#include "sofa.h" void iauApco(double date1, double date2, double ebpv[2][3], double ehp[3], double x, double y, double s, double theta, double elong, double phi, double hm, double xp, double yp, double sp, double refa, double refb, iauASTROM *astrom) /* ** - - - - - - - - ** i a u A p c o ** - - - - - - - - ** ** For a terrestrial observer, prepare star-independent astrometry ** parameters for transformations between ICRS and observed ** coordinates. The caller supplies the Earth ephemeris, the Earth ** rotation information and the refraction constants as well as the ** site coordinates. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** Given: ** date1 double TDB as a 2-part... ** date2 double ...Julian Date (Note 1) ** ebpv double[2][3] Earth barycentric PV (au, au/day, Note 2) ** ehp double[3] Earth heliocentric P (au, Note 2) ** x,y double CIP X,Y (components of unit vector) ** s double the CIO locator s (radians) ** theta double Earth rotation angle (radians) ** elong double longitude (radians, east +ve, Note 3) ** phi double latitude (geodetic, radians, Note 3) ** hm double height above ellipsoid (m, geodetic, Note 3) ** xp,yp double polar motion coordinates (radians, Note 4) ** sp double the TIO locator s' (radians, Note 4) ** refa double refraction constant A (radians, Note 5) ** refb double refraction constant B (radians, Note 5) ** ** Returned: ** astrom iauASTROM* 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) ** ** Notes: ** ** 1) 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. ** ** 2) The vectors eb, eh, and all the astrom vectors, are with respect ** to BCRS axes. ** ** 3) The geographical coordinates are with respect to the WGS84 ** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN ** CONVENTION: the longitude required by the present function is ** right-handed, i.e. east-positive, in accordance with geographical ** convention. ** ** 4) xp and yp are the coordinates (in radians) of the Celestial ** Intermediate Pole with respect to the International Terrestrial ** Reference System (see IERS Conventions), measured along the ** meridians 0 and 90 deg west respectively. sp is the TIO locator ** s', in radians, which positions the Terrestrial Intermediate ** Origin on the equator. For many applications, xp, yp and ** (especially) sp can be set to zero. ** ** Internally, the polar motion is stored in a form rotated onto the ** local meridian. ** ** 5) The refraction constants refa and refb are for use in a ** dZ = A*tan(Z)+B*tan^3(Z) model, where Z is the observed ** (i.e. refracted) zenith distance and dZ is the amount of ** refraction. ** ** 6) It is advisable to take great care with units, as even unlikely ** values of the input parameters are accepted and processed in ** accordance with the models used. ** ** 7) In cases where the caller does not wish to provide the Earth ** Ephemeris, the Earth rotation information and refraction ** constants, the function iauApco13 can be used instead of the ** present function. This starts from UTC and weather readings etc. ** and computes suitable values using other SOFA functions. ** ** 8) This is one of several functions that inserts into the astrom ** structure star-independent parameters needed for the chain of ** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed. ** ** The various functions support different classes of observer and ** portions of the transformation chain: ** ** functions observer transformation ** ** iauApcg iauApcg13 geocentric ICRS <-> GCRS ** iauApci iauApci13 terrestrial ICRS <-> CIRS ** iauApco iauApco13 terrestrial ICRS <-> observed ** iauApcs iauApcs13 space ICRS <-> GCRS ** iauAper iauAper13 terrestrial update Earth rotation ** iauApio iauApio13 terrestrial CIRS <-> observed ** ** Those with names ending in "13" use contemporary SOFA models to ** compute the various ephemerides. The others accept ephemerides ** supplied by the caller. ** ** The transformation from ICRS to GCRS covers space motion, ** parallax, light deflection, and aberration. From GCRS to CIRS ** comprises frame bias and precession-nutation. From CIRS to ** observed takes account of Earth rotation, polar motion, diurnal ** aberration and parallax (unless subsumed into the ICRS <-> GCRS ** transformation), and atmospheric refraction. ** ** 9) The context structure astrom produced by this function is used by ** iauAtioq, iauAtoiq, iauAtciq* and iauAticq*. ** ** Called: ** iauAper astrometry parameters: update ERA ** iauC2ixys celestial-to-intermediate matrix, given X,Y and s ** iauPvtob position/velocity of terrestrial station ** iauTrxpv product of transpose of r-matrix and pv-vector ** iauApcs astrometry parameters, ICRS-GCRS, space observer ** iauCr copy r-matrix ** ** This revision: 2013 October 9 ** ** SOFA release 2018-01-30 ** ** Copyright (C) 2018 IAU SOFA Board. See notes at end. */ { double sl, cl, r[3][3], pvc[2][3], pv[2][3]; /* Longitude with adjustment for TIO locator s'. */ astrom->along = elong + sp; /* Polar motion, rotated onto the local meridian. */ sl = sin(astrom->along); cl = cos(astrom->along); astrom->xpl = xp*cl - yp*sl; astrom->ypl = xp*sl + yp*cl; /* Functions of latitude. */ astrom->sphi = sin(phi); astrom->cphi = cos(phi); /* Refraction constants. */ astrom->refa = refa; astrom->refb = refb; /* Local Earth rotation angle. */ iauAper(theta, astrom); /* Disable the (redundant) diurnal aberration step. */ astrom->diurab = 0.0; /* CIO based BPN matrix. */ iauC2ixys(x, y, s, r); /* Observer's geocentric position and velocity (m, m/s, CIRS). */ iauPvtob(elong, phi, hm, xp, yp, sp, theta, pvc); /* Rotate into GCRS. */ iauTrxpv(r, pvc, pv); /* ICRS <-> GCRS parameters. */ iauApcs(date1, date2, pv, ebpv, ehp, astrom); /* Store the CIO based BPN matrix. */ iauCr(r, astrom->bpn ); /* Finished. */ /*---------------------------------------------------------------------- ** ** Copyright (C) 2018 ** 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 ** **--------------------------------------------------------------------*/ }