void palSubet ( double rc, double dc, double eq, double *rm, double *dm ) {
double a[3]; /* The E-terms */
double v[3];
double f;
int i;
/* Note the preference for IAU routines */
/* Retrieve the E-terms */
palEtrms( eq, a );
/* Spherical to Cartesian */
iauS2c( rc, dc, v );
/* Include the E-terms */
f = 1.0 + iauPdp( v, a );
for (i=0; i<3; i++) {
v[i] = f*v[i] - a[i];
}
/* Cartesian to spherical */
iauC2s( v, rm, dm );
/* Bring RA into conventional range */
*rm = iauAnp( *rm );
}
void palAddet ( double rm, double dm, double eq, double *rc, double *dc ) {
double a[3]; /* The E-terms */
double v[3];
int i;
/* Note the preference for IAU routines */
/* Retrieve the E-terms */
palEtrms( eq, a );
/* Spherical to Cartesian */
iauS2c( rm, dm, v );
/* Include the E-terms */
for (i=0; i<3; i++) {
v[i] += a[i];
}
/* Cartesian to spherical */
iauC2s( v, rc, dc );
/* Bring RA into conventional range */
*rc = iauAnp( *rc );
}
void palEqgal ( double dr, double dd, double *dl, double *db ) {
double v1[3];
double v2[3];
/*
* L2,B2 system of galactic coordinates
*
* P = 192.25 RA of galactic north pole (mean B1950.0)
* Q = 62.6 inclination of galactic to mean B1950.0 equator
* R = 33 longitude of ascending node
*
* P,Q,R are degrees
*
* Equatorial to galactic rotation matrix (J2000.0), obtained by
* applying the standard FK4 to FK5 transformation, for zero proper
* motion in FK5, to the columns of the B1950 equatorial to
* galactic rotation matrix:
*/
double rmat[3][3] = {
{ -0.054875539726,-0.873437108010,-0.483834985808 },
{ +0.494109453312,-0.444829589425,+0.746982251810 },
{ -0.867666135858,-0.198076386122,+0.455983795705 }
};
/* Spherical to Cartesian */
iauS2c( dr, dd, v1 );
/* Equatorial to Galactic */
iauRxp( rmat, v1, v2 );
/* Cartesian to spherical */
iauC2s( v2, dl, db );
/* Express in conventional ranges */
*dl = iauAnp( *dl );
*db = iauAnpm( *db );
}
void iauP2s(double p[3], double *theta, double *phi, double *r)
/*
** - - - - - - -
** i a u P 2 s
** - - - - - - -
**
** P-vector to spherical polar coordinates.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards Of Fundamental Astronomy) software collection.
**
** Status: vector/matrix support function.
**
** Given:
** p double[3] p-vector
**
** Returned:
** theta double longitude angle (radians)
** phi double latitude angle (radians)
** r double radial distance
**
** Notes:
**
** 1) If P is null, zero theta, phi and r are returned.
**
** 2) At either pole, zero theta is returned.
**
** Called:
** iauC2s p-vector to spherical
** iauPm modulus of p-vector
**
** This revision: 2013 June 18
**
** SOFA release 2013-12-02
**
** Copyright (C) 2013 IAU SOFA Board. See notes at end.
*/
{
iauC2s(p, theta, phi);
*r = iauPm(p);
return;
/*----------------------------------------------------------------------
**
** Copyright (C) 2013
** 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: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauAticqn(double ri, double di, iauASTROM *astrom,
int n, iauLDBODY b[], double *rc, double *dc)
/*
** - - - - - - - - -
** i a u A t i c q n
** - - - - - - - - -
**
** Quick CIRS to ICRS astrometric place transformation, given the star-
** independent astrometry parameters plus a list of light-deflecting
** bodies.
**
** Use of this function is appropriate when efficiency is important and
** where many star positions are all to be transformed for one date.
** The star-independent astrometry parameters can be obtained by
** calling one of the functions iauApci[13], iauApcg[13], iauApco[13]
** or iauApcs[13].
*
* If the only light-deflecting body to be taken into account is the
* Sun, the iauAticq function can be used instead.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards of Fundamental Astronomy) software collection.
