mirror of
https://github.com/eddyem/apogee_control.git
synced 2025-12-06 18:55:11 +03:00
102 lines
2.9 KiB
Fortran
102 lines
2.9 KiB
Fortran
SUBROUTINE sla_PRECES (SYSTEM, EP0, EP1, RA, DC)
|
|
*+
|
|
* - - - - - - -
|
|
* P R E C E S
|
|
* - - - - - - -
|
|
*
|
|
* Precession - either FK4 (Bessel-Newcomb, pre IAU 1976) or
|
|
* FK5 (Fricke, post IAU 1976) as required.
|
|
*
|
|
* Given:
|
|
* SYSTEM char precession to be applied: 'FK4' or 'FK5'
|
|
* EP0,EP1 dp starting and ending epoch
|
|
* RA,DC dp RA,Dec, mean equator & equinox of epoch EP0
|
|
*
|
|
* Returned:
|
|
* RA,DC dp RA,Dec, mean equator & equinox of epoch EP1
|
|
*
|
|
* Called: sla_DRANRM, sla_PREBN, sla_PREC, sla_DCS2C,
|
|
* sla_DMXV, sla_DCC2S
|
|
*
|
|
* Notes:
|
|
*
|
|
* 1) Lowercase characters in SYSTEM are acceptable.
|
|
*
|
|
* 2) The epochs are Besselian if SYSTEM='FK4' and Julian if 'FK5'.
|
|
* For example, to precess coordinates in the old system from
|
|
* equinox 1900.0 to 1950.0 the call would be:
|
|
* CALL sla_PRECES ('FK4', 1900D0, 1950D0, RA, DC)
|
|
*
|
|
* 3) This routine will NOT correctly convert between the old and
|
|
* the new systems - for example conversion from B1950 to J2000.
|
|
* For these purposes see sla_FK425, sla_FK524, sla_FK45Z and
|
|
* sla_FK54Z.
|
|
*
|
|
* 4) If an invalid SYSTEM is supplied, values of -99D0,-99D0 will
|
|
* be returned for both RA and DC.
|
|
*
|
|
* P.T.Wallace Starlink 20 April 1990
|
|
*
|
|
* Copyright (C) 1995 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
|
|
|
|
CHARACTER SYSTEM*(*)
|
|
DOUBLE PRECISION EP0,EP1,RA,DC
|
|
|
|
DOUBLE PRECISION PM(3,3),V1(3),V2(3)
|
|
CHARACTER SYSUC*3
|
|
|
|
DOUBLE PRECISION sla_DRANRM
|
|
|
|
|
|
|
|
|
|
* Convert to uppercase and validate SYSTEM
|
|
SYSUC=SYSTEM
|
|
IF (SYSUC(1:1).EQ.'f') SYSUC(1:1)='F'
|
|
IF (SYSUC(2:2).EQ.'k') SYSUC(2:2)='K'
|
|
IF (SYSUC.NE.'FK4'.AND.SYSUC.NE.'FK5') THEN
|
|
RA=-99D0
|
|
DC=-99D0
|
|
ELSE
|
|
|
|
* Generate appropriate precession matrix
|
|
IF (SYSUC.EQ.'FK4') THEN
|
|
CALL sla_PREBN(EP0,EP1,PM)
|
|
ELSE
|
|
CALL sla_PREC(EP0,EP1,PM)
|
|
END IF
|
|
|
|
* Convert RA,Dec to x,y,z
|
|
CALL sla_DCS2C(RA,DC,V1)
|
|
|
|
* Precess
|
|
CALL sla_DMXV(PM,V1,V2)
|
|
|
|
* Back to RA,Dec
|
|
CALL sla_DCC2S(V2,RA,DC)
|
|
RA=sla_DRANRM(RA)
|
|
|
|
END IF
|
|
|
|
END
|