topocentric.c File Reference

Reduce from geocentric to topocentric coordinates. More...

#include <math.h>
#include <stdlib.h>
#include "aephem.h"

Functions
void	ae_topocentric (double jd_tt, double jd_ut1, double tlat, double glat, double tlong, double trho, double(*refrac)(double, void *), void *refrac_param, double dist, double *ra, double *dec)
	Apply diurnal aberrations and calculate topocentric altitude and azimuth. More...
void	aes_topocentric (double jd_ut1, double glat, double tlong, double dist, double *ra, double *dec)
	Apply diurnal aberrations and calculate topocentric altitude and azimuth. More...

Detailed Description

Reduce from geocentric to topocentric coordinates.

Function Documentation

void ae_topocentric	(	double	jd_tt,
		double	jd_ut1,
		double	tlat,
		double	glat,
		double	tlong,
		double	trho,
		double(*)(double, void *)	refrac,
		void *	refrac_param,
		double	dist,
		double *	ra,
		double *	dec
	)

Apply diurnal aberrations and calculate topocentric altitude and azimuth.

Apply diurnal aberrations and calculate topocentric altitude and azimuth, given the geocentric apparent right ascension and declination. From AA page B60 and D3.

The geocentric coordinates can be obtained from ae_geocentric_from_orbit() or a similar routine.

Parameters

jd_tt	The Julian date in TT.
jd_ut1	The Julian date in UT1 measure.
tlat	The geocentric latitude of the observer, in degrees.
glat	The geodetic latitude of the observer, in degrees.
tlong	The longitude of the observer, in degrees.
trho	The distance from the centre of the earth to the observer, in earth radii.
refrac	A routine that calculates refraction (pass NULL to perform no refraction correction). Its first argument is the altitude, in degrees. Its second argument is a void pointer for passing other parameters, which will be particular to the refraction algorithm. These parameters are passed via refrac_param.
refrac_param	For passing auxiliary parameters to the refrac function. Pass NULL if refrac is not being used.
dist	The geocentric distance to the object being observed, in AU. Pass 0 for extra-solar-system objects.
ra	The right ascension of the object, in degrees; this routine returns the topocentric right ascension in this parameter.
dec	The declination of the object, in degrees; this routine returns the topocentric declination in this parameter.

References AE_ADD_ABERRATION, ae_altaz_to_radec(), ae_diurnal_aberration(), ae_diurnal_parallax(), ae_epsilon(), ae_last(), ae_nutation_lon_ob(), and ae_radec_to_altaz().

Referenced by aes_topocentric().

void aes_topocentric	(	double	jd_ut1,
		double	glat,
		double	tlong,
		double	dist,
		double *	ra,
		double *	dec
	)

Apply diurnal aberrations and calculate topocentric altitude and azimuth.

This is a simplified version of ae_topocentric(), which automatically calculates jd_tt, tlat and trho. It assumes that the altitude of the observer is at sea level. It also uses no atmospheric model. It might be less efficient to use this routine if speed is required.

Parameters

jd_ut1	The Julian date in UT1 measure.
glat	The geodetic latitude of the observer, in degrees.
tlong	The longitude of the observer, in degrees.
dist	The geocentric distance to the object being observed, in AU. Pass 0 for extra-solar-system objects.
ra	The right ascension of the object, in degrees; this routine returns the topocentric right ascension in this parameter.
dec	The declination of the object, in degrees; this routine returns the topocentric declination in this parameter.

References ae_delta_t(), ae_geocentric_lat(), AE_S_PER_D, and ae_topocentric().