SUBROUTINE sla_MAPQKZ (RM, DM, AMPRMS, RA, DA) *+ * - - - - - - - * M A P Q K Z * - - - - - - - * * Quick mean to apparent place: transform a star RA,Dec from * mean place to geocentric apparent place, given the * star-independent parameters, and assuming zero parallax * and proper motion. * * Use of this routine is appropriate when efficiency is important * and where many star positions, all with parallax and proper * motion either zero or already allowed for, and all referred to * the same equator and equinox, are to be transformed for one * epoch. The star-independent parameters can be obtained by * calling the sla_MAPPA routine. * * The corresponding routine for the case of non-zero parallax * and proper motion is sla_MAPQK. * * The reference frames and timescales used are post IAU 1976. * * Given: * RM,DM d mean RA,Dec (rad) * AMPRMS d(21) star-independent mean-to-apparent parameters: * * (1-4) not used * (5-7) heliocentric direction of the Earth (unit vector) * (8) (grav rad Sun)*2/(Sun-Earth distance) * (9-11) ABV: barycentric Earth velocity in units of c * (12) sqrt(1-v**2) where v=modulus(ABV) * (13-21) precession/nutation (3,3) matrix * * Returned: * RA,DA d apparent RA,Dec (rad) * * References: * 1984 Astronomical Almanac, pp B39-B41. * (also Lederle & Schwan, Astron. Astrophys. 134, * 1-6, 1984) * * Notes: * * 1) The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to the * mean equinox and equator of epoch EQ. * * 2) Strictly speaking, the routine is not valid for solar-system * sources, though the error will usually be extremely small. * However, to prevent gross errors in the case where the * position of the Sun is specified, the gravitational * deflection term is restrained within about 920 arcsec of the * centre of the Sun's disc. The term has a maximum value of * about 1.85 arcsec at this radius, and decreases to zero as * the centre of the disc is approached. * * Called: sla_DCS2C, sla_DVDV, sla_DMXV, sla_DCC2S, sla_DRANRM * * P.T.Wallace Starlink 18 March 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 RM,DM,AMPRMS(21),RA,DA INTEGER I DOUBLE PRECISION GR2E,AB1,EHN(3),ABV(3), : P(3),PDE,PDEP1,W,P1(3),P1DV, : P1DVP1,P2(3),P3(3) DOUBLE PRECISION sla_DVDV,sla_DRANRM * Unpack scalar and vector parameters GR2E = AMPRMS(8) AB1 = AMPRMS(12) DO I=1,3 EHN(I) = AMPRMS(I+4) ABV(I) = AMPRMS(I+8) END DO * Spherical to x,y,z CALL sla_DCS2C(RM,DM,P) * Light deflection PDE = sla_DVDV(P,EHN) PDEP1 = PDE+1D0 W = GR2E/MAX(PDEP1,1D-5) DO I=1,3 P1(I) = P(I)+W*(EHN(I)-PDE*P(I)) END DO * Aberration P1DV = sla_DVDV(P1,ABV) P1DVP1 = P1DV+1D0 W = 1D0+P1DV/(AB1+1D0) DO I=1,3 P2(I) = (AB1*P1(I)+W*ABV(I))/P1DVP1 END DO * Precession and nutation CALL sla_DMXV(AMPRMS(13),P2,P3) * Geocentric apparent RA,Dec CALL sla_DCC2S(P3,RA,DA) RA = sla_DRANRM(RA) END