C2I06A Subroutine

  1. astro_module.f90
  2. astro_module
  3. C2I06A

public subroutine C2I06A(date1, date2, rc2i)

Form the celestial-to-intermediate matrix for a given date using the IAU 2006 precession and IAU 2000A nutation models.

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 matrix RC2I is the first stage in the transformation from celestial to terrestrial coordinates:

    [TRS]  =  RPOM * R_3(ERA) * RC2I * [CRS]

       =  RC2T * [CRS]

    where [CRS] is a vector in the Geocentric Celestial Reference System and [TRS] is a vector in the International Terrestrial Reference System (see IERS Conventions 2003), ERA is the Earth Rotation Angle and RPOM is the polar motion matrix.

References

  • McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003), IERS Technical Note No. 32, BKG

  • Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855

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

History

  • IAU SOFA revision: 2007 May 11

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), dimension(3,3):: rc2i

celestial-to-intermediate matrix (Note 2)

Calls

proc~~c2i06a~~CallsGraph proc~c2i06a C2I06A proc~pnm06a PNM06A proc~c2i06a->proc~pnm06a proc~c2ixys C2IXYS proc~c2i06a->proc~c2ixys proc~s06 S06 proc~c2i06a->proc~s06 proc~bpn2xy BPN2XY proc~c2i06a->proc~bpn2xy proc~pfw06 PFW06 proc~pnm06a->proc~pfw06 proc~nut06a NUT06A proc~pnm06a->proc~nut06a proc~fw2m FW2M proc~pnm06a->proc~fw2m proc~ry RY proc~c2ixys->proc~ry proc~ir IR proc~c2ixys->proc~ir proc~rz RZ proc~c2ixys->proc~rz proc~faom03 FAOM03 proc~s06->proc~faom03 proc~falp03 FALP03 proc~s06->proc~falp03 proc~fae03 FAE03 proc~s06->proc~fae03 proc~fal03 FAL03 proc~s06->proc~fal03 proc~faf03 FAF03 proc~s06->proc~faf03 proc~fad03 FAD03 proc~s06->proc~fad03 proc~fave03 FAVE03 proc~s06->proc~fave03 proc~fapa03 FAPA03 proc~s06->proc~fapa03 proc~obl06 OBL06 proc~pfw06->proc~obl06 proc~nut00a NUT00A proc~nut06a->proc~nut00a proc~fw2m->proc~ir proc~fw2m->proc~rz proc~rx RX proc~fw2m->proc~rx proc~nut00a->proc~faom03 proc~nut00a->proc~fae03 proc~nut00a->proc~fal03 proc~nut00a->proc~faf03 proc~nut00a->proc~fave03 proc~nut00a->proc~fapa03 proc~fame03 FAME03 proc~nut00a->proc~fame03 proc~fasa03 FASA03 proc~nut00a->proc~fasa03 proc~faju03 FAJU03 proc~nut00a->proc~faju03 proc~fama03 FAMA03 proc~nut00a->proc~fama03 proc~faur03 FAUR03 proc~nut00a->proc~faur03

Called by

proc~~c2i06a~~CalledByGraph proc~c2i06a C2I06A proc~c2t06a C2T06A proc~c2t06a->proc~c2i06a

Contents

Source Code

C2I06A

Source Code

    subroutine C2I06A ( date1, date2, rc2i )

    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),dimension(3,3),intent(out) :: rc2i !! celestial-to-intermediate matrix (Note 2)

    real(wp) :: rbpn(3,3), x, y, s

    !  Obtain the celestial-to-true matrix (IAU 2006/2000A).
    call PNM06A ( date1, date2, rbpn )

    !  Extract the X,Y coordinates.
    call BPN2XY ( rbpn, x, y )

    !  Obtain the CIO locator.
    s = S06 ( date1, date2, x, y )

    !  Form the celestial-to-intermediate matrix.
    call C2IXYS ( x, y, s, rc2i )

    end subroutine C2I06A