mirror of
https://github.com/eddyem/BTA_lib.git
synced 2025-12-06 10:45:11 +03:00
125 lines
3.7 KiB
Fortran
125 lines
3.7 KiB
Fortran
SUBROUTINE sla_FK5HZ (R5,D5,EPOCH,RH,DH)
|
|
*+
|
|
* - - - - - -
|
|
* F K 5 H Z
|
|
* - - - - - -
|
|
*
|
|
* Transform an FK5 (J2000) star position into the frame of the
|
|
* Hipparcos catalogue, assuming zero Hipparcos proper motion.
|
|
*
|
|
* (double precision)
|
|
*
|
|
* This routine converts a star position from the FK5 system to
|
|
* the Hipparcos system, in such a way that the Hipparcos proper
|
|
* motion is zero. Because such a star has, in general, a non-zero
|
|
* proper motion in the FK5 system, the routine requires the epoch
|
|
* at which the position in the FK5 system was determined.
|
|
*
|
|
* Given:
|
|
* R5 d FK5 RA (radians), equinox J2000, epoch EPOCH
|
|
* D5 d FK5 Dec (radians), equinox J2000, epoch EPOCH
|
|
* EPOCH d Julian epoch (TDB)
|
|
*
|
|
* Returned (all Hipparcos):
|
|
* RH d RA (radians)
|
|
* DH d Dec (radians)
|
|
*
|
|
* Called: sla_DCS2C, sla_DAV2M, sla_DIMXV, sla_DMXV, sla_DCC2S,
|
|
* sla_DRANRM
|
|
*
|
|
* Notes:
|
|
*
|
|
* 1) The FK5 to Hipparcos transformation consists of a pure
|
|
* rotation and spin; zonal errors in the FK5 catalogue are
|
|
* not taken into account.
|
|
*
|
|
* 2) 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.
|
|
*
|
|
* 3) See also sla_FK52H, sla_H2FK5, 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 R5,D5,EPOCH,RH,DH
|
|
|
|
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 P5E(3),ORTN(3),R5H(3,3),T,VST(3),RST(3,3),
|
|
: P5(3),PH(3),W
|
|
|
|
DOUBLE PRECISION sla_DRANRM
|
|
|
|
|
|
|
|
* FK5 barycentric position vector.
|
|
CALL sla_DCS2C(R5,D5,P5E)
|
|
|
|
* FK5 to Hipparcos orientation matrix.
|
|
ORTN(1) = EPX
|
|
ORTN(2) = EPY
|
|
ORTN(3) = EPZ
|
|
CALL sla_DAV2M(ORTN,R5H)
|
|
|
|
* Time interval from epoch to J2000.
|
|
T = 2000D0-EPOCH
|
|
|
|
* Axial vector: accumulated Hipparcos wrt FK5 spin over that interval.
|
|
VST(1) = OMX*T
|
|
VST(2) = OMY*T
|
|
VST(3) = OMZ*T
|
|
|
|
* Express the accumulated spin as a rotation matrix.
|
|
CALL sla_DAV2M(VST,RST)
|
|
|
|
* Derotate the vector's FK5 axes back to epoch.
|
|
CALL sla_DIMXV(RST,P5E,P5)
|
|
|
|
* Rotate the vector into the Hipparcos frame.
|
|
CALL sla_DMXV(R5H,P5,PH)
|
|
|
|
* Hipparcos vector to spherical.
|
|
CALL sla_DCC2S(PH,W,DH)
|
|
RH = sla_DRANRM(W)
|
|
|
|
END
|