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Diffstat (limited to 'ast/erfa/atciqn.c')
| -rw-r--r-- | ast/erfa/atciqn.c | 191 |
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diff --git a/ast/erfa/atciqn.c b/ast/erfa/atciqn.c new file mode 100644 index 0000000..0ad89a0 --- /dev/null +++ b/ast/erfa/atciqn.c @@ -0,0 +1,191 @@ +#include "erfa.h" + +void eraAtciqn(double rc, double dc, double pr, double pd, + double px, double rv, eraASTROM *astrom, + int n, eraLDBODY b[], double *ri, double *di) +/* +** - - - - - - - - - - +** e r a A t c i q n +** - - - - - - - - - - +** +** Quick ICRS, epoch J2000.0, to CIRS transformation, given precomputed +** 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 to be transformed for one date. The +** star-independent 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 eraAtciq function can be used instead. If in addition the +** parallax and proper motions are zero, the eraAtciqz function can be +** used. +** +** Given: +** rc,dc double ICRS RA,Dec at J2000.0 (radians) +** pr double RA proper motion (radians/year; Note 3) +** pd double Dec proper motion (radians/year) +** px double parallax (arcsec) +** rv double radial velocity (km/s, +ve if receding) +** 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: +** ri,di double CIRS RA,Dec (radians) +** +** Notes: +** +** 1) Star data for an epoch other than J2000.0 (for example from the +** Hipparcos catalog, which has an epoch of J1991.25) will require a +** preliminary call to eraPmsafe before use. +** +** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. +** +** 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: +** eraPmpx proper motion and parallax +** eraLdn light deflection by n bodies +** eraAb stellar aberration +** eraRxp product of r-matrix and pv-vector +** eraC2s p-vector to spherical +** eraAnp normalize angle into range 0 to 2pi +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + double pco[3], pnat[3], ppr[3], pi[3], w; + + +/* Proper motion and parallax, giving BCRS coordinate direction. */ + eraPmpx(rc, dc, pr, pd, px, rv, astrom->pmt, astrom->eb, pco); + +/* Light deflection, giving BCRS natural direction. */ + eraLdn(n, b, astrom->eb, pco, pnat); + +/* Aberration, giving GCRS proper direction. */ + eraAb(pnat, astrom->v, astrom->em, astrom->bm1, ppr); + +/* Bias-precession-nutation, giving CIRS proper direction. */ + eraRxp(astrom->bpn, ppr, pi); + +/* CIRS RA,Dec. */ + eraC2s(pi, &w, di); + *ri = eraAnp(w); + +/* Finished. */ + +} +/*---------------------------------------------------------------------- +** +** +** Copyright (C) 2013-2016, 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. +** +*/ |