**
** Status: support function.
**
** Given:
** ri,di double CIRS RA,Dec (radians)
** 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 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)
** n int number of bodies (Note 3)
** b iauLDBODY[n] data for each of the n bodies (Notes 3,4):
** bm double mass of the body (solar masses, Note 5)
** dl double deflection limiter (Note 6)
** pv [2][3] barycentric PV of the body (au, au/day)
**
** Returned:
** rc,dc double ICRS astrometric RA,Dec (radians)
**
** Notes:
**
** 1) Iterative techniques are used for the aberration and light
** deflection corrections so that the functions iauAticqn and
** iauAtciqn are accurate inverses; even at the edge of the Sun's
** disk the discrepancy is only about 1 nanoarcsecond.
**
** 2) If the only light-deflecting body to be taken into account is the
** Sun, the iauAticq function can be used instead.
**
** 3) The struct b contains n entries, one for each body to be
** considered. If n = 0, no gravitational light deflection will be
** applied, not even for the Sun.
**
** 4) The struct b should include an entry for the Sun as well as for
** any planet or other body to be taken into account. The entries
** should be in the order in which the light passes the body.
**
** 5) In the entry in the b struct for body i, the mass parameter
** b[i].bm can, as required, be adjusted in order to allow for such
** effects as quadrupole field.
**
** 6) The deflection limiter parameter b[i].dl is phi^2/2, where phi is
** the angular separation (in radians) between star and body at
** which limiting is applied. As phi shrinks below the chosen
** threshold, the deflection is artificially reduced, reaching zero
** for phi = 0. Example values suitable for a terrestrial
** observer, together with masses, are as follows:
**
** body i b[i].bm b[i].dl
**
** Sun 1.0 6e-6
** Jupiter 0.00095435 3e-9
** Saturn 0.00028574 3e-10
**
** 7) For efficiency, validation of the contents of the b array is
** omitted. The supplied masses must be greater than zero, the
** position and velocity vectors must be right, and the deflection
** limiter greater than zero.
**
** Called:
** iauS2c spherical coordinates to unit vector
** iauTrxp product of transpose of r-matrix and p-vector
** iauZp zero p-vector
** iauAb stellar aberration
** iauLdn light deflection by n bodies
** iauC2s p-vector to spherical
** iauAnp normalize angle into range +/- pi
**
** This revision: 2013 October 9
**
** SOFA release 2015-02-09
**
** Copyright (C) 2015 IAU SOFA Board. See notes at end.
*/
{
int j, i;
double pi[3], ppr[3], pnat[3], pco[3], w, d[3], before[3], r2, r,
after[3];
/* CIRS RA,Dec to Cartesian. */
iauS2c(ri, di, pi);
/* Bias-precession-nutation, giving GCRS proper direction. */
iauTrxp(astrom->bpn, pi, ppr);
/* Aberration, giving GCRS natural direction. */
iauZp(d);
for (j = 0; j < 2; j++) {
r2 = 0.0;
for (i = 0; i < 3; i++) {
w = ppr[i] - d[i];
before[i] = w;
r2 += w*w;
}
r = sqrt(r2);
for (i = 0; i < 3; i++) {
before[i] /= r;
}
iauAb(before, astrom->v, astrom->em, astrom->bm1, after);
r2 = 0.0;
for (i = 0; i < 3; i++) {
d[i] = after[i] - before[i];
w = ppr[i] - d[i];
pnat[i] = w;
r2 += w*w;
}
r = sqrt(r2);
for (i = 0; i < 3; i++) {
pnat[i] /= r;
}
}
/* Light deflection, giving BCRS coordinate direction. */
iauZp(d);
for (j = 0; j < 5; j++) {
r2 = 0.0;
for (i = 0; i < 3; i++) {
w = pnat[i] - d[i];
before[i] = w;
r2 += w*w;
}
r = sqrt(r2);
for (i = 0; i < 3; i++) {
before[i] /= r;
}
iauLdn(n, b, astrom->eb, before, after);
