nova.apparent_position source code

1 /*
2  *  This library is free software; you can redistribute it and/or
3  *  modify it under the terms of the GNU Lesser General Public
4  *  License as published by the Free Software Foundation; either
5  *  version 2 of the License, or (at your option) any later version.
6  *
7  *  This library is distributed in the hope that it will be useful,
8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
10  *  Lesser General Public License for more details.
11  *
12  *  You should have received a copy of the GNU General Public License
13  *  along with this program; if not, write to the Free Software
14  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
15  *
16  *  Copyright (C) 2000 - 2005 Liam Girdwood  <lgirdwood@gmail.com>
17  */
18 
19 module nova.apparent_position;
20 
21 import nova.proper_motion;
22 import nova.aberration;
23 import nova.precession;
24 import nova.nutation;
25 import nova.ln_types;
26 
27 extern (C) {
28 
29 /*
30 ** Apparent place of an Object
31 */
32 
33 /*! \fn void ln_get_apparent_posn(struct ln_equ_posn *mean_position, struct ln_equ_posn *proper_motion, double JD, struct ln_equ_posn *position)
34 * \param mean_position Mean position of object, epoch J2000
35 * \param proper_motion Proper motion of object
36 * \param JD Julian Day
37 * \param position Pointer to store new object position
38 *
39 * Calculate the apparent equatorial position of a star from its mean equatorial position.
40 * This function takes into account the effects of proper motion, precession, nutation,
41 * annual aberration when calculating the stars apparent position. The effects of annual
42 * parallax and the gravitational deflection of light (Einstein effect) are NOT used
43 * in this calculation.
44 *
45 * This function assumes that the star's mean position is given as of J2000.
46 * At present, libnova does not support other epochs.
47 */
48 @nogc void ln_get_apparent_posn(const ref ln_equ_posn mean_position,
49 	const ref ln_equ_posn proper_motion, double JD, ref ln_equ_posn position) nothrow
50 {
51 	ln_equ_posn proper_position;
52 	ln_equ_posn aberration_position;
53 	ln_equ_posn precession_position;
54 
55 	ln_get_equ_pm(
56             mean_position, proper_motion, JD, proper_position);
57 	ln_get_equ_aber(proper_position, JD, aberration_position);
58 	ln_get_equ_prec(aberration_position, JD, precession_position);
59 	ln_get_equ_nut(precession_position, JD, position);
60 }
61 
62 }