| 1 | #include "sofa.h"
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| 2 |
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| 3 | void iauAticqn(double ri, double di, iauASTROM *astrom,
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| 4 | int n, iauLDBODY b[], double *rc, double *dc)
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| 5 | /*
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| 6 | ** - - - - - - - - -
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| 7 | ** i a u A t i c q n
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| 8 | ** - - - - - - - - -
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| 9 | **
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| 10 | ** Quick CIRS to ICRS astrometric place transformation, given the star-
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| 11 | ** independent astrometry parameters plus a list of light-deflecting
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| 12 | ** bodies.
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| 13 | **
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| 14 | ** Use of this function is appropriate when efficiency is important and
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| 15 | ** where many star positions are all to be transformed for one date.
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| 16 | ** The star-independent astrometry parameters can be obtained by
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| 17 | ** calling one of the functions iauApci[13], iauApcg[13], iauApco[13]
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| 18 | ** or iauApcs[13].
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| 19 | *
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| 20 | * If the only light-deflecting body to be taken into account is the
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| 21 | * Sun, the iauAticq function can be used instead.
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| 22 | **
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| 23 | ** This function is part of the International Astronomical Union's
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| 24 | ** SOFA (Standards of Fundamental Astronomy) software collection.
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| 25 | **
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| 26 | ** Status: support function.
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| 27 | **
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| 28 | ** Given:
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| 29 | ** ri,di double CIRS RA,Dec (radians)
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| 30 | ** astrom iauASTROM* star-independent astrometry parameters:
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| 31 | ** pmt double PM time interval (SSB, Julian years)
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| 32 | ** eb double[3] SSB to observer (vector, au)
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| 33 | ** eh double[3] Sun to observer (unit vector)
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| 34 | ** em double distance from Sun to observer (au)
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| 35 | ** v double[3] barycentric observer velocity (vector, c)
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| 36 | ** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
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| 37 | ** bpn double[3][3] bias-precession-nutation matrix
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| 38 | ** along double longitude + s' (radians)
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| 39 | ** xpl double polar motion xp wrt local meridian (radians)
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| 40 | ** ypl double polar motion yp wrt local meridian (radians)
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| 41 | ** sphi double sine of geodetic latitude
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| 42 | ** cphi double cosine of geodetic latitude
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| 43 | ** diurab double magnitude of diurnal aberration vector
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| 44 | ** eral double "local" Earth rotation angle (radians)
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| 45 | ** refa double refraction constant A (radians)
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| 46 | ** refb double refraction constant B (radians)
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| 47 | ** n int number of bodies (Note 3)
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| 48 | ** b iauLDBODY[n] data for each of the n bodies (Notes 3,4):
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| 49 | ** bm double mass of the body (solar masses, Note 5)
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| 50 | ** dl double deflection limiter (Note 6)
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| 51 | ** pv [2][3] barycentric PV of the body (au, au/day)
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| 52 | **
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| 53 | ** Returned:
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| 54 | ** rc,dc double ICRS astrometric RA,Dec (radians)
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| 55 | **
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| 56 | ** Notes:
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| 57 | **
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| 58 | ** 1) Iterative techniques are used for the aberration and light
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| 59 | ** deflection corrections so that the functions iauAticqn and
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| 60 | ** iauAtciqn are accurate inverses; even at the edge of the Sun's
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| 61 | ** disk the discrepancy is only about 1 nanoarcsecond.
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| 62 | **
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| 63 | ** 2) If the only light-deflecting body to be taken into account is the
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| 64 | ** Sun, the iauAticq function can be used instead.
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| 65 | **
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| 66 | ** 3) The struct b contains n entries, one for each body to be
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| 67 | ** considered. If n = 0, no gravitational light deflection will be
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| 68 | ** applied, not even for the Sun.
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| 69 | **
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| 70 | ** 4) The struct b should include an entry for the Sun as well as for
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| 71 | ** any planet or other body to be taken into account. The entries
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| 72 | ** should be in the order in which the light passes the body.
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| 73 | **
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| 74 | ** 5) In the entry in the b struct for body i, the mass parameter
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| 75 | ** b[i].bm can, as required, be adjusted in order to allow for such
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| 76 | ** effects as quadrupole field.