r2 = 0.0;
for (i = 0; i < 3; i++) {
d[i] = after[i] - before[i];
w = pnat[i] - d[i];
pco[i] = w;
r2 += w*w;
}
r = sqrt(r2);
for (i = 0; i < 3; i++) {
pco[i] /= r;
}
}
/* ICRS astrometric RA,Dec. */
iauC2s(pco, &w, dc);
*rc = iauAnp(w);
/* Finished. */
/*----------------------------------------------------------------------
**
** Copyright (C) 2015
** 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: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauAtciq(double rc, double dc,
double pr, double pd, double px, double rv,
iauASTROM *astrom, double *ri, double *di)
/*
** - - - - - - - - -
** i a u A t c i q
** - - - - - - - - -
**
** Quick ICRS, epoch J2000.0, to CIRS transformation, given precomputed
** star-independent astrometry parameters.
**
** Use of this function is appropriate when efficiency is important and
** where many star positions are to be transformed for one date. The
** star-independent parameters can be obtained by calling one of the
** functions iauApci[13], iauApcg[13], iauApco[13] or iauApcs[13].
**
** If the parallax and proper motions are zero the iauAtciqz function
** can be used instead.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards of Fundamental Astronomy) software collection.
**
** Status: support function.
**
** Given:
** rc,dc double ICRS RA,Dec at J2000.0 (radians)
** pr double RA proper motion (radians/year; Note 3)
** pd double Dec proper motion (radians/year)
** px double parallax (arcsec)
** rv double radial velocity (km/s, +ve if receding)
** 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 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)
**
** Returned:
** ri,di double CIRS RA,Dec (radians)
**
** Notes:
**
** 1) All the vectors are with respect to BCRS axes.
**
** 2) Star data for an epoch other than J2000.0 (for example from the
** Hipparcos catalog, which has an epoch of J1991.25) will require a
** preliminary call to iauPmsafe before use.
**
** 3) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
**
** Called:
** iauPmpx proper motion and parallax
** iauLdsun light deflection by the Sun
** iauAb stellar aberration
** iauRxp product of r-matrix and pv-vector
** iauC2s p-vector to spherical
** iauAnp normalize angle into range 0 to 2pi
**
** This revision: 2013 October 9
**
** SOFA release 2016-05-03
**
** Copyright (C) 2016 IAU SOFA Board. See notes at end.
*/
{
double pco[3], pnat[3], ppr[3], pi[3], w;
/* Proper motion and parallax, giving BCRS coordinate direction. */
iauPmpx(rc, dc, pr, pd, px, rv, astrom->pmt, astrom->eb, pco);
/* Light deflection by the Sun, giving BCRS natural direction. */
iauLdsun(pco, astrom->eh, astrom->em, pnat);
/* Aberration, giving GCRS proper direction. */
iauAb(pnat, astrom->v, astrom->em, astrom->bm1, ppr);
/* Bias-precession-nutation, giving CIRS proper direction. */
iauRxp(astrom->bpn, ppr, pi);
/* CIRS RA,Dec. */
iauC2s(pi, &w, di);
*ri = iauAnp(w);
/* Finished. */
/*----------------------------------------------------------------------
**
** Copyright (C) 2016
** 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: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauFk5hz(double r5, double d5, double date1, double date2,
double *rh, double *dh)
/*
** - - - - - - - - -
** i a u F k 5 h z
** - - - - - - - - -
**
** Transform an FK5 (J2000.0) star position into the system of the
** Hipparcos catalogue, assuming zero Hipparcos proper motion.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards Of Fundamental Astronomy) software collection.
