target.c File Reference

Macros
#define	_GNU_SOURCE
	for strcasecmp()

Functions
short	make_cat_entry (const char *restrict name, const char *restrict catalog, long cat_num, double ra, double dec, double pm_ra, double pm_dec, double parallax, double rad_vel, cat_entry *source)
int	make_cat_object (const cat_entry *star, object *source)
int	make_cat_object_sys (const cat_entry *star, const char *restrict system, object *source)
int	make_ephem_object (const char *name, long num, object *body)
short	make_object (enum novas_object_type type, long number, const char *name, const cat_entry *star, object *source)
int	make_orbital_object (const char *name, long num, const novas_orbital *orbit, object *body)
int	make_planet (enum novas_planet num, object *restrict planet)
int	make_redshifted_cat_entry (const char *name, double ra, double dec, double z, cat_entry *source)
int	make_redshifted_object (const char *name, double ra, double dec, double z, object *source)
int	make_redshifted_object_sys (const char *name, double ra, double dec, const char *restrict system, double z, object *source)
void	novas_case_sensitive (int value)
double	novas_helio_dist (double jd_tdb, const object *restrict source, double *restrict rate)
int	novas_init_cat_entry (cat_entry *restrict source, const char *restrict name, double ra, double dec)
enum novas_planet	novas_planet_for_name (const char *restrict name)
int	novas_set_catalog (cat_entry *restrict source, const char *restrict catalog, long num)
int	novas_set_distance (cat_entry *source, double parsecs)
int	novas_set_lsr_vel (cat_entry *source, double epoch, double v_kms)
int	novas_set_parallax (cat_entry *source, double mas)
int	novas_set_proper_motion (cat_entry *source, double pm_ra, double pm_dec)
int	novas_set_redshift (cat_entry *source, double z)
int	novas_set_ssb_vel (cat_entry *source, double v_kms)
double	novas_solar_power (double jd_tdb, const object *restrict source)
int	proper_motion (double jd_tdb_in, const double *pos, const double *restrict vel, double jd_tdb_out, double *out)
int	starvectors (const cat_entry *restrict star, double *restrict pos, double *restrict motion)
short	transform_cat (enum novas_transform_type option, double jd_tt_in, const cat_entry *in, double jd_tt_out, const char *out_id, cat_entry *out)
int	transform_hip (const cat_entry *hipparcos, cat_entry *hip_2000)

Detailed Description

Date

Created on Mar 6, 2025

Author

G. Kaplan and Attila Kovacs

Functions that define an observing target.

Function Documentation

make_cat_entry()

short make_cat_entry	(	const char *restrict	name,
		const char *restrict	catalog,
		long	cat_num,
		double	ra,
		double	dec,
		double	pm_ra,
		double	pm_dec,
		double	parallax,
		double	rad_vel,
		cat_entry *	source )

Fully populates the data structure for a catalog source, such as a star, with all parameters provided at once.

Alternatively, you may use novas_init_cat_entry() to initialize just with the name and R.A./Dec coordinates, and then add further information step-by-step as needed, icluding using alternative parameters (SSB vs. LSR velocity, vs. redshift; parallax vs. distance). The latter approach provides more flexibility, and will result in more readable code, which is also easier to debug.

Parameters

	name	Object name (less than SIZE_OF_OBJ_NAME in length). It may be NULL if not relevant.
	catalog	Catalog identifier or epoch (less than SIZE_OF_CAT_NAME in length). E.g. 'HIP' for Hipparcos, 'TY2' for Tycho-2; or 'ICRS', 'B1950', 'J2000'. It may be NULL if not relevant.
	cat_num	Object number in the catalog. It is not used internally, so you may set it to anything that is meaningful to you, or set it to 0 as a default.
	ra	[h] Right ascension of the object.
	dec	[deg] Declination of the object.
	pm_ra	[mas/yr] Proper motion in right ascension.
	pm_dec	[mas/yr] Proper motion in declination.
	parallax	[mas] Parallax.
	rad_vel	[km/s] Radial velocity relative to the Solar-System Barycenter (SSB). To convert velocities defined against the Local Standard of Rest (LSR), you may use novas_lsr_to_ssb_vel() to convert appropriately. Or, to convert from a redshift value, you might use novas_z2v().
[out]	source	Pointer to data structure to populate.

Returns

0 if successful, or -1 if the output argument is NULL, 1 if the 'star_name' is too long or 2 if the 'catalog' name is too long.

