diff options
Diffstat (limited to 'ast/erfa/apio.c')
| -rw-r--r-- | ast/erfa/apio.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/ast/erfa/apio.c b/ast/erfa/apio.c new file mode 100644 index 0000000..ebc5569 --- /dev/null +++ b/ast/erfa/apio.c @@ -0,0 +1,213 @@ +#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) 2013-2016, 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) 2013-2016, 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. +** +*/ |