#include "erfa.h" void eraAticqn(double ri, double di, eraASTROM *astrom, int n, eraLDBODY b[], double *rc, double *dc) /* ** - - - - - - - - - ** e r a A t i c q n ** - - - - - - - - - ** ** Quick CIRS to ICRS astrometric place transformation, given the star- ** independent astrometry parameters plus a list of light-deflecting ** bodies. ** ** Use of this function is appropriate when efficiency is important and ** where many star positions are all to be transformed for one date. ** The star-independent astrometry parameters can be obtained by ** calling one of the functions eraApci[13], eraApcg[13], eraApco[13] ** or eraApcs[13]. * * If the only light-deflecting body to be taken into account is the * Sun, the eraAticq function can be used instead. ** ** Given: ** ri,di double CIRS RA,Dec (radians) ** astrom eraASTROM* star-independent astrometry parameters: ** pmt double PM time interval (SSB, Julian years) ** eb double[3] SSB to observer (vector, au) ** eh double[3] Sun to observer (unit vector) ** em double distance from Sun to observer (au) ** v double[3] barycentric observer velocity (vector, c) ** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor ** bpn double[3][3] bias-precession-nutation matrix ** along double longitude + s' (radians) ** xpl double polar motion xp wrt local meridian (radians) ** ypl double polar motion yp wrt local meridian (radians) ** sphi double sine of geodetic latitude ** cphi double cosine of geodetic latitude ** diurab double magnitude of diurnal aberration vector ** eral double "local" Earth rotation angle (radians) ** refa double refraction constant A (radians) ** refb double refraction constant B (radians) ** n int number of bodies (Note 3) ** b eraLDBODY[n] data for each of the n bodies (Notes 3,4): ** bm double mass of the body (solar masses, Note 5) ** dl double deflection limiter (Note 6) ** pv [2][3] barycentric PV of the body (au, au/day) ** ** Returned: ** rc,dc double ICRS astrometric RA,Dec (radians) ** ** Notes: ** ** 1) Iterative techniques are used for the aberration and light ** deflection corrections so that the functions eraAticqn and ** eraAtciqn are accurate inverses; even at the edge of the Sun's ** disk the discrepancy is only about 1 nanoarcsecond. ** ** 2) If the only light-deflecting body to be taken into account is the ** Sun, the eraAticq function can be used instead. ** ** 3) The struct b contains n entries, one for each body to be ** considered. If n = 0, no gravitational light deflection will be ** applied, not even for the Sun. ** ** 4) The struct b should include an entry for the Sun as well as for ** any planet or other body to be taken into account. The entries ** should be in the order in which the light passes the body. ** ** 5) In the entry in the b struct for body i, the mass parameter ** b[i].bm can, as required, be adjusted in order to allow for such ** effects as quadrupole field. ** ** 6) The deflection limiter parameter b[i].dl is phi^2/2, where phi is ** the angular separation (in radians) between star and body at ** which limiting is applied. As phi shrinks below the chosen ** threshold, the deflection is artificially reduced, reaching zero ** for phi = 0. Example values suitable for a terrestrial ** observer, together with masses, are as follows: ** ** body i b[i].bm b[i].dl ** ** Sun 1.0 6e-6 ** Jupiter 0.00095435 3e-9 ** Saturn 0.00028574 3e-10 ** ** 7) For efficiency, validation of the contents of the b array is ** omitted. The supplied masses must be greater than zero, the ** position and velocity vectors must be right, and the deflection ** limiter greater than zero. ** ** Called: ** eraS2c spherical coordinates to unit vector ** eraTrxp product of transpose of r-matrix and p-vector ** eraZp zero p-vector ** eraAb stellar aberration ** eraLdn light deflection by n bodies ** eraC2s p-vector to spherical ** eraAnp normalize angle into range +/- pi ** ** Copyright (C) 2013-2017, NumFOCUS Foundation. ** Derived, with permission, from the SOFA library. See notes at end of file. */ { int j, i; double pi[3], ppr[3], pnat[3], pco[3], w, d[3], before[3], r2, r, after[3]; /* CIRS RA,Dec to Cartesian. */ eraS2c(ri, di, pi); /* Bias-precession-nutation, giving GCRS proper direction. */ eraTrxp(astrom->bpn, pi, ppr); /* Aberration, giving GCRS natural direction. */ eraZp(d); for (j = 0; j < 2; j++) { r2 = 0.0; for (i = 0; i < 3; i++) { w = ppr[i] - d[i]; before[i] = w; r2 += w*w; } r = sqrt(r2); for (i = 0; i < 3; i++) { before[i] /= r; } eraAb(before, astrom->v, astrom->em, astrom->bm1, after); r2 = 0.0; for (i = 0; i < 3; i++) { d[i] = after[i] - before[i]; w = ppr[i] - d[i]; pnat[i] = w; r2 += w*w; } r = sqrt(r2); for (i = 0; i < 3; i++) { pnat[i] /= r; } } /* Light deflection, giving BCRS coordinate direction. */ eraZp(d); for (j = 0; j < 5; j++) { r2 = 0.0; for (i = 0; i < 3; i++) { w = pnat[i] - d[i]; before[i] = w; r2 += w*w; } r = sqrt(r2); for (i = 0; i < 3; i++) { before[i] /= r; } eraLdn(n, b, astrom->eb, before, after); r2 = 0.0; for (i = 0; i < 3; i++) { d[i] = after[i] - before[i]; w = pnat[i] - d[i]; pco[i] = w; r2 += w*w; } r = sqrt(r2); for (i = 0; i < 3; i++) { pco[i] /= r; } } /* ICRS astrometric RA,Dec. */ eraC2s(pco, &w, dc); *rc = eraAnp(w); /* Finished. */ } /*---------------------------------------------------------------------- ** ** ** Copyright (C) 2013-2017, NumFOCUS Foundation. ** All rights reserved. ** ** This library is derived, with permission, from the International ** Astronomical Union's "Standards of Fundamental Astronomy" library, ** available from http://www.iausofa.org. ** ** The ERFA version is intended to retain identical functionality to ** the SOFA library, but made distinct through different function and ** file names, as set out in the SOFA license conditions. The SOFA ** original has a role as a reference standard for the IAU and IERS, ** and consequently redistribution is permitted only in its unaltered ** state. The ERFA version is not subject to this restriction and ** therefore can be included in distributions which do not support the ** concept of "read only" software. ** ** Although the intent is to replicate the SOFA API (other than ** replacement of prefix names) and results (with the exception of ** bugs; any that are discovered will be fixed), SOFA is not ** responsible for any errors found in this version of the library. ** ** If you wish to acknowledge the SOFA heritage, please acknowledge ** that you are using a library derived from SOFA, rather than SOFA ** itself. ** ** ** TERMS AND CONDITIONS ** ** Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions ** are met: ** ** 1 Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** ** 2 Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in ** the documentation and/or other materials provided with the ** distribution. ** ** 3 Neither the name of the Standards Of Fundamental Astronomy Board, ** the International Astronomical Union nor the names of its ** contributors may be used to endorse or promote products derived ** from this software without specific prior written permission. ** ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ** POSSIBILITY OF SUCH DAMAGE. ** */