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