**
** Status: support function.
**
** Given:
** r5 double FK5 RA (radians), equinox J2000.0, at date
** d5 double FK5 Dec (radians), equinox J2000.0, at date
** date1,date2 double TDB date (Notes 1,2)
**
** Returned:
** rh double Hipparcos RA (radians)
** dh double Hipparcos Dec (radians)
**
** Notes:
**
** 1) This function converts a star position from the FK5 system to
** the Hipparcos system, in such a way that the Hipparcos proper
** motion is zero. Because such a star has, in general, a non-zero
** proper motion in the FK5 system, the function requires the date
** at which the position in the FK5 system was determined.
**
** 2) The TT date date1+date2 is a Julian Date, apportioned in any
** convenient way between the two arguments. For example,
** JD(TT)=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.
**
** 3) The FK5 to Hipparcos transformation is modeled as a pure
** rotation and spin; zonal errors in the FK5 catalogue are not
** taken into account.
**
** 4) The position returned by this function is in the Hipparcos
** reference system but at date date1+date2.
**
** 5) See also iauFk52h, iauH2fk5, iauHfk5z.
**
** Called:
** iauS2c spherical coordinates to unit vector
** iauFk5hip FK5 to Hipparcos rotation and spin
** iauSxp multiply p-vector by scalar
** iauRv2m r-vector to r-matrix
** iauTrxp product of transpose of r-matrix and p-vector
** iauPxp vector product of two p-vectors
** iauC2s p-vector to spherical
** iauAnp normalize angle into range 0 to 2pi
**
** Reference:
**
** F.Mignard & M.Froeschle, 2000, Astron.Astrophys. 354, 732-739.
**
** This revision: 2009 December 17
**
** SOFA release 2010-12-01
**
** Copyright (C) 2010 IAU SOFA Board. See notes at end.
*/
{
double t, p5e[3], r5h[3][3], s5h[3], vst[3], rst[3][3], p5[3],
ph[3], w;
/* Interval from given date to fundamental epoch J2000.0 (JY). */
t = - ((date1 - DJ00) + date2) / DJY;
/* FK5 barycentric position vector. */
iauS2c(r5, d5, p5e);
/* FK5 to Hipparcos orientation matrix and spin vector. */
iauFk5hip(r5h, s5h);
/* Accumulated Hipparcos wrt FK5 spin over that interval. */
iauSxp(t, s5h, vst);
/* Express the accumulated spin as a rotation matrix. */
iauRv2m(vst, rst);
/* Derotate the vector's FK5 axes back to date. */
iauTrxp(rst, p5e, p5);
/* Rotate the vector into the Hipparcos system. */
iauRxp(r5h, p5, ph);
/* Hipparcos vector to spherical. */
iauC2s(ph, &w, dh);
*rh = iauAnp(w);
return;
/*----------------------------------------------------------------------
**
** Copyright (C) 2010
** Standards Of Fundamental Astronomy Board
** of the International Astronomical Union.
**
** =====================
** SOFA Software License
** =====================
**
** NOTICE TO USER:
**
** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING 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 name(s) of all routine(s) in your derived work shall not
** include the prefix "iau".
**
** 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. In any published work or commercial products which includes
** results achieved by using the SOFA software, you shall
** acknowledge that the SOFA software was used in obtaining those
** results.
**
** 5. You shall not cause the SOFA software to be brought into
** disrepute, either by misuse, or use for inappropriate tasks, or
** by inappropriate modification.
**
** 6. 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.
**
** 7. 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.
**
** Correspondence concerning SOFA software should be addressed as
** follows:
**
** By email: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauAtoiq(const char *type,
double ob1, double ob2, iauASTROM *astrom,
double *ri, double *di)