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| 77 | **
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| 78 | ** 6) The deflection limiter parameter b[i].dl is phi^2/2, where phi is
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| 79 | ** the angular separation (in radians) between star and body at
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| 80 | ** which limiting is applied. As phi shrinks below the chosen
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| 81 | ** threshold, the deflection is artificially reduced, reaching zero
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| 82 | ** for phi = 0. Example values suitable for a terrestrial
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| 83 | ** observer, together with masses, are as follows:
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| 84 | **
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| 85 | ** body i b[i].bm b[i].dl
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| 86 | **
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| 87 | ** Sun 1.0 6e-6
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| 88 | ** Jupiter 0.00095435 3e-9
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| 89 | ** Saturn 0.00028574 3e-10
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| 90 | **
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| 91 | ** 7) For efficiency, validation of the contents of the b array is
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| 92 | ** omitted. The supplied masses must be greater than zero, the
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| 93 | ** position and velocity vectors must be right, and the deflection
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| 94 | ** limiter greater than zero.
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| 95 | **
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| 96 | ** Called:
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| 97 | ** iauS2c spherical coordinates to unit vector
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| 98 | ** iauTrxp product of transpose of r-matrix and p-vector
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| 99 | ** iauZp zero p-vector
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| 100 | ** iauAb stellar aberration
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| 101 | ** iauLdn light deflection by n bodies
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| 102 | ** iauC2s p-vector to spherical
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| 103 | ** iauAnp normalize angle into range +/- pi
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| 104 | **
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| 105 | ** This revision: 2013 October 9
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| 106 | **
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| 107 | ** SOFA release 2015-02-09
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| 108 | **
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| 109 | ** Copyright (C) 2015 IAU SOFA Board. See notes at end.
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| 110 | */
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| 111 | {
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| 112 | int j, i;
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| 113 | double pi[3], ppr[3], pnat[3], pco[3], w, d[3], before[3], r2, r,
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| 114 | after[3];
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| 115 |
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| 116 | /* CIRS RA,Dec to Cartesian. */
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| 117 | iauS2c(ri, di, pi);
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| 118 |
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| 119 | /* Bias-precession-nutation, giving GCRS proper direction. */
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| 120 | iauTrxp(astrom->bpn, pi, ppr);
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| 121 |
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| 122 | /* Aberration, giving GCRS natural direction. */
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| 123 | iauZp(d);
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| 124 | for (j = 0; j < 2; j++) {
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| 125 | r2 = 0.0;
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| 126 | for (i = 0; i < 3; i++) {
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| 127 | w = ppr[i] - d[i];
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| 128 | before[i] = w;
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| 129 | r2 += w*w;
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| 130 | }
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| 131 | r = sqrt(r2);
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| 132 | for (i = 0; i < 3; i++) {
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| 133 | before[i] /= r;
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| 134 | }
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| 135 | iauAb(before, astrom->v, astrom->em, astrom->bm1, after);
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| 136 | r2 = 0.0;
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| 137 | for (i = 0; i < 3; i++) {
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| 138 | d[i] = after[i] - before[i];
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| 139 | w = ppr[i] - d[i];
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| 140 | pnat[i] = w;
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| 141 | r2 += w*w;
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| 142 | }
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| 143 | r = sqrt(r2);
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| 144 | for (i = 0; i < 3; i++) {
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| 145 | pnat[i] /= r;
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| 146 | }
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| 147 | }
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| 148 |
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| 149 | /* Light deflection, giving BCRS coordinate direction. */
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| 150 | iauZp(d);
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| 151 | for (j = 0; j < 5; j++) {
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| 152 | r2 = 0.0;
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| 153 | for (i = 0; i < 3; i++) {
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| 154 | w = pnat[i] - d[i];
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| 155 | before[i] = w;
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| 156 | r2 += w*w;
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| 157 | }
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| 158 | r = sqrt(r2);
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| 159 | for (i = 0; i < 3; i++) {
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| 160 | before[i] /= r;
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| 161 | }
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| 162 | iauLdn(n, b, astrom->eb, before, after);
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| 163 | r2 = 0.0;
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| 164 | for (i = 0; i < 3; i++) {
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| 165 | d[i] = after[i] - before[i];
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| 166 | w = pnat[i] - d[i];
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| 167 | pco[i] = w;
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| 168 | r2 += w*w;
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| 169 | }
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| 170 | r = sqrt(r2);
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| 171 | for (i = 0; i < 3; i++) {
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| 172 | pco[i] /= r;
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| 173 | }
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| 174 | }
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| 175 |
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| 176 | /* ICRS astrometric RA,Dec. */
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| 177 | iauC2s(pco, &w, dc);
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| 178 | *rc = iauAnp(w);
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| 179 |
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| 180 | /* Finished. */
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| 181 |
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| 182 | /*----------------------------------------------------------------------
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| 183 | **
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| 184 | ** Copyright (C) 2015
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| 185 | ** Standards Of Fundamental Astronomy Board
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| 186 | ** of the International Astronomical Union.
