#include "erfa.h" void eraApco(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, eraASTROM *astrom) /* ** - - - - - - - - ** e r a 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. ** ** 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 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) ** ** 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 ERFA_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 eraApco13 can be used instead of the ** present function. This starts from UTC and weather readings etc. ** and computes suitable values using other ERFA 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 ** ** eraApcg eraApcg13 geocentric ICRS <-> GCRS ** eraApci eraApci13 terrestrial ICRS <-> CIRS ** eraApco eraApco13 terrestrial ICRS <-> observed ** eraApcs eraApcs13 space ICRS <-> GCRS ** eraAper eraAper13 terrestrial update Earth rotation ** eraApio eraApio13 terrestrial CIRS <-> observed ** ** Those with names ending in "13" use contemporary ERFA 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 ** eraAtioq, eraAtoiq, eraAtciq* and eraAticq*. ** ** Called: ** eraAper astrometry parameters: update ERA ** eraC2ixys celestial-to-intermediate matrix, given X,Y and s ** eraPvtob position/velocity of terrestrial station ** eraTrxpv product of transpose of r-matrix and pv-vector ** eraApcs astrometry parameters, ICRS-GCRS, space observer ** eraCr copy r-matrix ** ** Copyright (C) 2013-2015, NumFOCUS Foundation. ** Derived, with permission, from the SOFA library. See notes at end of file. */ { 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. */ eraAper(theta, astrom); /* Disable the (redundant) diurnal aberration step. */ astrom->diurab = 0.0; /* CIO based BPN matrix. */ eraC2ixys(x, y, s, r); /* Observer's geocentric position and velocity (m, m/s, CIRS). */ eraPvtob(elong, phi, hm, xp, yp, sp, theta, pvc); /* Rotate into GCRS. */ eraTrxpv(r, pvc, pv); /* ICRS <-> GCRS parameters. */ eraApcs(date1, date2, pv, ebpv, ehp, astrom); /* Store the CIO based BPN matrix. */ eraCr(r, astrom->bpn ); /* Finished. */ } /*---------------------------------------------------------------------- ** ** ** Copyright (C) 2013-2015, 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. ** */