/*
** - - - - - - - - -
** i a u A t o i q
** - - - - - - - - -
**
** Quick observed place to CIRS, given the star-independent astrometry
** parameters.
**
** Use of this function is appropriate when efficiency is important and
** where many star positions are all to be transformed for one date.
** The star-independent astrometry parameters can be obtained by
** calling iauApio[13] or iauApco[13].
**
** Status: support function.
**
** Given:
** type char[] type of coordinates: "R", "H" or "A" (Note 1)
** ob1 double observed Az, HA or RA (radians; Az is N=0,E=90)
** ob2 double observed ZD or Dec (radians)
** 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 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)
**
** Returned:
** ri double* CIRS right ascension (CIO-based, radians)
** di double* CIRS declination (radians)
**
** Notes:
**
** 1) "Observed" Az,El means the position that would be seen by a
** perfect geodetically aligned theodolite. This is related to
** the observed HA,Dec via the standard rotation, using the geodetic
** latitude (corrected for polar motion), while the observed HA and
** RA are related simply through the Earth rotation angle and the
** site longitude. "Observed" RA,Dec or HA,Dec thus means the
** position that would be seen by a perfect equatorial with its
** polar axis aligned to the Earth's axis of rotation. By removing
** from the observed place the effects of atmospheric refraction and
** diurnal aberration, the CIRS RA,Dec is obtained.
**
** 2) Only the first character of the type argument is significant.
** "R" or "r" indicates that ob1 and ob2 are the observed right
** ascension and declination; "H" or "h" indicates that they are
** hour angle (west +ve) and declination; anything else ("A" or
** "a" is recommended) indicates that ob1 and ob2 are azimuth (north
** zero, east 90 deg) and zenith distance. (Zenith distance is used
** rather than altitude in order to reflect the fact that no
** allowance is made for depression of the horizon.)
**
** 3) The accuracy of the result is limited by the corrections for
** refraction, which use a simple A*tan(z) + B*tan^3(z) model.
** Providing the meteorological parameters are known accurately and
** there are no gross local effects, the predicted observed
** coordinates should be within 0.05 arcsec (optical) or 1 arcsec
** (radio) for a zenith distance of less than 70 degrees, better
** than 30 arcsec (optical or radio) at 85 degrees and better than
** 20 arcmin (optical) or 30 arcmin (radio) at the horizon.
**
** Without refraction, the complementary functions iauAtioq and
** iauAtoiq are self-consistent to better than 1 microarcsecond all
** over the celestial sphere. With refraction included, consistency
** falls off at high zenith distances, but is still better than
** 0.05 arcsec at 85 degrees.
**
** 4) 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.
**
** Called:
** iauS2c spherical coordinates to unit vector
** iauC2s p-vector to spherical
** iauAnp normalize angle into range 0 to 2pi
**
** This revision: 2013 October 9
**
** SOFA release 2013-12-02
**
** Copyright (C) 2013 IAU SOFA Board. See notes at end.
*/
