ATCI13 Subroutine

  1. astro_module.f90
  2. astro_module
  3. ATCI13

public subroutine ATCI13(rc, dc, pr, pd, px, rv, date1, date2, ri, di, eo)

Transform ICRS star data, epoch J2000.0, to CIRS.

Status: support routine.

Notes

  1. Star data for an epoch other than J2000.0 (for example from the Hipparcos catalog, which has an epoch of J1991.25) will require a preliminary call to PMSAFE before use.

  2. The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.

  3. The TDB date DATE1+DATE2 is a Julian Date, apportioned in any convenient way between the two arguments. For example, JD(TDB)=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. For most applications of this routine the choice will not be at all critical.

    TT can be used instead of TDB without any significant impact on accuracy.

  4. The available accuracy is better than 1 milliarcsecond, limited mainly by the precession-nutation model that is used, namely IAU 2000A/2006. Very close to solar system bodies, additional errors of up to several milliarcseconds can occur because of unmodeled light deflection; however, the Sun's contribution is taken into account, to first order. The accuracy limitations of the SOFA routine EPV00 (used to compute Earth position and velocity) can contribute aberration errors of up to 5 microarcseconds. Light deflection at the Sun's limb is uncertain at the 0.4 mas level.

  5. Should the transformation to (equinox based) apparent place be required rather than (CIO based) intermediate place, subtract the equation of the origins from the returned right ascension: RA = RI - EO. (The ANP routine can then be applied, as required, to keep the result in the conventional 0-2pi range.)

History

  • IAU SOFA revision: 2017 March 12

Arguments

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

ICRS right ascension at J2000.0 (radians, Note 1)
real(kind=wp), intent(in) :: dc

ICRS declination at J2000.0 (radians, Note 1)
real(kind=wp), intent(in) :: pr

RA proper motion (radians/year; Note 2)
real(kind=wp), intent(in) :: pd

Dec proper motion (radians/year)
real(kind=wp), intent(in) :: px

parallax (arcsec)
real(kind=wp), intent(in) :: rv

radial velocity (km/s, +ve if receding)
real(kind=wp), intent(in) :: date1

TDB as a 2-part...
real(kind=wp), intent(in) :: date2
real(kind=wp), intent(out) :: ri

CIRS geocentric RA (radians)
real(kind=wp), intent(out) :: di

CIRS geocentric Dec (radians)
real(kind=wp), intent(out) :: eo

equation of the origins (ERA-GST, Note 5)

Calls

proc~~atci13~~CallsGraph proc~atci13 ATCI13 proc~apci13 APCI13 proc~atci13->proc~apci13 proc~atciq ATCIQ proc~atci13->proc~atciq proc~s06 S06 proc~apci13->proc~s06 proc~pnm06a PNM06A proc~apci13->proc~pnm06a proc~eors EORS proc~apci13->proc~eors proc~apci APCI proc~apci13->proc~apci proc~epv00 EPV00 proc~apci13->proc~epv00 proc~bpn2xy BPN2XY proc~apci13->proc~bpn2xy proc~pmpx PMPX proc~atciq->proc~pmpx proc~c2s C2S proc~atciq->proc~c2s proc~rxp RXP proc~atciq->proc~rxp proc~ab AB proc~atciq->proc~ab proc~ldsun LDSUN proc~atciq->proc~ldsun proc~anp ANP proc~atciq->proc~anp 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~pfw06 PFW06 proc~pnm06a->proc~pfw06 proc~nut06a NUT06A proc~pnm06a->proc~nut06a proc~fw2m FW2M proc~pnm06a->proc~fw2m proc~pdp PDP proc~pmpx->proc~pdp proc~ab->proc~pdp proc~c2ixys C2IXYS proc~apci->proc~c2ixys proc~apcg APCG proc~apci->proc~apcg proc~ld LD proc~ldsun->proc~ld proc~obl06 OBL06 proc~pfw06->proc~obl06 proc~ry RY proc~c2ixys->proc~ry proc~ir IR proc~c2ixys->proc~ir proc~rz RZ proc~c2ixys->proc~rz proc~nut00a NUT00A proc~nut06a->proc~nut00a proc~rx RX proc~fw2m->proc~rx proc~fw2m->proc~ir proc~fw2m->proc~rz proc~zpv ZPV proc~apcg->proc~zpv proc~apcs APCS proc~apcg->proc~apcs proc~ld->proc~pdp proc~pxp PXP proc~ld->proc~pxp 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 proc~zp ZP proc~zpv->proc~zp proc~apcs->proc~ir proc~pn PN proc~apcs->proc~pn proc~pn->proc~zp proc~sxp SXP proc~pn->proc~sxp

Contents

Source Code

ATCI13

Source Code

    subroutine ATCI13 ( rc, dc, pr, pd, px, rv, date1, date2, &
                        ri, di, eo )

    implicit none

    real(wp),intent(in) :: rc !! ICRS right ascension at J2000.0 (radians, Note 1)
    real(wp),intent(in) :: dc !! ICRS declination at J2000.0 (radians, Note 1)
    real(wp),intent(in) :: pr !! RA proper motion (radians/year; Note 2)
    real(wp),intent(in) :: pd !! Dec proper motion (radians/year)
    real(wp),intent(in) :: px !! parallax (arcsec)
    real(wp),intent(in) :: rv !! radial velocity (km/s, +ve if receding)
    real(wp),intent(in) :: date1 !! TDB as a 2-part...
    real(wp),intent(in) :: date2 !! ...Julian Date (Note 3)
    real(wp),intent(out) :: ri !! CIRS geocentric RA (radians)
    real(wp),intent(out) :: di !! CIRS geocentric Dec (radians)
    real(wp),intent(out) :: eo !! equation of the origins (ERA-GST, Note 5)

    !  Star-independent astrometry parameters
    real(wp) :: astrom(30)

    !  The transformation parameters.
    call APCI13 ( date1, date2, astrom, eo )

    !  ICRS (epoch J2000.0) to CIRS.
    call ATCIQ ( rc, dc, pr, pd, px, rv, astrom, ri, di )

    end subroutine ATCI13