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slalib/map.f

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+      SUBROUTINE sla_MAP (RM, DM, PR, PD, PX, RV, EQ, DATE, RA, DA)
+*+
+*     - - - -
+*      M A P
+*     - - - -
+*
+*  Transform star RA,Dec from mean place to geocentric apparent
+*
+*  The reference frames and timescales used are post IAU 1976.
+*
+*  References:
+*     1984 Astronomical Almanac, pp B39-B41.
+*     (also Lederle & Schwan, Astron. Astrophys. 134,
+*      1-6, 1984)
+*
+*  Given:
+*     RM,DM    dp     mean RA,Dec (rad)
+*     PR,PD    dp     proper motions:  RA,Dec changes per Julian year
+*     PX       dp     parallax (arcsec)
+*     RV       dp     radial velocity (km/sec, +ve if receding)
+*     EQ       dp     epoch and equinox of star data (Julian)
+*     DATE     dp     TDB for apparent place (JD-2400000.5)
+*
+*  Returned:
+*     RA,DA    dp     apparent RA,Dec (rad)
+*
+*  Called:
+*     sla_MAPPA       star-independent parameters
+*     sla_MAPQK       quick mean to apparent
+*
+*  Notes:
+*
+*  1)  EQ is the Julian epoch specifying both the reference frame and
+*      the epoch of the position - usually 2000.  For positions where
+*      the epoch and equinox are different, use the routine sla_PM to
+*      apply proper motion corrections before using this routine.
+*
+*  2)  The distinction between the required TDB and TT is always
+*      negligible.  Moreover, for all but the most critical
+*      applications UTC is adequate.
+*
+*  3)  The proper motions in RA are dRA/dt rather than cos(Dec)*dRA/dt.
+*
+*  4)  This routine may be wasteful for some applications because it
+*      recomputes the Earth position/velocity and the precession-
+*      nutation matrix each time, and because it allows for parallax
+*      and proper motion.  Where multiple transformations are to be
+*      carried out for one epoch, a faster method is to call the
+*      sla_MAPPA routine once and then either the sla_MAPQK routine
+*      (which includes parallax and proper motion) or sla_MAPQKZ (which
+*      assumes zero parallax and proper motion).
+*
+*  5)  The accuracy is sub-milliarcsecond, limited by the
+*      precession-nutation model (IAU 1976 precession, Shirai &
+*      Fukushima 2001 forced nutation and precession corrections).
+*
+*  6)  The accuracy is further limited by the routine sla_EVP, called
+*      by sla_MAPPA, which computes the Earth position and velocity
+*      using the methods of Stumpff.  The maximum error is about
+*      0.3 mas.
+*
+*  P.T.Wallace   Starlink   17 September 2001
+*
+*  Copyright (C) 2001 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 RM,DM,PR,PD,PX,RV,EQ,DATE,RA,DA
+
+      DOUBLE PRECISION AMPRMS(21)
+
+
+
+*  Star-independent parameters
+      CALL sla_MAPPA(EQ,DATE,AMPRMS)
+
+*  Mean to apparent
+      CALL sla_MAPQK(RM,DM,PR,PD,PX,RV,AMPRMS,RA,DA)
+
+      END