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slalib/h2fk5.f

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+      SUBROUTINE sla_H2FK5 (RH,DH,DRH,DDH,R5,D5,DR5,DD5)
+*+
+*     - - - - - -
+*      H 2 F K 5
+*     - - - - - -
+*
+*  Transform Hipparcos star data into the FK5 (J2000) system.
+*
+*  (double precision)
+*
+*  This routine transforms Hipparcos star positions and proper
+*  motions into FK5 J2000.
+*
+*  Given (all Hipparcos, epoch J2000):
+*     RH        d      RA (radians)
+*     DH        d      Dec (radians)
+*     DRH       d      proper motion in RA (dRA/dt, rad/Jyear)
+*     DDH       d      proper motion in Dec (dDec/dt, rad/Jyear)
+*
+*  Returned (all FK5, equinox J2000, epoch J2000):
+*     R5        d      RA (radians)
+*     D5        d      Dec (radians)
+*     DR5       d      proper motion in RA (dRA/dt, rad/Jyear)
+*     DD5       d      proper motion in Dec (dDec/dt, rad/Jyear)
+*
+*  Called:  sla_DS2C6, sla_DAV2M, sla_DMXV, sla_DIMXV, sla_DVXV,
+*           sla_DC62S, sla_DRANRM
+*
+*  Notes:
+*
+*  1)  The proper motions in RA are dRA/dt rather than
+*      cos(Dec)*dRA/dt, and are per year rather than per century.
+*
+*  2)  The FK5 to Hipparcos transformation consists of a pure
+*      rotation and spin;  zonal errors in the FK5 catalogue are
+*      not taken into account.
+*
+*  3)  The published orientation and spin components are interpreted
+*      as "axial vectors".  An axial vector points at the pole of the
+*      rotation and its length is the amount of rotation in radians.
+*
+*  4)  See also sla_FK52H, sla_FK5HZ, sla_HFK5Z.
+*
+*  Reference:
+*
+*     M.Feissel & F.Mignard, Astron. Astrophys. 331, L33-L36 (1998).
+*
+*  P.T.Wallace   Starlink   22 June 1999
+*
+*  Copyright (C) 1999 Rutherford Appleton Laboratory
+*
+*  License:
+*    This program is free software; you can redistribute it and/or modify
+*    it under the terms of the GNU General Public License as published by
+*    the Free Software Foundation; either version 2 of the License, or
+*    (at your option) any later version.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU General Public License for more details.
+*
+*    You should have received a copy of the GNU General Public License
+*    along with this program (see SLA_CONDITIONS); if not, write to the 
+*    Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
+*    Boston, MA  02111-1307  USA
+*
+*-
+
+      IMPLICIT NONE
+
+      DOUBLE PRECISION RH,DH,DRH,DDH,R5,D5,DR5,DD5
+
+      DOUBLE PRECISION AS2R
+      PARAMETER (AS2R=0.484813681109535994D-5)
+
+*  FK5 to Hipparcos orientation and spin (radians, radians/year)
+      DOUBLE PRECISION EPX,EPY,EPZ
+      DOUBLE PRECISION OMX,OMY,OMZ
+
+      PARAMETER ( EPX = -19.9D-3 * AS2R,
+     :            EPY =  -9.1D-3 * AS2R,
+     :            EPZ = +22.9D-3 * AS2R )
+
+      PARAMETER ( OMX = -0.30D-3 * AS2R,
+     :            OMY = +0.60D-3 * AS2R,
+     :            OMZ = +0.70D-3 * AS2R )
+
+      DOUBLE PRECISION PVH(6),ORTN(3),R5H(3,3),S5(3),SH(3),VV(3),
+     :                 PV5(6),W,R,V
+      INTEGER I
+
+      DOUBLE PRECISION sla_DRANRM
+
+
+
+*  Hipparcos barycentric position/velocity 6-vector (normalized).
+      CALL sla_DS2C6(RH,DH,1D0,DRH,DDH,0D0,PVH)
+
+*  FK5 to Hipparcos orientation matrix.
+      ORTN(1) = EPX
+      ORTN(2) = EPY
+      ORTN(3) = EPZ
+      CALL sla_DAV2M(ORTN,R5H)
+
+*  Hipparcos wrt FK5 spin vector.
+      S5(1) = OMX
+      S5(2) = OMY
+      S5(3) = OMZ
+
+*  Rotate the spin vector into the Hipparcos frame.
+      CALL sla_DMXV(R5H,S5,SH)
+
+*  De-orient & de-spin the 6-vector into FK5 J2000.
+      CALL sla_DIMXV(R5H,PVH,PV5)
+      CALL sla_DVXV(PVH,SH,VV)
+      DO I=1,3
+         VV(I) = PVH(I+3)-VV(I)
+      END DO
+      CALL sla_DIMXV(R5H,VV,PV5(4))
+
+*  FK5 6-vector to spherical.
+      CALL sla_DC62S(PV5,W,D5,R,DR5,DD5,V)
+      R5 = sla_DRANRM(W)
+
+      END