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/*
*+
* Name:
* palOapqk
* Purpose:
* Quick observed to apparent place
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* void palOapqk ( const char *type, double ob1, double ob2,
* const double aoprms[14], double *rap, double *dap );
* Arguments:
* Quick observed to apparent place.
* Description:
* type = const char * (Given)
* Type of coordinates  'R', 'H' or 'A' (see below)
* ob1 = double (Given)
* Observed Az, HA or RA (radians; Az is N=0;E=90)
* ob2 = double (Given)
* Observed ZD or Dec (radians)
* aoprms = const double [14] (Given)
* Starindependent apparenttoobserved parameters.
* See palAopqk for details.
* rap = double * (Given)
* Geocentric apparent right ascension
* dap = double * (Given)
* Geocentric apparent declination
* Authors:
* PTW: Patrick T. Wallace
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* Notes:
*  Only the first character of the TYPE argument is significant.
* 'R' or 'r' indicates that OBS1 and OBS2 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 OBS1 and OBS2 are azimuth
* (north zero, east 90 deg) and zenith distance. (Zenith distance
* is used rather than elevation in order to reflect the fact that
* no allowance is made for depression of the horizon.)
*
*  The accuracy of the result is limited by the corrections for
* refraction. Providing the meteorological parameters are
* known accurately and there are no gross local effects, the
* predicted apparent RA,Dec should be within about 0.1 arcsec
* for a zenith distance of less than 70 degrees. Even at a
* topocentric zenith distance of 90 degrees, the accuracy in
* elevation should be better than 1 arcmin; useful results
* are available for a further 3 degrees, beyond which the
* palREFRO routine returns a fixed value of the refraction.
* The complementary routines palAop (or palAopqk) and palOap
* (or palOapqk) are selfconsistent to better than 1 micro
* arcsecond all over the celestial sphere.
*
*  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.
*
*  "Observed" Az,El means the position that would be seen by a
* perfect theodolite located at the observer. 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 local
* apparent ST. "Observed" RA,Dec or HA,Dec thus means the
* position that would be seen by a perfect equatorial located
* at the observer and with its polar axis aligned to the
* Earth's axis of rotation (n.b. not to the refracted pole).
* By removing from the observed place the effects of
* atmospheric refraction and diurnal aberration, the
* geocentric apparent RA,Dec is obtained.
*
*  Frequently, mean rather than apparent RA,Dec will be required,
* in which case further transformations will be necessary. The
* palAmp etc routines will convert the apparent RA,Dec produced
* by the present routine into an "FK5" (J2000) mean place, by
* allowing for the Sun's gravitational lens effect, annual
* aberration, nutation and precession. Should "FK4" (1950)
* coordinates be needed, the routines palFk524 etc will also
* need to be applied.
*
*  To convert to apparent RA,Dec the coordinates read from a
* real telescope, corrections would have to be applied for
* encoder zero points, gear and encoder errors, tube flexure,
* the position of the rotator axis and the pointing axis
* relative to it, nonperpendicularity between the mounting
* axes, and finally for the tilt of the azimuth or polar axis
* of the mounting (with appropriate corrections for mount
* flexures). Some telescopes would, of course, exhibit other
* properties which would need to be accounted for at the
* appropriate point in the sequence.
*
*  The starindependent apparenttoobservedplace parameters
* in AOPRMS may be computed by means of the palAoppa routine.
* If nothing has changed significantly except the time, the
* palAoppat routine may be used to perform the requisite
* partial recomputation of AOPRMS.
*
*  The azimuths etc used by the present routine are with respect
* to the celestial pole. Corrections from the terrestrial pole
* can be computed using palPolmo.
* History:
* 20120827 (TIMJ):
* Initial version, direct copy of Fortran SLA
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 2004 Patrick T. Wallace
* Copyright (C) 2012 Science and Technology Facilities Council.
* All Rights Reserved.
* Licence:
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 021101301, USA.
* Bugs:
* {note_any_bugs_here}
*
*/
#include <math.h>
#include "pal.h"
#include "palmac.h"
void palOapqk ( const char *type, double ob1, double ob2, const double aoprms[14],
double *rap, double *dap ) {
/* breakpoint for fast/slow refraction algorithm:
* zd greater than arctan(4), (see palRefco routine)
* or vector z less than cosine(arctan(z)) = 1/sqrt(17) */
const double zbreak = 0.242535625;
char c;
double c1,c2,sphi,cphi,st,ce,xaeo,yaeo,zaeo,v[3],
xmhdo,ymhdo,zmhdo,az,sz,zdo,tz,dref,zdt,
xaet,yaet,zaet,xmhda,ymhda,zmhda,diurab,f,hma;
/* coordinate type */
c = type[0];
/* coordinates */
c1 = ob1;
c2 = ob2;
/* sin, cos of latitude */
sphi = aoprms[1];
cphi = aoprms[2];
/* local apparent sidereal time */
st = aoprms[13];
/* standardise 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 = stc1;
}
/* to cartesian ha,dec */
palDcs2c( c1, c2, v );
xmhdo = v[0];
ymhdo = v[1];
zmhdo = v[2];
/* to cartesian az,el (s=0,e=90) */
xaeo = sphi*xmhdocphi*zmhdo;
yaeo = ymhdo;
zaeo = cphi*xmhdo+sphi*zmhdo;
}
/* azimuth (s=0,e=90) */
if (xaeo != 0.0  yaeo != 0.0) {
az = atan2(yaeo,xaeo);
} else {
az = 0.0;
}
/* sine of observed zd, and observed zd */
sz = sqrt(xaeo*xaeo+yaeo*yaeo);
zdo = atan2(sz,zaeo);
/*
* refraction
*  */
/* large zenith distance? */
if (zaeo >= zbreak) {
/* fast algorithm using two constant model */
tz = sz/zaeo;
dref = (aoprms[10]+aoprms[11]*tz*tz)*tz;
} else {
/* rigorous algorithm for large zd */
palRefro(zdo,aoprms[4],aoprms[5],aoprms[6],aoprms[7],
aoprms[8],aoprms[0],aoprms[9],1e8,&dref);
}
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 */
diurab = aoprms[3];
f = (1.0diurab*ymhda);
v[0] = f*xmhda;
v[1] = f*(ymhda+diurab);
v[2] = f*zmhda;
/* to spherical ha,dec */
palDcc2s(v,&hma,dap);
/* Right Ascension */
*rap = palDranrm(st+hma);
}
