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/*
*+
* Name:
* palPvobs
* Purpose:
* Position and velocity of an observing station.
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* palPvobs( double p, double h, double stl, double pv[6] )
* Arguments:
* p = double (Given)
* Latitude (geodetic, radians).
* h = double (Given)
* Height above reference spheroid (geodetic, metres).
* stl = double (Given)
* Local apparent sidereal time (radians).
* pv = double[ 6 ] (Returned)
* position/velocity 6-vector (AU, AU/s, true equator
* and equinox of date).
* Description:
* Returns the position and velocity of an observing station.
* Notes:
* - The WGS84 reference ellipsoid is used.
* Authors:
* PTW: Pat Wallace (STFC)
* DSB: David Berry (JAC, Hawaii)
* {enter_new_authors_here}
* History:
* 2012-02-16 (DSB):
* Initial version.
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 1995 Rutherford Appleton Laboratory
* 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 Lesser 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* License along with this program. If not, see
* <http://www.gnu.org/licenses/>.
* Bugs:
* {note_any_bugs_here}
*-
*/
#include "pal.h"
#include "palmac.h"
#include "palmac.h"
#include "pal1sofa.h"
void palPvobs( double p, double h, double stl, double pv[6] ){
/* Local Variables: */
double xyz[3], z, r, s, c, v;
/* Geodetic to geocentric conversion (WGS84 reference ellipsoid). */
eraGd2gc( ERFA_WGS84, 0.0, p, h, xyz );
/* Convert from metres to AU */
r = xyz[ 0 ]/ERFA_DAU;
z = xyz[ 2 ]/ERFA_DAU;
/* Functions of ST. */
s = sin( stl );
c = cos( stl );
/* Speed. */
v = PAL__SR*r;
/* Position. */
pv[ 0 ] = r*c;
pv[ 1 ] = r*s;
pv[ 2 ] = z;
/* Velocity. */
pv[ 3 ] = -v*s;
pv[ 4 ] = v*c;
pv[ 5 ] = 0.0;
}
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