libnova  v 0.16.0

Examples of how to use asteroid functions.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 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
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Copyright (C) 2003 Liam Girdwood <>
A simple example showing the asteroid Pallas.
#include <stdio.h>
#include <libnova/asteroid.h>
#include <libnova/julian_day.h>
#include <libnova/rise_set.h>
#include <libnova/transform.h>
#include <libnova/elliptic_motion.h>
/* just prints the date */
static void print_date(char *title, struct ln_zonedate *date)
fprintf(stdout, "\n%s\n",title);
fprintf(stdout, " Year : %d\n", date->years);
fprintf(stdout, " Month : %d\n", date->months);
fprintf(stdout, " Day : %d\n", date->days);
fprintf(stdout, " Hours : %d\n", date->hours);
fprintf(stdout, " Minutes : %d\n", date->minutes);
fprintf(stdout, " Seconds : %f\n", date->seconds);
int main(int argc, const char *argv[])
struct ln_rst_time rst;
struct ln_zonedate rise, set, transit;
struct ln_lnlat_posn observer;
struct ln_hrz_posn hrz;
struct ln_ell_orbit orbit;
struct ln_rect_posn posn;
double JD, M_JD;
double l,V,dist;
struct ln_equ_posn equ_posn;
double H, G;
double mag, elong, ph;
char *M_epoch = "K036A";
/* observers location (Edinburgh), used to calc rst */ = 55.92; /* 55.92 N */
observer.lng = -3.18; /* 3.18 W */
/* get Julian day from local time */
fprintf(stdout, "JD (sys) %f\n", JD);
/* Pallas orbital parameters
* Taken from MPCORB.DAT
* 00002 4.13 0.11 K036A 260.69458 310.45917 173.16479
* 34.84989 0.2299839 0.21343771 2.7730346 MPC 24084
* 5482 63 1839-1993 0.55 M-c 28 Bowell 0000 (2) Pallas
orbit.a = 2.7730346;
orbit.e = 0.2299839;
orbit.i = 34.84989; = 173.16479;
orbit.w = 310.45917;
orbit.n =0.21343771;
H = 4.13;
G = 0.11;
/* calc last passage in Perihelion, in julian day */
M_JD = ln_get_julian_from_mpc(M_epoch);
orbit.JD = ln_get_ell_last_perihelion (M_JD, 260.69458, orbit.n);
fprintf(stdout, "JD (Perihelion) %f\n", orbit.JD);
/* calc the earth centered position */
ln_get_ell_geo_rect_posn(&orbit, JD, &posn);
fprintf(stdout, "(Geocentric Rect Coords X) for Pallas %f\n", posn.X);
fprintf(stdout, "(Geocentric Rect Coords Y) for Pallas %f\n", posn.Y);
fprintf(stdout, "(Geocentric Rect Coords Z) for Pallas %f\n", posn.Z);
/* calc the sun centered position */
ln_get_ell_helio_rect_posn(&orbit, JD, &posn);
fprintf(stdout, "(Heliocentric Rect Coords X) for Pallas %f\n", posn.X);
fprintf(stdout, "(Heliocentric Rect Coords Y) for Pallas %f\n", posn.Y);
fprintf(stdout, "(Heliocentric Rect Coords Z) for Pallas %f\n", posn.Z);
/* get the RA and Dec */
ln_get_ell_body_equ_coords(JD, &orbit, &equ_posn);
fprintf(stdout, "(RA) for Pallas %f\n", equ_posn.ra);
fprintf(stdout, "(Dec) for Pallas %f\n", equ_posn.dec);
/* get Alt, Az */
ln_get_hrz_from_equ(&equ_posn, &observer, JD, &hrz);
fprintf(stdout, "Az %f\n",;
fprintf(stdout, "Alt %f\n", hrz.alt);
/* orbit length */
l = ln_get_ell_orbit_len(&orbit);
fprintf(stdout, "(Orbit Length) for Pallas in AU %f\n", l);
/* orbit velocities */
V = ln_get_ell_orbit_pvel(&orbit);
fprintf(stdout, "(Orbit Perihelion Vel) for Pallas in kms %f\n", V);
V = ln_get_ell_orbit_avel(&orbit);
fprintf(stdout, "(Orbit Aphelion Vel) for Pallas in kms %f\n", V);
V = ln_get_ell_orbit_vel(JD, &orbit);
fprintf(stdout, "(Orbit Vel JD) for Pallas in kms %f\n", V);
/* earth and solar distance */
dist = ln_get_ell_body_solar_dist(JD, &orbit);
fprintf(stdout, "Solar Dist (AU) : %f\n", dist);
dist = ln_get_ell_body_earth_dist(JD, &orbit);
fprintf(stdout, "Earth Dist (AU) : %f\n", dist);
/* phase angle, elongation */
ph = ln_get_ell_body_phase_angle(JD, &orbit);
fprintf(stdout, "Phase angle : %f\n",ph);
elong = ln_get_ell_body_elong(JD, &orbit);
fprintf(stdout, "Elongation : %f\n",elong);
/* magnitude */
mag = ln_get_asteroid_mag(JD, &orbit, H, G);
fprintf(stdout, "Magnitude : %f\n", mag);
/* rise, set and transit time */
if (ln_get_ell_body_rst(JD, &observer, &orbit, &rst) != 0)
fprintf(stdout, "Pallas is circumpolar\n");
else {
ln_get_local_date(rst.rise, &rise);
ln_get_local_date(rst.transit, &transit);
ln_get_local_date(rst.set, &set);
print_date("Rise", &rise);
print_date("Transit", &transit);
print_date("Set", &set);
return 0;