libnova  v 0.16.0

Examples of how to use transformation functions.

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 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 2004 Liam Girdwood
#include <libnova/transform.h>
#include <libnova/julian_day.h>
#include <libnova/utility.h>
#include <stdio.h>
* Do some RA/DEC <--> ALT/AZ conversions for Alnilam
* in Leon (Spain) on 25/4/2004
int main (int argc, const char *argv[])
struct lnh_equ_posn hobject, hequ;
struct lnh_lnlat_posn hobserver;
struct ln_equ_posn object, equ;
struct ln_hrz_posn hrz;
struct lnh_hrz_posn hhrz;
struct ln_lnlat_posn observer;
struct ln_date date;
double JD;
* observers position
* longitude is measured positively eastwards
* i.e. Long 5d36m30W (Leon, Spain) = 354d24m30
* Lat for Leon = Lat 42d35m40 N
hobserver.lng.degrees = -5;
hobserver.lng.minutes = 36;
hobserver.lng.seconds = 30.0; = 42; = 35; = 40.0;
/* Alnilam */
hobject.ra.hours = 5;
hobject.ra.minutes = 36;
hobject.ra.seconds = 27.0;
hobject.dec.neg = 1;
hobject.dec.degrees = 1;
hobject.dec.minutes = 12;
hobject.dec.seconds = 0.0;
/* UT date and time */
date.years = 2004;
date.months = 4;
date.days = 25;
date.hours = 12;
date.minutes = 18;
date.seconds = 49.0;
JD = ln_get_julian_day(&date);
ln_hequ_to_equ(&hobject, &object);
ln_hlnlat_to_lnlat(&hobserver, &observer);
ln_get_hrz_from_equ(&object, &observer, JD, &hrz);
fprintf(stdout, "(Alnilam) Equ to Horiz ALT %f\n", hrz.alt);
fprintf(stdout, "(Alnilam) Equ to Horiz AZ %f\n",;
ln_hrz_to_hhrz(&hrz, &hhrz);
fprintf(stdout, "ALT %d:%d:%f AZ %d:%d:%f\n",
hhrz.alt.degrees, hhrz.alt.minutes, hhrz.alt.seconds,,,;
ln_get_equ_from_hrz (&hrz, &observer, JD, &equ);
fprintf(stdout, "(Alnilam) Horiz to Equ RA %f\n", equ.ra);
fprintf(stdout, "(Alnilam) Horiz to Equ DEC %f\n", equ.dec);
ln_equ_to_hequ(&equ, &hequ);
fprintf(stdout, "RA %d:%d:%f DEC %d:%d:%f\n",
hequ.ra.hours, hequ.ra.minutes, hequ.ra.seconds,
hequ.dec.degrees, hequ.dec.minutes, hequ.dec.seconds);
return 0;