See also

novas_init_cat_entry()

novas_lsr_to_ssb_vel()

make_redshifted_cat_entry()

make_cat_object_sys()

transform_cat()

References novas_init_cat_entry(), novas_set_catalog(), novas_set_parallax(), novas_set_proper_motion(), novas_set_ssb_vel(), and rad_vel().

make_cat_object()

int make_cat_object	(	const cat_entry *	star,
		object *	source )

Populates and object data structure with the data for a catalog source. The astrometric parameters must be defined with ICRS. To create objects in other reference systems, use make_cat_object_sys() instead.

Parameters

	star	Pointer to structure to populate with the catalog data for a celestial object located outside the solar system, specified with ICRS astrometric parameters.
[out]	source	Pointer to the celestial object data structure to be populated.

Returns

0 if successful, or -1 if either argument is NULL, or else 5 if 'name' is too long.

See also

make_cat_object_sys()

novas_init_cat_entry()

make_cat_entry()

make_planet()

make_ephem_object()

novas_geom_posvel()

place()

Since

1.1

Author

Attila Kovacs

References make_object(), NOVAS_CATALOG_OBJECT, cat_entry::starname, and cat_entry::starnumber.

make_cat_object_sys()

int make_cat_object_sys	(	const cat_entry *	star,
		const char *restrict	system,
		object *	source )

Populates and object data structure with the data for a catalog source for a given system of catalog coordinates.

Parameters

	star	Pointer to structure to populate with the catalog data for a celestial object located outside the solar system.
	system	Input catalog coordinate system epoch, e.g. "ICRS", "B1950.0", "J2000.0", "FK4", "FK5", or "HIP". In general, any Besselian or Julian year epoch can be used by year (e.g. "B1933.193" or "J2022.033"), or else the fixed value listed. If 'B' or 'J' is ommitted in front of the epoch year, then Besselian epochs are assumed prior to 1984.0. (See ‘novas_epoch() for more).
[out]	source	Pointer to the celestial object data structure to be populated with the corresponding ICRS catalog coordinates, after appying proper-motion and precession corrections as appropriate.

Returns

0 if successful, or -1 if any argument is NULL or if the input 'system’ is invalid, or else 5 if 'name' is too long.

See also

make_cat_object()

make_redshifted_object_sys()

novas_epoch()

make_cat_entry()

place()

NOVAS_SYSTEM_ICRS

NOVAS_SYSTEM_HIP

NOVAS_SYSTEM_J2000

NOVAS_SYSTEM_B1950

Since

1.3

Author

Attila Kovacs

References make_cat_object(), and object::star.

make_ephem_object()

int make_ephem_object	(	const char *	name,
		long	num,
		object *	body )

Sets a celestial object to be a Solar-system ephemeris body. Typically this would be used to define minor planets, asteroids, comets and planetary satellites.

Parameters

	name	Name of object. By default converted to upper-case, unless novas_case_sensitive() was called with a non-zero argument. Max. SIZE_OF_OBJ_NAME long, including termination. If the ephemeris provider uses names, then the name should match those of the ephemeris provider – otherwise it is not important.
	num	Solar-system body ID number (e.g. NAIF). The number should match the needs of the ephemeris provider used with NOVAS. (If the ephemeris provider is by name and not ID number, then the number here is not important).
[out]	body	Pointer to structure to populate.

Returns

0 if successful, or else -1 if the 'body' pointer is NULL or the name is too long.

See also

set_ephem_provider()

make_planet()

make_cat_entry()

novas_geom_posvel()

place()

Since

1.0

Author

Attila Kovacs

References make_object(), and NOVAS_EPHEM_OBJECT.

make_object()

short make_object	(	enum novas_object_type	type,
		long	number,
		const char *	name,
		const cat_entry *	star,
		object *	source )

Deprecated

More functionality and more readable, code results from using one of the specific alternatives: make_cat_object(), make_redshifted_object(), make_planet(), make_ephem_object(), or make_orbital_object().

Populates an object data structure using the parameters provided. By default (for compatibility with NOVAS C) source names are converted to upper-case internally. You can however enable case-sensitive processing by calling novas_case_sensitive() before.

NOTES:

1. This call does not initialize the orbit field (added in v1.2) with zeroes to remain ABI compatible with versions <1.2.

Parameters

	type	The type of object. NOVAS_PLANET (0), NOVAS_EPHEM_OBJECT (1) or NOVAS_CATALOG_OBJECT (2), or NOVAS_ORBITAL_OBJECT (3).
	number	The novas ID number (for solar-system bodies only, otherwise ignored)
	name	The name of the object (case insensitive). It should be shorter than SIZE_OF_OBJ_NAME or else an error will be returned. The name is converted to upper internally unless novas_case_sensitive() was called before to change that.
	star	Pointer to structure to populate with the catalog data for a celestial object located outside the solar system. Used only if type is NOVAS_CATALOG_OBJECT, otherwise ignored and can be NULL.
[out]	source	Pointer to the celestial object data structure to be populated.