{
int c;
double c1, c2, sphi, cphi, ce, xaeo, yaeo, zaeo, v[3],
xmhdo, ymhdo, zmhdo, az, sz, zdo, refa, refb, tz, dref,
zdt, xaet, yaet, zaet, xmhda, ymhda, zmhda,
f, xhd, yhd, zhd, xpl, ypl, w, hma;
/* Coordinate type. */
c = (int) type[0];
/* Coordinates. */
c1 = ob1;
c2 = ob2;
/* Sin, cos of latitude. */
sphi = astrom->sphi;
cphi = astrom->cphi;
/* Standardize coordinate type. */
if ( c == 'r' || c == 'R' ) {
c = 'R';
} else if ( c == 'h' || c == 'H' ) {
c = 'H';
} else {
c = 'A';
}
/* If Az,ZD, convert to Cartesian (S=0,E=90). */
if ( c == 'A' ) {
ce = sin(c2);
xaeo = - cos(c1) * ce;
yaeo = sin(c1) * ce;
zaeo = cos(c2);
} else {
/* If RA,Dec, convert to HA,Dec. */
if ( c == 'R' ) c1 = astrom->eral - c1;
/* To Cartesian -HA,Dec. */
iauS2c ( -c1, c2, v );
xmhdo = v[0];
ymhdo = v[1];
zmhdo = v[2];
/* To Cartesian Az,El (S=0,E=90). */
xaeo = sphi*xmhdo - cphi*zmhdo;
yaeo = ymhdo;
zaeo = cphi*xmhdo + sphi*zmhdo;
}
/* Azimuth (S=0,E=90). */
az = ( xaeo != 0.0 || yaeo != 0.0 ) ? atan2(yaeo,xaeo) : 0.0;
/* Sine of observed ZD, and observed ZD. */
sz = sqrt ( xaeo*xaeo + yaeo*yaeo );
zdo = atan2 ( sz, zaeo );
/*
** Refraction
** ----------
*/
/* Fast algorithm using two constant model. */
refa = astrom->refa;
refb = astrom->refb;
tz = sz / zaeo;
dref = ( refa + refb*tz*tz ) * tz;
zdt = zdo + dref;
/* To Cartesian Az,ZD. */
ce = sin(zdt);
xaet = cos(az) * ce;
yaet = sin(az) * ce;
zaet = cos(zdt);
/* Cartesian Az,ZD to Cartesian -HA,Dec. */
xmhda = sphi*xaet + cphi*zaet;
ymhda = yaet;
zmhda = - cphi*xaet + sphi*zaet;
/* Diurnal aberration. */
f = ( 1.0 + astrom->diurab*ymhda );
xhd = f * xmhda;
yhd = f * ( ymhda - astrom->diurab );
zhd = f * zmhda;
/* Polar motion. */
xpl = astrom->xpl;
ypl = astrom->ypl;
w = xpl*xhd - ypl*yhd + zhd;
v[0] = xhd - xpl*w;
v[1] = yhd + ypl*w;
v[2] = w - ( xpl*xpl + ypl*ypl ) * zhd;
/* To spherical -HA,Dec. */
iauC2s(v, &hma, di);
/* Right ascension. */
*ri = iauAnp(astrom->eral + hma);
/* Finished. */
/*----------------------------------------------------------------------
**
** Copyright (C) 2013
** 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: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauLteqec(double epj, double dr, double dd, double *dl, double *db)
/*
** - - - - - - - - - -
** i a u L t e q e c
** - - - - - - - - - -
**
** Transformation from ICRS equatorial coordinates to ecliptic
** coordinates (mean equinox and ecliptic of date) using a long-term
** precession model.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards of Fundamental Astronomy) software collection.
