/* *+ * Name: * palAmpqk * Purpose: * Convert star RA,Dec from geocentric apparent to mean place. * Language: * Starlink ANSI C * Type of Module: * Library routine * Invocation: * void palAmpqk ( double ra, double da, double amprms[21], * double *rm, double *dm ) * Arguments: * ra = double (Given) * Apparent RA (radians). * da = double (Given) * Apparent Dec (radians). * amprms = double[21] (Given) * Star-independent mean-to-apparent parameters (see palMappa): * (0) time interval for proper motion (Julian years) * (1-3) barycentric position of the Earth (AU) * (4-6) not used * (7) not used * (8-10) abv: barycentric Earth velocity in units of c * (11) sqrt(1-v*v) where v=modulus(abv) * (12-20) precession/nutation (3,3) matrix * rm = double (Returned) * Mean RA (radians). * dm = double (Returned) * Mean Dec (radians). * Description: * Convert star RA,Dec from geocentric apparent to mean place. The "mean" * coordinate system is in fact close to ICRS. Use of this function * is appropriate when efficiency is important and where many star * positions are all to be transformed for one epoch and equinox. The * star-independent parameters can be obtained by calling the palMappa * function. * Authors: * PTW: Pat Wallace (STFC) * {enter_new_authors_here} * History: * 2012-02-13 (PTW): * Initial version. * Adapted with permission from the Fortran SLALIB library. * {enter_further_changes_here} * Copyright: * Copyright (C) 2000 Rutherford Appleton Laboratory * Copyright (C) 2012 Science and Technology Facilities Council. * All Rights Reserved. * Licence: * This program is free software: you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation, either * version 3 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General * License along with this program. If not, see * . * Bugs: * {note_any_bugs_here} *- */ #include "pal.h" #include "pal1sofa.h" void palAmpqk ( double ra, double da, double amprms[21], double *rm, double *dm ){ /* Local Variables: */ double ab1; /* sqrt(1-v*v) where v=modulus of Earth vel */ double abv[3]; /* Earth velocity wrt SSB (c, FK5) */ double p1[3], p2[3], p3[3]; /* work vectors */ double ab1p1, p1dv, p1dvp1, w; int i, j; /* Unpack some of the parameters */ ab1 = amprms[11]; for( i = 0; i < 3; i++ ) { abv[i] = amprms[i + 8]; } /* Apparent RA,Dec to Cartesian */ eraS2c( ra, da, p3 ); /* Precession and nutation */ eraTrxp( (double(*)[3]) &rms[12], p3, p2 ); /* Aberration */ ab1p1 = ab1 + 1.0; for( i = 0; i < 3; i++ ) { p1[i] = p2[i]; } for( j = 0; j < 2; j++ ) { p1dv = eraPdp( p1, abv ); p1dvp1 = 1.0 + p1dv; w = 1.0 + p1dv / ab1p1; for( i = 0; i < 3; i++ ) { p1[i] = ( p1dvp1 * p2[i] - w * abv[i] ) / ab1; } eraPn( p1, &w, p3 ); for( i = 0; i < 3; i++ ) { p1[i] = p3[i]; } } /* Mean RA,Dec */ eraC2s( p1, rm, dm ); *rm = eraAnp( *rm ); }