BI00 Subroutine

  1. astro_module.f90
  2. astro_module
  3. BI00

public subroutine BI00(dpsibi, depsbi, dra)

Frame bias components of IAU 2000 precession-nutation models (part of MHB2000 with additions).

Status: canonical model.

Notes

  1. The frame bias corrections in longitude and obliquity (radians) are required in order to correct for the offset between the GCRS pole and the J2000.0 mean pole. They define, with respect to the GCRS frame, a J2000.0 mean pole that is consistent with the rest of the IAU 2000A precession-nutation model.

  2. In addition to the displacement of the pole, the complete description of the frame bias requires also an offset in right ascension. This is not part of the IAU 2000A model, and is from Chapront et al. (2002). It is returned in radians.

  3. This is a supplemented implementation of one aspect of the IAU 2000A nutation model, formally adopted by the IAU General Assembly in 2000, namely MHB2000 (Mathews et al. 2002).

References

  • Chapront, J., Chapront-Touze, M. & Francou, G., Astron.Astrophys., 387, 700, 2002.

  • Mathews, P.M., Herring, T.A., Buffet, B.A., "Modeling of nutation and precession New nutation series for nonrigid Earth and insights into the Earth's interior", J.Geophys.Res., 107, B4,

    1. The MHB2000 code itself was obtained on 9th September 2002 from ftp://maia.usno.navy.mil/conv2000/chapter5/IAU2000A.

History

  • IAU SOFA revision: 2009 December 15

Arguments

TypeIntentOptionalAttributesName
real(kind=wp), intent(out) :: dpsibi

longitude correction
real(kind=wp), intent(out) :: depsbi

obliquity correction
real(kind=wp), intent(out) :: dra

the ICRS RA of the J2000.0 mean equinox

Called by

proc~~bi00~~CalledByGraph proc~bi00 BI00 proc~bp00 BP00 proc~bp00->proc~bi00 proc~pn00 PN00 proc~pn00->proc~bp00 proc~pmat00 PMAT00 proc~pmat00->proc~bp00 proc~pn00a PN00A proc~pn00a->proc~pn00 proc~pn00b PN00B proc~pn00b->proc~pn00 proc~c2tpe C2TPE proc~c2tpe->proc~pn00 proc~pnm00a PNM00A proc~pnm00a->proc~pn00a proc~num00a NUM00A proc~num00a->proc~pn00a proc~num00b NUM00B proc~num00b->proc~pn00b proc~pnm00b PNM00B proc~pnm00b->proc~pn00b proc~xys00a XYS00A proc~xys00a->proc~pnm00a proc~s00a S00A proc~s00a->proc~pnm00a proc~c2i00b C2I00B proc~c2i00b->proc~pnm00b proc~c2i00a C2I00A proc~c2i00a->proc~pnm00a proc~s00b S00B proc~s00b->proc~pnm00b proc~xys00b XYS00B proc~xys00b->proc~pnm00b proc~c2t00b C2T00B proc~c2t00b->proc~c2i00b proc~c2t00a C2T00A proc~c2t00a->proc~c2i00a

Contents

Source Code

BI00

Source Code

    subroutine BI00 ( dpsibi, depsbi, dra )

    implicit none

    real(wp),intent(out) :: dpsibi !! longitude correction
    real(wp),intent(out) :: depsbi !! obliquity correction
    real(wp),intent(out) :: dra !! the ICRS RA of the J2000.0 mean equinox

    !  The frame bias corrections in longitude and obliquity
    real(wp),parameter :: dpbias = -0.041775_wp * das2r
    real(wp),parameter :: debias = -0.0068192_wp * das2r

    !  The ICRS RA of the J2000.0 equinox (Chapront et al., 2002)
    real(wp),parameter :: dra0 = -0.0146_wp * das2r

    !  Return the results (which are fixed).
    dpsibi = dpbias
    depsbi = debias
    dra = dra0

    end subroutine BI00