#include "sofa.h" #include "sofam.h" void iauApio(double sp, double theta, double elong, double phi, double hm, double xp, double yp, double refa, double refb, iauASTROM *astrom) /* ** - - - - - - - - ** i a u A p i o ** - - - - - - - - ** ** For a terrestrial observer, prepare star-independent astrometry ** parameters for transformations between CIRS and observed ** coordinates. The caller supplies the Earth orientation 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: ** sp double the TIO locator s' (radians, Note 1) ** theta double Earth rotation angle (radians) ** elong double longitude (radians, east +ve, Note 2) ** phi double geodetic latitude (radians, Note 2) ** hm double height above ellipsoid (m, geodetic Note 2) ** xp,yp double polar motion coordinates (radians, Note 3) ** refa double refraction constant A (radians, Note 4) ** refb double refraction constant B (radians, Note 4) ** ** Returned: ** astrom iauASTROM* star-independent astrometry parameters: ** pmt double unchanged ** eb double[3] unchanged ** eh double[3] unchanged ** em double unchanged ** v double[3] unchanged ** bm1 double unchanged ** bpn double[3][3] unchanged ** along double adjusted longitude (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) sp, the TIO locator s', is a tiny quantity needed only by the ** most precise applications. It can either be set to zero or ** predicted using the SOFA function iauSp00. ** ** 2) The geographical coordinates are with respect to the WGS84 ** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the ** longitude required by the present function is east-positive ** (i.e. right-handed), in accordance with geographical convention. ** ** 3) The polar motion xp,yp can be obtained from IERS bulletins. The ** values are the coordinates (in radians) of the Celestial ** Intermediate Pole with respect to the International Terrestrial ** Reference System (see IERS Conventions 2003), measured along the ** meridians 0 and 90 deg west respectively. For many applications, ** xp and yp can be set to zero. ** ** Internally, the polar motion is stored in a form rotated onto the ** local meridian. ** ** 4) 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. ** ** 5) 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. ** ** 6) In cases where the caller does not wish to provide the Earth ** rotation information and refraction constants, the function ** iauApio13 can be used instead of the present function. This ** starts from UTC and weather readings etc. and computes suitable ** values using other SOFA functions. ** ** 7) 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. ** ** 8) The context structure astrom produced by this function is used by ** iauAtioq and iauAtoiq. ** ** Called: ** iauIr initialize r-matrix to identity ** iauRz rotate around Z-axis ** iauRy rotate around Y-axis ** iauRx rotate around X-axis ** iauAnpm normalize angle into range +/- pi ** iauPvtob position/velocity of terrestrial station ** ** This revision: 2021 February 24 ** ** SOFA release 2021-05-12 ** ** Copyright (C) 2021 IAU SOFA Board. See notes at end. */ { double r[3][3], a, b, eral, c, pv[2][3]; /* Form the rotation matrix, CIRS to apparent [HA,Dec]. */ iauIr(r); iauRz(theta+sp, r); iauRy(-xp, r); iauRx(-yp, r); iauRz(elong, r); /* Solve for local Earth rotation angle. */ a = r[0][0]; b = r[0][1]; eral = ( a != 0.0 || b != 0.0 ) ? atan2(b, a) : 0.0; astrom->eral = eral; /* Solve for polar motion [X,Y] with respect to local meridian. */ a = r[0][0]; c = r[0][2]; astrom->xpl = atan2(c, sqrt(a*a+b*b)); a = r[1][2]; b = r[2][2]; astrom->ypl = ( a != 0.0 || b != 0.0 ) ? -atan2(a, b) : 0.0; /* Adjusted longitude. */ astrom->along = iauAnpm(eral - theta); /* Functions of latitude. */ astrom->sphi = sin(phi); astrom->cphi = cos(phi); /* Observer's geocentric position and velocity (m, m/s, CIRS). */ iauPvtob(elong, phi, hm, xp, yp, sp, theta, pv); /* Magnitude of diurnal aberration vector. */ astrom->diurab = sqrt(pv[1][0]*pv[1][0]+pv[1][1]*pv[1][1]) / CMPS; /* Refraction constants. */ astrom->refa = refa; astrom->refb = refb; /* Finished. */ /*---------------------------------------------------------------------- ** ** Copyright (C) 2021 ** 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 ** **--------------------------------------------------------------------*/ }