#include "sofa.h" void iauPmpx(double rc, double dc, double pr, double pd, double px, double rv, double pmt, double pob[3], double pco[3]) /* ** - - - - - - - - ** i a u P m p x ** - - - - - - - - ** ** Proper motion and parallax. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** Given: ** rc,dc double ICRS RA,Dec at catalog epoch (radians) ** pr double RA proper motion (radians/year; Note 1) ** pd double Dec proper motion (radians/year) ** px double parallax (arcsec) ** rv double radial velocity (km/s, +ve if receding) ** pmt double proper motion time interval (SSB, Julian years) ** pob double[3] SSB to observer vector (au) ** ** Returned: ** pco double[3] coordinate direction (BCRS unit vector) ** ** Notes: ** ** 1) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. ** ** 2) The proper motion time interval is for when the starlight ** reaches the solar system barycenter. ** ** 3) To avoid the need for iteration, the Roemer effect (i.e. the ** small annual modulation of the proper motion coming from the ** changing light time) is applied approximately, using the ** direction of the star at the catalog epoch. ** ** References: ** ** 1984 Astronomical Almanac, pp B39-B41. ** ** Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to ** the Astronomical Almanac, 3rd ed., University Science Books ** (2013), Section 7.2. ** ** Called: ** iauPdp scalar product of two p-vectors ** iauPn decompose p-vector into modulus and direction ** ** This revision: 2013 October 9 ** ** SOFA release 2020-07-21 ** ** Copyright (C) 2020 IAU SOFA Board. See notes at end. */ { /* Km/s to au/year */ const double VF = DAYSEC*DJM/DAU; /* Light time for 1 au, Julian years */ const double AULTY = AULT/DAYSEC/DJY; int i; double sr, cr, sd, cd, x, y, z, p[3], dt, pxr, w, pdz, pm[3]; /* Spherical coordinates to unit vector (and useful functions). */ sr = sin(rc); cr = cos(rc); sd = sin(dc); cd = cos(dc); p[0] = x = cr*cd; p[1] = y = sr*cd; p[2] = z = sd; /* Proper motion time interval (y) including Roemer effect. */ dt = pmt + iauPdp(p,pob)*AULTY; /* Space motion (radians per year). */ pxr = px * DAS2R; w = VF * rv * pxr; pdz = pd * z; pm[0] = - pr*y - pdz*cr + w*x; pm[1] = pr*x - pdz*sr + w*y; pm[2] = pd*cd + w*z; /* Coordinate direction of star (unit vector, BCRS). */ for (i = 0; i < 3; i++) { p[i] += dt*pm[i] - pxr*pob[i]; } iauPn(p, &w, pco); /* Finished. */ /*---------------------------------------------------------------------- ** ** Copyright (C) 2020 ** Standards Of Fundamental Astronomy Board ** of the International Astronomical Union. ** ** ===================== ** SOFA Software License ** ===================== ** ** NOTICE TO USER: ** ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND ** CONDITIONS WHICH APPLY TO ITS USE. ** ** 1. The Software is owned by the IAU SOFA Board ("SOFA"). ** ** 2. Permission is granted to anyone to use the SOFA software for any ** purpose, including commercial applications, free of charge and ** without payment of royalties, subject to the conditions and ** restrictions listed below. ** ** 3. You (the user) may copy and distribute SOFA source code to others, ** and use and adapt its code and algorithms in your own software, ** on a world-wide, royalty-free basis. That portion of your ** distribution that does not consist of intact and unchanged copies ** of SOFA source code files is a "derived work" that must comply ** with the following requirements: ** ** a) Your work shall be marked or carry a statement that it ** (i) uses routines and computations derived by you from ** software provided by SOFA under license to you; and ** (ii) does not itself constitute software provided by and/or ** endorsed by SOFA. ** ** b) The source code of your derived work must contain descriptions ** of how the derived work is based upon, contains and/or differs ** from the original SOFA software. ** ** c) The names of all routines in your derived work shall not ** include the prefix "iau" or "sofa" or trivial modifications ** thereof such as changes of case. ** ** d) The origin of the SOFA components of your derived work must ** not be misrepresented; you must not claim that you wrote the ** original software, nor file a patent application for SOFA ** software or algorithms embedded in the SOFA software. ** ** e) These requirements must be reproduced intact in any source ** distribution and shall apply to anyone to whom you have ** granted a further right to modify the source code of your ** derived work. ** ** Note that, as originally distributed, the SOFA software is ** intended to be a definitive implementation of the IAU standards, ** and consequently third-party modifications are discouraged. All ** variations, no matter how minor, must be explicitly marked as ** such, as explained above. ** ** 4. You shall not cause the SOFA software to be brought into ** disrepute, either by misuse, or use for inappropriate tasks, or ** by inappropriate modification. ** ** 5. The SOFA software is provided "as is" and SOFA makes no warranty ** as to its use or performance. SOFA does not and cannot warrant ** the performance or results which the user may obtain by using the ** SOFA software. SOFA makes no warranties, express or implied, as ** to non-infringement of third party rights, merchantability, or ** fitness for any particular purpose. In no event will SOFA be ** liable to the user for any consequential, incidental, or special ** damages, including any lost profits or lost savings, even if a ** SOFA representative has been advised of such damages, or for any ** claim by any third party. ** ** 6. The provision of any version of the SOFA software under the terms ** and conditions specified herein does not imply that future ** versions will also be made available under the same terms and ** conditions. * ** In any published work or commercial product which uses the SOFA ** software directly, acknowledgement (see www.iausofa.org) is ** appreciated. ** ** Correspondence concerning SOFA software should be addressed as ** follows: ** ** By email: sofa@ukho.gov.uk ** By post: IAU SOFA Center ** HM Nautical Almanac Office ** UK Hydrographic Office ** Admiralty Way, Taunton ** Somerset, TA1 2DN ** United Kingdom ** **--------------------------------------------------------------------*/ }