#include "sofa.h" void iauAtci13(double rc, double dc, double pr, double pd, double px, double rv, double date1, double date2, double *ri, double *di, double *eo) /* ** - - - - - - - - - - ** i a u A t c i 1 3 ** - - - - - - - - - - ** ** Transform ICRS star data, epoch J2000.0, to CIRS. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** Given: ** rc double ICRS right ascension at J2000.0 (radians, Note 1) ** dc double ICRS declination at J2000.0 (radians, Note 1) ** pr double RA proper motion (radians/year; Note 2) ** pd double Dec proper motion (radians/year) ** px double parallax (arcsec) ** rv double radial velocity (km/s, +ve if receding) ** date1 double TDB as a 2-part... ** date2 double ...Julian Date (Note 3) ** ** Returned: ** ri,di double* CIRS geocentric RA,Dec (radians) ** eo double* equation of the origins (ERA-GST, Note 5) ** ** 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 iauPmsafe before use. ** ** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. ** ** 3) The TDB date date1+date2 is a Julian Date, apportioned in any ** convenient way between the two arguments. For example, ** JD(TDB)=2450123.7 could be expressed in any of these ways, among ** others: ** ** date1 date2 ** ** 2450123.7 0.0 (JD method) ** 2451545.0 -1421.3 (J2000 method) ** 2400000.5 50123.2 (MJD method) ** 2450123.5 0.2 (date & time method) ** ** The JD method is the most natural and convenient to use in cases ** where the loss of several decimal digits of resolution is ** acceptable. The J2000 method is best matched to the way the ** argument is handled internally and will deliver the optimum ** resolution. The MJD method and the date & time methods are both ** good compromises between resolution and convenience. For most ** applications of this function the choice will not be at all ** critical. ** ** TT can be used instead of TDB without any significant impact on ** accuracy. ** ** 4) The available accuracy is better than 1 milliarcsecond, limited ** mainly by the precession-nutation model that is used, namely ** IAU 2000A/2006. Very close to solar system bodies, additional ** errors of up to several milliarcseconds can occur because of ** unmodeled light deflection; however, the Sun's contribution is ** taken into account, to first order. The accuracy limitations of ** the SOFA function iauEpv00 (used to compute Earth position and ** velocity) can contribute aberration errors of up to ** 5 microarcseconds. Light deflection at the Sun's limb is ** uncertain at the 0.4 mas level. ** ** 5) Should the transformation to (equinox based) apparent place be ** required rather than (CIO based) intermediate place, subtract the ** equation of the origins from the returned right ascension: ** RA = RI - EO. (The iauAnp function can then be applied, as ** required, to keep the result in the conventional 0-2pi range.) ** ** Called: ** iauApci13 astrometry parameters, ICRS-CIRS, 2013 ** iauAtciq quick ICRS to CIRS ** ** This revision: 2017 March 12 ** ** SOFA release 2020-07-21 ** ** Copyright (C) 2020 IAU SOFA Board. See notes at end. */ { /* Star-independent astrometry parameters */ iauASTROM astrom; /* The transformation parameters. */ iauApci13(date1, date2, &astrom, eo); /* ICRS (epoch J2000.0) to CIRS. */ iauAtciq(rc, dc, pr, pd, px, rv, &astrom, ri, di); /* 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 ** **--------------------------------------------------------------------*/ }