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| 187 | **
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| 188 | ** =====================
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| 189 | ** SOFA Software License
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| 190 | ** =====================
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| 191 | **
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| 192 | ** NOTICE TO USER:
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| 193 | **
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| 194 | ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
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| 195 | ** CONDITIONS WHICH APPLY TO ITS USE.
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| 196 | **
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| 197 | ** 1. The Software is owned by the IAU SOFA Board ("SOFA").
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| 198 | **
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| 199 | ** 2. Permission is granted to anyone to use the SOFA software for any
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| 200 | ** purpose, including commercial applications, free of charge and
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| 201 | ** without payment of royalties, subject to the conditions and
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| 202 | ** restrictions listed below.
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| 203 | **
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| 204 | ** 3. You (the user) may copy and distribute SOFA source code to others,
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| 205 | ** and use and adapt its code and algorithms in your own software,
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| 206 | ** on a world-wide, royalty-free basis. That portion of your
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| 207 | ** distribution that does not consist of intact and unchanged copies
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| 208 | ** of SOFA source code files is a "derived work" that must comply
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| 209 | ** with the following requirements:
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| 210 | **
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| 211 | ** a) Your work shall be marked or carry a statement that it
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| 212 | ** (i) uses routines and computations derived by you from
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| 213 | ** software provided by SOFA under license to you; and
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| 214 | ** (ii) does not itself constitute software provided by and/or
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| 215 | ** endorsed by SOFA.
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| 216 | **
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| 217 | ** b) The source code of your derived work must contain descriptions
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| 218 | ** of how the derived work is based upon, contains and/or differs
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| 219 | ** from the original SOFA software.
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| 220 | **
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| 221 | ** c) The names of all routines in your derived work shall not
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| 222 | ** include the prefix "iau" or "sofa" or trivial modifications
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| 223 | ** thereof such as changes of case.
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| 224 | **
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| 225 | ** d) The origin of the SOFA components of your derived work must
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| 226 | ** not be misrepresented; you must not claim that you wrote the
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| 227 | ** original software, nor file a patent application for SOFA
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| 228 | ** software or algorithms embedded in the SOFA software.
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| 229 | **
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| 230 | ** e) These requirements must be reproduced intact in any source
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| 231 | ** distribution and shall apply to anyone to whom you have
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| 232 | ** granted a further right to modify the source code of your
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| 233 | ** derived work.
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| 234 | **
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| 235 | ** Note that, as originally distributed, the SOFA software is
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| 236 | ** intended to be a definitive implementation of the IAU standards,
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| 237 | ** and consequently third-party modifications are discouraged. All
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| 238 | ** variations, no matter how minor, must be explicitly marked as
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| 239 | ** such, as explained above.
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| 240 | **
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| 241 | ** 4. You shall not cause the SOFA software to be brought into
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| 242 | ** disrepute, either by misuse, or use for inappropriate tasks, or
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| 243 | ** by inappropriate modification.
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| 244 | **
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| 245 | ** 5. The SOFA software is provided "as is" and SOFA makes no warranty
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| 246 | ** as to its use or performance. SOFA does not and cannot warrant
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| 247 | ** the performance or results which the user may obtain by using the
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| 248 | ** SOFA software. SOFA makes no warranties, express or implied, as
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| 249 | ** to non-infringement of third party rights, merchantability, or
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| 250 | ** fitness for any particular purpose. In no event will SOFA be
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| 251 | ** liable to the user for any consequential, incidental, or special
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| 252 | ** damages, including any lost profits or lost savings, even if a
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| 253 | ** SOFA representative has been advised of such damages, or for any
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| 254 | ** claim by any third party.
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| 255 | **
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| 256 | ** 6. The provision of any version of the SOFA software under the terms
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| 257 | ** and conditions specified herein does not imply that future
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| 258 | ** versions will also be made available under the same terms and
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| 259 | ** conditions.
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| 260 | *
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| 261 | ** In any published work or commercial product which uses the SOFA
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| 262 | ** software directly, acknowledgement (see www.iausofa.org) is
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| 263 | ** appreciated.
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| 264 | **
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| 265 | ** Correspondence concerning SOFA software should be addressed as
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| 266 | ** follows:
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| 267 | **
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| 268 | ** By email: sofa@ukho.gov.uk
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| 269 | ** By post: IAU SOFA Center
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| 270 | ** HM Nautical Almanac Office
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| 271 | ** UK Hydrographic Office
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| 272 | ** Admiralty Way, Taunton
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| 273 | ** Somerset, TA1 2DN
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| 274 | ** United Kingdom
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| 275 | **
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| 276 | **--------------------------------------------------------------------*/
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| 277 |
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| 278 | }
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