**
** Status: support function.
**
** Given:
** epj double Julian epoch (TT)
** dr,dd double ICRS right ascension and declination (radians)
**
** Returned:
** dl,db double ecliptic longitude and latitude (radians)
**
** 1) No assumptions are made about whether the coordinates represent
** starlight and embody astrometric effects such as parallax or
** aberration.
**
** 2) The transformation is approximately that from mean J2000.0 right
** ascension and declination to ecliptic longitude and latitude
** (mean equinox and ecliptic of date), with only frame bias (always
** less than 25 mas) to disturb this classical picture.
**
** 3) The Vondrak et al. (2011, 2012) 400 millennia precession model
** agrees with the IAU 2006 precession at J2000.0 and stays within
** 100 microarcseconds during the 20th and 21st centuries. It is
** accurate to a few arcseconds throughout the historical period,
** worsening to a few tenths of a degree at the end of the
** +/- 200,000 year time span.
**
** Called:
** iauS2c spherical coordinates to unit vector
** iauLtecm J2000.0 to ecliptic rotation matrix, long term
** iauRxp product of r-matrix and p-vector
** iauC2s unit vector to spherical coordinates
** iauAnp normalize angle into range 0 to 2pi
** iauAnpm normalize angle into range +/- pi
**
** References:
**
** Vondrak, J., Capitaine, N. and Wallace, P., 2011, New precession
** expressions, valid for long time intervals, Astron.Astrophys. 534,
** A22
**
** Vondrak, J., Capitaine, N. and Wallace, P., 2012, New precession
** expressions, valid for long time intervals (Corrigendum),
** Astron.Astrophys. 541, C1
**
** This revision: 2016 February 9
**
** SOFA release 2016-05-03
**
** Copyright (C) 2016 IAU SOFA Board. See notes at end.
*/
{
double rm[3][3], v1[3], v2[3], a, b;
/* Spherical to Cartesian. */
iauS2c(dr, dd, v1);
/* Rotation matrix, ICRS equatorial to ecliptic. */
iauLtecm(epj, rm);
/* The transformation from ICRS to ecliptic. */
iauRxp(rm, v1, v2);
/* Cartesian to spherical. */
iauC2s(v2, &a, &b);
/* Express in conventional ranges. */
*dl = iauAnp(a);
*db = iauAnpm(b);
/*----------------------------------------------------------------------
**
** Copyright (C) 2016
** 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: [email protected]
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}
void iauAtioq(double ri, double di, iauASTROM *astrom,
double *aob, double *zob,
double *hob, double *dob, double *rob)
