| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palMapqkz
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| 5 |
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| 6 | * Purpose:
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| 7 | * Quick mean to apparent place (no proper motion or parallax).
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| 8 |
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| 9 | * Language:
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| 10 | * Starlink ANSI C
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| 11 |
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| 12 | * Type of Module:
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| 13 | * Library routine
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| 14 |
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| 15 | * Invocation:
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| 16 | * void palMapqkz( double rm, double dm, double amprms[21],
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| 17 | * double *ra, double *da )
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| 18 |
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| 19 | * Arguments:
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| 20 | * rm = double (Given)
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| 21 | * Mean RA (radians).
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| 22 | * dm = double (Given)
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| 23 | * Mean Dec (radians).
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| 24 | * amprms = double[21] (Given)
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| 25 | * Star-independent mean-to-apparent parameters (see palMappa):
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| 26 | * (0-3) not used
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| 27 | * (4-6) heliocentric direction of the Earth (unit vector)
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| 28 | * (7) not used
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| 29 | * (8-10) abv: barycentric Earth velocity in units of c
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| 30 | * (11) sqrt(1-v^2) where v=modulus(abv)
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| 31 | * (12-20) precession/nutation (3,3) matrix
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| 32 | * ra = double * (Returned)
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| 33 | * Apparent RA (radians).
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| 34 | * da = double * (Returned)
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| 35 | * Apparent Dec (radians).
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| 36 |
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| 37 | * Description:
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| 38 | * Quick mean to apparent place: transform a star RA,dec from
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| 39 | * mean place to geocentric apparent place, given the
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| 40 | * star-independent parameters, and assuming zero parallax
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| 41 | * and proper motion.
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| 42 | *
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| 43 | * Use of this function is appropriate when efficiency is important
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| 44 | * and where many star positions, all with parallax and proper
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| 45 | * motion either zero or already allowed for, and all referred to
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| 46 | * the same equator and equinox, are to be transformed for one
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| 47 | * epoch. The star-independent parameters can be obtained by
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| 48 | * calling the palMappa function.
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| 49 | *
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| 50 | * The corresponding function for the case of non-zero parallax
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| 51 | * and proper motion is palMapqk.
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| 52 |
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| 53 | * Notes:
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| 54 | * - The reference systems and timescales used are IAU 2006.
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| 55 | * - The mean place rm, dm and the vectors amprms[1-3] and amprms[4-6]
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| 56 | * are referred to the mean equinox and equator of the epoch
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| 57 | * specified when generating the precession/nutation matrix
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| 58 | * amprms[12-20]. In the call to palMappa (q.v.) normally used
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| 59 | * to populate amprms, this epoch is the first argument (eq).
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| 60 | * - The vector amprms(4-6) is referred to the mean equinox and
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| 61 | * equator of epoch eq.
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| 62 | * - Strictly speaking, the routine is not valid for solar-system
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| 63 | * sources, though the error will usually be extremely small.
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| 64 | * However, to prevent gross errors in the case where the
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| 65 | * position of the Sun is specified, the gravitational
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| 66 | * deflection term is restrained within about 920 arcsec of the
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| 67 | * centre of the Sun's disc. The term has a maximum value of
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| 68 | * about 1.85 arcsec at this radius, and decreases to zero as
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| 69 | * the centre of the disc is approached.
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| 70 |
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| 71 | * Authors:
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| 72 | * PTW: Pat Wallace (STFC)
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| 73 | * {enter_new_authors_here}
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| 74 |
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| 75 | * History:
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| 76 | * 2012-02-13 (PTW):
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| 77 | * Initial version.
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| 78 | * Adapted with permission from the Fortran SLALIB library.
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| 79 | * {enter_further_changes_here}
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| 80 |
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| 81 | * Copyright:
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| 82 | * Copyright (C) 1999 Rutherford Appleton Laboratory
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| 83 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 84 | * All Rights Reserved.
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| 85 |
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| 86 | * Licence:
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| 87 | * This program is free software: you can redistribute it and/or
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| 88 | * modify it under the terms of the GNU Lesser General Public
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| 89 | * License as published by the Free Software Foundation, either
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| 90 | * version 3 of the License, or (at your option) any later
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| 91 | * version.
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| 92 | *
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| 93 | * This program is distributed in the hope that it will be useful,
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| 94 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 95 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 96 | * GNU Lesser General Public License for more details.
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| 97 | *
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| 98 | * You should have received a copy of the GNU Lesser General
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| 99 | * License along with this program. If not, see
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| 100 | * <http://www.gnu.org/licenses/>.
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| 101 |
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| 102 | * Bugs:
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| 103 | * {note_any_bugs_here}
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| 104 | *-
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| 105 | */
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| 106 |
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| 107 | #include "pal.h"
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| 108 | #include "pal1sofa.h"
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| 109 |
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| 110 | void palMapqkz ( double rm, double dm, double amprms[21], double *ra,
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| 111 | double *da ){
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| 112 |
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| 113 | /* Local Variables: */
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| 114 | int i;
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| 115 | double ab1, abv[3], p[3], w, p1dv, p2[3], p3[3];
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| 116 | double gr2e, pde, pdep1, ehn[3], p1[3];
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| 117 |
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| 118 | /* Unpack scalar and vector parameters. */
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| 119 | ab1 = amprms[11];
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| 120 | gr2e = amprms[7];
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| 121 | for( i = 0; i < 3; i++ ) {
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| 122 | abv[i] = amprms[i+8];
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| 123 | ehn[i] = amprms[i+4];
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| 124 | }
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| 125 |
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| 126 | /* Spherical to x,y,z. */
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| 127 | eraS2c( rm, dm, p );
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| 128 |
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| 129 | /* Light deflection (restrained within the Sun's disc) */
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| 130 | pde = eraPdp( p, ehn );
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| 131 | pdep1 = pde + 1.0;
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| 132 | w = gr2e / ( pdep1 > 1.0e-5 ? pdep1 : 1.0e-5 );
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| 133 | for( i = 0; i < 3; i++) {
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| 134 | p1[i] = p[i] + w * ( ehn[i] - pde * p[i] );
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| 135 | }
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| 136 |
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| 137 | /* Aberration. */
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| 138 | p1dv = eraPdp( p1, abv );
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| 139 | w = 1.0 + p1dv / ( ab1 + 1.0 );
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| 140 | for( i = 0; i < 3; i++ ) {
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| 141 | p2[i] = ( ( ab1 * p1[i] ) + ( w * abv[i] ) );
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| 142 | }
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| 143 |
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| 144 | /* Precession and nutation. */
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| 145 | eraRxp( (double(*)[3]) &rms[12], p2, p3 );
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| 146 |
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| 147 | /* Geocentric apparent RA,dec. */
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| 148 | eraC2s( p3, ra, da );
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| 149 | *ra = eraAnp( *ra );
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| 150 | }
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