PVTOB Subroutine

  1. astro_module.f90
  2. astro_module
  3. PVTOB

public subroutine PVTOB(elong, phi, hm, xp, yp, sp, theta, pv)

Position and velocity of a terrestrial observing station.

Status: support routine.

Notes

  1. The terrestrial coordinates are with respect to the WGS84 reference ellipsoid.

  2. XP and YP are the coordinates (in radians) of the Celestial Intermediate Pole with respect to the International Terrestrial Reference System (see IERS Conventions 2003), measured along the meridians 0 and 90 deg west respectively. SP is the TIO locator s', in radians, which positions the Terrestrial Intermediate Origin on the equator. For many applications, XP, YP and (especially) SP can be set to zero.

  3. If THETA is Greenwich apparent sidereal time instead of Earth rotation angle, the result is with respect to the true equator and equinox of date, i.e. with the x-axis at the equinox rather than the celestial intermediate origin.

  4. The velocity units are meters per UT1 second, not per SI second. This is unlikely to have any practical consequences in the modern era.

  5. No validation is performed on the arguments. Error cases that could lead to arithmetic exceptions are trapped by the GD2GC routine, and the result set to zeros.

References

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

  • Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to the Astronomical Almanac, 3rd ed., University Science Books (2013), Section 7.4.3.3.

History

  • IAU SOFA revision: 2013 June 25

Arguments

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

longitude (radians, east +ve, Note 1)
real(kind=wp), intent(in) :: phi

latitude (geodetic, radians, Note 1)
real(kind=wp), intent(in) :: hm

height above reference ellipsoid (geodetic, m)
real(kind=wp), intent(in) :: xp

coordinates of the pole (radians, Note 2)
real(kind=wp), intent(in) :: yp

coordinates of the pole (radians, Note 2)
real(kind=wp), intent(in) :: sp

the TIO locator s' (radians, Note 2)
real(kind=wp), intent(in) :: theta

Earth rotation angle (radians, Note 3)
real(kind=wp), intent(out), dimension(3,2):: pv

position/velocity vector (m, m/s, CIRS)

Calls

proc~~pvtob~~CallsGraph proc~pvtob PVTOB proc~gd2gc GD2GC proc~pvtob->proc~gd2gc proc~pom00 POM00 proc~pvtob->proc~pom00 proc~trxp TRXP proc~pvtob->proc~trxp proc~gd2gce GD2GCE proc~gd2gc->proc~gd2gce proc~zp ZP proc~gd2gc->proc~zp proc~eform EFORM proc~gd2gc->proc~eform proc~rx RX proc~pom00->proc~rx proc~ry RY proc~pom00->proc~ry proc~ir IR proc~pom00->proc~ir proc~rz RZ proc~pom00->proc~rz proc~rxp RXP proc~trxp->proc~rxp proc~tr TR proc~trxp->proc~tr

Called by

proc~~pvtob~~CalledByGraph proc~pvtob PVTOB proc~apco APCO proc~apco->proc~pvtob proc~apio APIO proc~apio->proc~pvtob proc~apco13 APCO13 proc~apco13->proc~apco proc~apio13 APIO13 proc~apio13->proc~apio proc~atco13 ATCO13 proc~atco13->proc~apco13 proc~atoi13 ATOI13 proc~atoi13->proc~apio13 proc~atio13 ATIO13 proc~atio13->proc~apio13 proc~atoc13 ATOC13 proc~atoc13->proc~apco13

Contents

Source Code

PVTOB

Source Code

    subroutine PVTOB ( elong, phi, hm, xp, yp, sp, theta, pv )

    implicit none

    real(wp),intent(in) :: elong !! longitude (radians, east +ve, Note 1)
    real(wp),intent(in) :: phi !! latitude (geodetic, radians, Note 1)
    real(wp),intent(in) :: hm !! height above reference ellipsoid (geodetic, m)
    real(wp),intent(in) :: xp !! coordinates of the pole (radians, Note 2)
    real(wp),intent(in) :: yp !! coordinates of the pole (radians, Note 2)
    real(wp),intent(in) :: sp !! the TIO locator s' (radians, Note 2)
    real(wp),intent(in) :: theta !! Earth rotation angle (radians, Note 3)
    real(wp),dimension(3,2),intent(out) :: pv !! position/velocity vector (m, m/s, CIRS)

    !  Earth rotation rate in radians per UT1 second
    real(wp),parameter :: om = 1.00273781191135448_wp * d2pi / d2s

    integer :: j
    real(wp) :: xyzm(3), rpm(3,3), xyz(3), x, y, z, s, c

    !  Geodetic to geocentric transformation (WGS84).
    call GD2GC ( 1, elong, phi, hm, xyzm, j )

    !  Polar motion and TIO position.
    call POM00 ( xp, yp, sp, rpm )
    call TRXP ( rpm, xyzm, xyz )
    x = xyz(1)
    y = xyz(2)
    z = xyz(3)

    !  routines of ERA.
    s = sin(theta)
    c = cos(theta)

    !  Position.
    pv(1,1) = c*x - s*y
    pv(2,1) = s*x + c*y
    pv(3,1) = z

    !  Velocity.
    pv(1,2) = om * ( -s*x - c*y )
    pv(2,2) = om * (  c*x - s*y )
    pv(3,2) = 0.0_wp

    end subroutine PVTOB