamental date J2000.0 and given date (JC).
    t = ( ( date1-dj00 ) + date2 ) / djc

    !  Factor correcting for secular variation of J2.
    fj2 = -2.7774e-6_wp * t

    !  Obtain IAU 2000A nutation.
    call NUT00A ( date1, date2, dp, de )

    !  Apply P03 adjustments (Wallace & Capitaine, 2006, Eqs.5).
    dpsi = dp + dp * ( 0.4697e-6_wp + fj2 )
    deps = de + de * fj2

    end subroutine NUT06A