fk52h.c

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#include "erfa.h"

void eraFk52h(double r5, double d5,
              double dr5, double dd5, double px5, double rv5,
              double *rh, double *dh,
              double *drh, double *ddh, double *pxh, double *rvh)
/*
**  - - - - - - - - -
**   e r a F k 5 2 h
**  - - - - - - - - -
**
**  Transform FK5 (J2000.0) star data into the Hipparcos system.
**
**  Given (all FK5, equinox J2000.0, epoch J2000.0):
**     r5      double    RA (radians)
**     d5      double    Dec (radians)
**     dr5     double    proper motion in RA (dRA/dt, rad/Jyear)
**     dd5     double    proper motion in Dec (dDec/dt, rad/Jyear)
**     px5     double    parallax (arcsec)
**     rv5     double    radial velocity (km/s, positive = receding)
**
**  Returned (all Hipparcos, epoch J2000.0):
**     rh      double    RA (radians)
**     dh      double    Dec (radians)
**     drh     double    proper motion in RA (dRA/dt, rad/Jyear)
**     ddh     double    proper motion in Dec (dDec/dt, rad/Jyear)
**     pxh     double    parallax (arcsec)
**     rvh     double    radial velocity (km/s, positive = receding)
**
**  Notes:
**
**  1) This function transforms FK5 star positions and proper motions
**     into the system of the Hipparcos catalog.
**
**  2) The proper motions in RA are dRA/dt rather than
**     cos(Dec)*dRA/dt, and are per year rather than per century.
**
**  3) The FK5 to Hipparcos transformation is modeled as a pure
**     rotation and spin;  zonal errors in the FK5 catalog are not
**     taken into account.
**
**  4) See also eraH2fk5, eraFk5hz, eraHfk5z.
**
**  Called:
**     eraStarpv    star catalog data to space motion pv-vector
**     eraFk5hip    FK5 to Hipparcos rotation and spin
**     eraRxp       product of r-matrix and p-vector
**     eraPxp       vector product of two p-vectors
**     eraPpp       p-vector plus p-vector
**     eraPvstar    space motion pv-vector to star catalog data
**
**  Reference:
**
**     F.Mignard & M.Froeschle, Astron. Astrophys. 354, 732-739 (2000).
**
**  Copyright (C) 2013-2015, NumFOCUS Foundation.
**  Derived, with permission, from the SOFA library.  See notes at end of file.
*/
{
   int i;
   double pv5[2][3], r5h[3][3], s5h[3], wxp[3], vv[3], pvh[2][3];

/* FK5 barycentric position/velocity pv-vector (normalized). */
   eraStarpv(r5, d5, dr5, dd5, px5, rv5, pv5);

/* FK5 to Hipparcos orientation matrix and spin vector. */
   eraFk5hip(r5h, s5h);

/* Make spin units per day instead of per year. */
   for ( i = 0; i < 3; s5h[i++] /= 365.25 );

/* Orient the FK5 position into the Hipparcos system. */
   eraRxp(r5h, pv5[0], pvh[0]);

/* Apply spin to the position giving an extra space motion component. */
   eraPxp(pv5[0], s5h, wxp);

/* Add this component to the FK5 space motion. */
   eraPpp(wxp, pv5[1], vv);

/* Orient the FK5 space motion into the Hipparcos system. */
   eraRxp(r5h, vv, pvh[1]);

/* Hipparcos pv-vector to spherical. */
   eraPvstar(pvh, rh, dh, drh, ddh, pxh, rvh);

   return;

}
/*----------------------------------------------------------------------
**  
**  
**  Copyright (C) 2013-2015, NumFOCUS Foundation.
**  All rights reserved.
**  
**  This library is derived, with permission, from the International
**  Astronomical Union's "Standards of Fundamental Astronomy" library,
**  available from http://www.iausofa.org.
**  
**  The ERFA version is intended to retain identical functionality to
**  the SOFA library, but made distinct through different function and
**  file names, as set out in the SOFA license conditions.  The SOFA
**  original has a role as a reference standard for the IAU and IERS,
**  and consequently redistribution is permitted only in its unaltered
**  state.  The ERFA version is not subject to this restriction and
**  therefore can be included in distributions which do not support the
**  concept of "read only" software.
**  
**  Although the intent is to replicate the SOFA API (other than
**  replacement of prefix names) and results (with the exception of
**  bugs;  any that are discovered will be fixed), SOFA is not
**  responsible for any errors found in this version of the library.
**  
**  If you wish to acknowledge the SOFA heritage, please acknowledge
**  that you are using a library derived from SOFA, rather than SOFA
**  itself.
**  
**  
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