#include "erfa.h"
void eraApio(double sp, double theta,
double elong, double phi, double hm, double xp, double yp,
double refa, double refb,
eraASTROM *astrom)
/*
** - - - - - - - -
** e r a 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.
**
** 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 eraASTROM* 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 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) 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 ERFA function eraSp00.
**
** 2) The geographical coordinates are with respect to the ERFA_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
** eraApio13 can be used instead of the present function. This
** starts from UTC and weather readings etc. and computes suitable
** values using other ERFA 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
**
** 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.
**
** 8) The context structure astrom produced by this function is used by
** eraAtioq and eraAtoiq.
**
** Called:
** eraPvtob position/velocity of terrestrial station
** eraAper astrometry parameters: update ERA
**
** Copyright (C) 2013-2014, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
double sl, cl, 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);
/* Observer's geocentric position and velocity (m, m/s, CIRS). */
eraPvtob(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]) / ERFA_CMPS;
/* Refraction constants. */
astrom->refa = refa;
astrom->refb = refb;
/* Local Earth rotation angle. */
eraAper(theta, astrom);
/* Finished. */
}
/*----------------------------------------------------------------------
**
**
** Copyright (C) 2013-2014, 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,
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** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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**
*/