#include "sofa.h"
#include "sofam.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 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) 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.
**
** The adjusted longitude stored in the astrom array takes into
** account the TIO locator and polar motion.
**
** 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:
** 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
** 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: 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, pvc[2][3], 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);
/* Refraction constants. */
astrom->refa = refa;
astrom->refb = refb;
/* 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) 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
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**
** 3. You (the user) may copy and distribute SOFA source code to others,
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**
** a) Your work shall be marked or carry a statement that it
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**
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**
** c) The names of all routines in your derived work shall not
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** Note that, as originally distributed, the SOFA software is
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**
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**
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*
** In any published work or commercial product which uses the SOFA
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** follows:
**
** By email: sofa@ukho.gov.uk
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**
**--------------------------------------------------------------------*/
}