Telescope tracking

Tools for supporting telescope tracking, with readily available position, rate of movement, and acceleration of the source's trajectory on sky. More...

Classes
struct	novas_observable
	Spherical and spectral coordinate set. More...
struct	novas_track
	The spherical and spectral tracking position of a source, and its first and second time derivatives. More...

Macros
#define	NOVAS_OBSERVABLE_INIT
	Empty initializer for novas_observable.
#define	NOVAS_TRACK_INIT
	Empty initializer for novas_track.

Typedefs
typedef struct novas_observable	novas_observable
	Spherical and spectral coordinate set.
typedef struct novas_track	novas_track
	The spherical and spectral tracking position of a source, and its first and second time derivatives.

Functions
int	novas_equ_track (const object *restrict source, const novas_frame *restrict frame, double dt, novas_track *restrict track)
	Calculates true-of-date equatorial tracking position and motion (first and second time derivatives) for the specified source in the given observing frame.
int	novas_hor_track (const object *restrict source, const novas_frame *restrict frame, RefractionModel ref_model, novas_track *restrict track)
	Calculates horizontal tracking position and motion (first and second time derivatives) for the specified source in the given observing frame.

Detailed Description

Tools for supporting telescope tracking, with readily available position, rate of movement, and acceleration of the source's trajectory on sky.

These parameters may be used directly for controlling telescope drive systems. Tracking parameters can be obtained for both equatorial and horizontal mounts. Apart from direct control of telescope drives, tracking information can also be used to calculate interpolated positions on sky on short timescales much faster than through full-fledged positional calculations.

Macro Definition Documentation

NOVAS_OBSERVABLE_INIT

#define NOVAS_OBSERVABLE_INIT

Empty initializer for novas_observable.

Since

1.3

See also

novas_observable

NOVAS_TRACK_INIT

#define NOVAS_TRACK_INIT

Empty initializer for novas_track.

Since

1.3

See also

novas_track

Typedef Documentation

novas_observable

typedef struct novas_observable novas_observable

Spherical and spectral coordinate set.

Since

1.3

Author

Attila Kovacs

See also

novas_track, NOVAS_OBSERVABLE_INIT

novas_track

typedef struct novas_track novas_track

The spherical and spectral tracking position of a source, and its first and second time derivatives.

As such, it may be useful for telescope drive control (position, velocity, and acceleration), or else for fast extrapolation of momentary positions without a full, and costly, recalculation of the positions at high rate over a suitable short period.

Since

1.3

Author

Attila Kovacs

See also

novas_hor_track(), novas_equ_track(), novas_track_pos(), NOVAS_TRACK_INIT

Function Documentation

novas_equ_track()

int novas_equ_track	(	const object *restrict	source,
		const novas_frame *restrict	frame,
		double	dt,
		novas_track *restrict	track )

Calculates true-of-date equatorial tracking position and motion (first and second time derivatives) for the specified source in the given observing frame.

The position and its derivatives are calculated via the more precise IAU2006 method, and CIRS.

Parameters

	Astronomical object of interest	Observed source
	Observing frames	Observing frame, defining the observer location and astronomical time of observation.
	dt	[s] Time step used for calculating derivatives.
[out]	track	Output tracking parameters to populate

Returns

0 if successful, or else -1 if any of the pointer arguments are NULL, or else an error code from novas_sky_pos().

Since

1.3

Author

Attila Kovacs

See also

novas_hor_track(), novas_track_pos()

References novas_sky_pos::dec, novas_sky_pos::dis, novas_timespec::fjd_tt, novas_make_frame(), novas_sky_pos(), NOVAS_TOD, novas_v2z(), novas_sky_pos::ra, novas_sky_pos::rv, and SKY_POS_INIT.

novas_hor_track()

int novas_hor_track	(	const object *restrict	source,
		const novas_frame *restrict	frame,
		RefractionModel	ref_model,
		novas_track *restrict	track )

Calculates horizontal tracking position and motion (first and second time derivatives) for the specified source in the given observing frame.

The position and its derivatives are calculated via the more precise IAU2006 method, and CIRS, and then converted to local horizontal coordinates using the specified refraction model (if any).

Parameters

	Astronomical object of interest	Observed source
	Observing frames	Observing frame, defining the observer location and astronomical time of observation.
	ref_model	Refraction model to use, or NULL for an unrefracted track.
[out]	track	Output tracking parameters to populate

Returns

0 if successful, or else -1 if any of the pointer arguments are NULL, or else an error code from novas_sky_pos(), or from novas_app_hor().

Since

1.3

Author

Attila Kovacs

See also

novas_equ_track(), novas_track_pos()

References novas_sky_pos::dec, novas_sky_pos::dis, novas_timespec::fjd_tt, ira_equinox(), NOVAS_AIRBORNE_OBSERVER, novas_app_to_hor(), NOVAS_CIRS, novas_make_frame(), NOVAS_OBSERVER_ON_EARTH, novas_sky_pos(), NOVAS_TOD, NOVAS_TRUE_EQUINOX, novas_v2z(), novas_sky_pos::ra, novas_sky_pos::rv, and SKY_POS_INIT.