asteroid.c

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
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 
Copyright (C) 2003 Liam Girdwood <lgirdwood@gmail.com>
 
 
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 */
    observer.lat = 55.92; /* 55.92 N */
    observer.lng = -3.18; /* 3.18 W */
    
    /* get Julian day from local time */
    JD = ln_get_julian_from_sys();  
    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;
    orbit.omega =  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",hrz.az);
    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;
}