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99 lines
3.4 KiB
Fortran
99 lines
3.4 KiB
Fortran
SUBROUTINE sla_MAP (RM, DM, PR, PD, PX, RV, EQ, DATE, RA, DA)
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*+
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* - - - -
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* M A P
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* - - - -
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*
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* Transform star RA,Dec from mean place to geocentric apparent
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*
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* The reference frames and timescales used are post IAU 1976.
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*
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* References:
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* 1984 Astronomical Almanac, pp B39-B41.
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* (also Lederle & Schwan, Astron. Astrophys. 134,
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* 1-6, 1984)
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*
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* Given:
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* RM,DM dp mean RA,Dec (rad)
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* PR,PD dp proper motions: RA,Dec changes per Julian year
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* PX dp parallax (arcsec)
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* RV dp radial velocity (km/sec, +ve if receding)
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* EQ dp epoch and equinox of star data (Julian)
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* DATE dp TDB for apparent place (JD-2400000.5)
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*
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* Returned:
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* RA,DA dp apparent RA,Dec (rad)
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*
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* Called:
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* sla_MAPPA star-independent parameters
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* sla_MAPQK quick mean to apparent
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*
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* Notes:
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*
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* 1) EQ is the Julian epoch specifying both the reference frame and
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* the epoch of the position - usually 2000. For positions where
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* the epoch and equinox are different, use the routine sla_PM to
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* apply proper motion corrections before using this routine.
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*
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* 2) The distinction between the required TDB and TT is always
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* negligible. Moreover, for all but the most critical
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* applications UTC is adequate.
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*
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* 3) The proper motions in RA are dRA/dt rather than cos(Dec)*dRA/dt.
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*
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* 4) This routine may be wasteful for some applications because it
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* recomputes the Earth position/velocity and the precession-
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* nutation matrix each time, and because it allows for parallax
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* and proper motion. Where multiple transformations are to be
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* carried out for one epoch, a faster method is to call the
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* sla_MAPPA routine once and then either the sla_MAPQK routine
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* (which includes parallax and proper motion) or sla_MAPQKZ (which
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* assumes zero parallax and proper motion).
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*
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* 5) The accuracy is sub-milliarcsecond, limited by the
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* precession-nutation model (IAU 1976 precession, Shirai &
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* Fukushima 2001 forced nutation and precession corrections).
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*
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* 6) The accuracy is further limited by the routine sla_EVP, called
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* by sla_MAPPA, which computes the Earth position and velocity
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* using the methods of Stumpff. The maximum error is about
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* 0.3 mas.
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*
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* P.T.Wallace Starlink 17 September 2001
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*
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* Copyright (C) 2001 Rutherford Appleton Laboratory
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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DOUBLE PRECISION RM,DM,PR,PD,PX,RV,EQ,DATE,RA,DA
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DOUBLE PRECISION AMPRMS(21)
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* Star-independent parameters
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CALL sla_MAPPA(EQ,DATE,AMPRMS)
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* Mean to apparent
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CALL sla_MAPQK(RM,DM,PR,PD,PX,RV,AMPRMS,RA,DA)
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END
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