/*
** - - - - - - - - -
** i a u A t i o q
** - - - - - - - - -
**
** Quick CIRS to observed place transformation.
**
** Use of this function is appropriate when efficiency is important and
** where many star positions are all to be transformed for one date.
** The star-independent astrometry parameters can be obtained by
** calling iauApio[13] or iauApco[13].
**
** This function is part of the International Astronomical Union's
** SOFA (Standards of Fundamental Astronomy) software collection.
**
** Status: support function.
**
** Given:
** ri double CIRS right ascension
** di double CIRS declination
** 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 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)
**
** Returned:
** aob double* observed azimuth (radians: N=0,E=90)
** zob double* observed zenith distance (radians)
** hob double* observed hour angle (radians)
** dob double* observed declination (radians)
** rob double* observed right ascension (CIO-based, radians)
**
** Notes:
**
** 1) This function returns zenith distance rather than altitude in
** order to reflect the fact that no allowance is made for
** depression of the horizon.
**
** 2) The accuracy of the result is limited by the corrections for
** refraction, which use a simple A*tan(z) + B*tan^3(z) model.
** Providing the meteorological parameters are known accurately and
** there are no gross local effects, the predicted observed
** coordinates should be within 0.05 arcsec (optical) or 1 arcsec
** (radio) for a zenith distance of less than 70 degrees, better
** than 30 arcsec (optical or radio) at 85 degrees and better
** than 20 arcmin (optical) or 30 arcmin (radio) at the horizon.
**
** Without refraction, the complementary functions iauAtioq and
** iauAtoiq are self-consistent to better than 1 microarcsecond all
** over the celestial sphere. With refraction included, consistency
** falls off at high zenith distances, but is still better than
** 0.05 arcsec at 85 degrees.
**
** 3) 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.
**
** 4) The CIRS RA,Dec is obtained from a star catalog mean place by
** allowing for space motion, parallax, the Sun's gravitational lens
** effect, annual aberration and precession-nutation. For star
** positions in the ICRS, these effects can be applied by means of
** the iauAtci13 (etc.) functions. Starting from classical "mean
** place" systems, additional transformations will be needed first.
**
** 5) "Observed" Az,El means the position that would be seen by a
** perfect geodetically aligned theodolite. This is obtained from
** the CIRS RA,Dec by allowing for Earth orientation and diurnal
** aberration, rotating from equator to horizon coordinates, and
** then adjusting for refraction. The HA,Dec is obtained by
** rotating back into equatorial coordinates, and is the position
** that would be seen by a perfect equatorial with its polar axis
** aligned to the Earth's axis of rotation. Finally, the RA is
** obtained by subtracting the HA from the local ERA.
**
** 6) The star-independent CIRS-to-observed-place parameters in ASTROM
** may be computed with iauApio[13] or iauApco[13]. If nothing has
** changed significantly except the time, iauAper[13] may be used to
** perform the requisite adjustment to the astrom structure.
**
** Called:
** iauS2c spherical coordinates to unit vector
** iauC2s p-vector to spherical
** iauAnp normalize angle into range 0 to 2pi
**
** This revision: 2013 December 5
**
** SOFA release 2015-02-09
**
** Copyright (C) 2015 IAU SOFA Board. See notes at end.
*/
{
/* Minimum cos(alt) and sin(alt) for refraction purposes */
const double CELMIN = 1e-6;
const double SELMIN = 0.05;
double v[3], x, y, z, xhd, yhd, zhd, f, xhdt, yhdt, zhdt,
xaet, yaet, zaet, azobs, r, tz, w, del, cosdel,
xaeo, yaeo, zaeo, zdobs, hmobs, dcobs, raobs;
/*--------------------------------------------------------------------*/
/* CIRS RA,Dec to Cartesian -HA,Dec. */
iauS2c(ri-astrom->eral, di, v);
x = v[0];
y = v[1];
z = v[2];
/* Polar motion. */
xhd = x + astrom->xpl*z;
yhd = y - astrom->ypl*z;
zhd = z - astrom->xpl*x + astrom->ypl*y;
/* Diurnal aberration. */
f = ( 1.0 - astrom->diurab*yhd );
xhdt = f * xhd;
yhdt = f * ( yhd + astrom->diurab );
zhdt = f * zhd;
/* Cartesian -HA,Dec to Cartesian Az,El (S=0,E=90). */
xaet = astrom->sphi*xhdt - astrom->cphi*zhdt;
yaet = yhdt;
zaet = astrom->cphi*xhdt + astrom->sphi*zhdt;
/* Azimuth (N=0,E=90). */
azobs = ( xaet != 0.0 || yaet != 0.0 ) ? atan2(yaet,-xaet) : 0.0;
/* ---------- */
/* Refraction */
/* ---------- */
/* Cosine and sine of altitude, with precautions. */
r = sqrt(xaet*xaet + yaet*yaet);
r = r > CELMIN ? r : CELMIN;
z = zaet > SELMIN ? zaet : SELMIN;
/* A*tan(z)+B*tan^3(z) model, with Newton-Raphson correction. */
tz = r/z;
w = astrom->refb*tz*tz;
del = ( astrom->refa + w ) * tz /
( 1.0 + ( astrom->refa + 3.0*w ) / ( z*z ) );
/* Apply the change, giving observed vector. */
cosdel = 1.0 - del*del/2.0;
f = cosdel - del*z/r;
xaeo = xaet*f;
yaeo = yaet*f;
zaeo = cosdel*zaet + del*r;
/* Observed ZD. */
zdobs = atan2(sqrt(xaeo*xaeo+yaeo*yaeo), zaeo);
/* Az/El vector to HA,Dec vector (both right-handed). */
v[0] = astrom->sphi*xaeo + astrom->cphi*zaeo;
v[1] = yaeo;
v[2] = - astrom->cphi*xaeo + astrom->sphi*zaeo;
/* To spherical -HA,Dec. */
iauC2s ( v, &hmobs, &dcobs );
/* Right ascension (with respect to CIO). */
raobs = astrom->eral + hmobs;
/* Return the results. */
*aob = iauAnp(azobs);
*zob = zdobs;
*hob = -hmobs;
*dob = dcobs;
*rob = iauAnp(raobs);
/* Finished. */
/*----------------------------------------------------------------------
**
** Copyright (C) 2015
** 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
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**
** e) These requirements must be reproduced intact in any source
** distribution and shall apply to anyone to whom you have
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** 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
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**
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** 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: [email protected]
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**
**--------------------------------------------------------------------*/
}
