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/*****************************************************************************/
/* easpec.h */
/*****************************************************************************/
#ifndef __EASPEC_H_INCLUDED
#define __EASPEC_H_INCLUDED 1
/* get_observer_coords():
Calculates the geocentric equatorial Cartesian coordiantes of the observer
located at (lon,lat) at the time instance 'jdate'. */
void get_observer_coords(double jdate,double lon,double lat,
double *x,double *y,double *z);
/* get_sideral_time():
Calculates and returns the sideral time in Greenwih at the instance 'jdate'*/
double get_sideral_time(double jdate);
/* get_earth_axis_angle():
Calculates and returns the deviation angle of the rotational axis of the
Earth to the norm of the ecliptical plane at the given instance 'jdate'.
(Note that this is a non-covariant quantity, so this function might be
replaced or changed in future releases of this library...) */
double get_earth_axis_angle(double jdate);
/* get_heiocentric_julian_date():
Calculates the heliocentric (not barycentric!) correction for the
time instance 'jdate' at the spherical equatorial point ('ra', 'dec').
The corrected time instance is returned. */
double get_heliocentric_julian_date(double jdate,double ra,double dec);
/* get_heiocentric_julian_date_diff():
Calculates the heliocentric (not barycentric!) difference for the
time instance 'jdate' at the spherical equatorial point ('ra', 'dec').
The difference HJD-JD is returned. */
double get_heliocentric_julian_date_diff(double jdate,double ra,double dec);
/* get_heiocentric_julian_date_epoch():
Same as get_heiocentric_julian_date(), but the coordinates 'ra' and 'dec'
are for the epoch (in Julian years) 'epoch'. */
double get_heliocentric_julian_date_epoch(double jdate,double ra,double dec,double y0);
/* get_barycentric_julian_date():
Calculates the barycentric correction for the time instance 'jdate' at the
spherical equatorial point ('ra', 'dec'). The corrected time instance is
returned. */
double get_barycentric_julian_date(double jdate,double ra,double dec);
/* get_barycentric_julian_date_diff():
Calculates the barycentric correction for the time instance 'jdate' at the
spherical equatorial point ('ra', 'dec'). The difference BJD-JD is
returned. */
double get_barycentric_julian_date_diff(double jdate,double ra,double dec);
/* get_annular_parallax_correction():
This function calculates the annular parallax correction (i.e. as it
would observed from the Sun), for the celestial object located at
(ra,dec) (RA, DEC, in degrees) within a distance of 'dis' parsec at
the instance 'jdate' (JD). The corrected coordinates are stored in 'rra'
and 'rdec'. */
int get_annular_parallax_correction(double jdate,double ra,double dec,
double dis,double *rra,double *rdec);
#endif
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