Returns

0 if successful, or -1 if 'cel_obj' is NULL or when type is NOVAS_CATALOG_OBJECT and 'star' is NULL, or else 1 if 'type' is invalid, 2 if 'number' is out of legal range or 5 if 'name' is too long.

See also

novas_case_sensitive()

make_cat_object()

make_redshifted_object()

make_planet()

make_ephem_object()

make_orbital_object()

novas_geom_posvel()

place()

References object::name, NOVAS_CATALOG_OBJECT, NOVAS_OBJECT_TYPES, NOVAS_PLANET, NOVAS_PLANETS, object::number, object::star, and object::type.

make_orbital_object()

int make_orbital_object	(	const char *	name,
		long	num,
		const novas_orbital *	orbit,
		object *	body )

Sets a celestial object to be a Solar-system orbital body. Typically this would be used to define minor planets, asteroids, comets, or even planetary satellites.

Parameters

	name	Name of object. It may be NULL if not relevant.
	num	Solar-system body ID number (e.g. NAIF). It is not required and can be set e.g. to -1 if not relevant to the caller.
	orbit	The orbital parameters to adopt. The data will be copied, not referenced.
[out]	body	Pointer to structure to populate.

Returns

0 if successful, or else -1 if the 'orbit' or 'body' pointer is NULL or the name is too long.

See also

novas_orbit_posvel()

make_planet()

make_ephem_object()

novas_geom_posvel()

place()

Since

1.2

Author

Attila Kovacs

References make_object(), NOVAS_ORBITAL_OBJECT, and object::orbit.

make_planet()

int make_planet	(	enum novas_planet	num,
		object *restrict	planet )

Sets a celestial object to be a major planet, or the Sun, Moon, Solar-system Barycenter, etc.

Parameters

	num	Planet ID number (NOVAS convention)
[out]	planet	Pointer to structure to populate.

Returns

0 if successful, or else -1 if the 'planet' pointer is NULL.

See also

make_ephem_object()

make_cat_entry()

place()

Since

1.0

Author

Attila Kovacs

References make_object(), NOVAS_PLANET, NOVAS_PLANET_NAMES_INIT, and NOVAS_PLANETS.

make_redshifted_cat_entry()

int make_redshifted_cat_entry	(	const char *	name,
		double	ra,
		double	dec,
		double	z,
		cat_entry *	source )

Populates a celestial object data structure with the parameters for a redhifted catalog source, such as a distant quasar or galaxy. It is similar to make_cat_object() except that it takes a Doppler-shift (z) instead of radial velocity and it assumes no parallax and no proper motion (appropriately for a distant redshifted source). The catalog name is set to EXT to indicate an extragalactic source, and the catalog number defaults to 0. The user may change these default field values as appropriate afterwards, if necessary.

Parameters

	name	Object name (less than SIZE_OF_OBJ_NAME in length). It may be NULL.
	ra	[h] Right ascension of the object (hours).
	dec	[deg] Declination of the object (degrees).
	z	Redhift value (λobs / λrest - 1 = frest / fobs - 1).
[out]	source	Pointer to structure to populate.

Returns

0 if successful, or 5 if 'name' is too long, else -1 if the 'source' pointer is NULL.

See also

make_redshifted_object_sys()

novas_set_cat_info()

novas_v2z()

Since

1.2

Author

Attila Kovacs

References novas_init_cat_entry(), novas_set_catalog(), and novas_set_redshift().

make_redshifted_object()

int make_redshifted_object	(	const char *	name,
		double	ra,
		double	dec,
		double	z,
		object *	source )

Populates a celestial object data structure with the ICRS astrometric parameters for a redhifted catalog source, such as a distant quasar or galaxy. To create redshifted objects with in other reference systems, use make_redshifted_object_sys() instead.

It is similar to make_cat_object() except that it takes a Doppler-shift (z) instead of radial velocity and it assumes no parallax and no proper motion (appropriately for a distant redshifted source). The catalog name is set to EXT to indicate an extragalactic source, and the catalog number defaults to 0. The user may change these default field values as appropriate afterwards, if necessary.

Parameters

	name	Object name (less than SIZE_OF_OBJ_NAME in length). It may be NULL.
	ra	[h] ICRS Right ascension of the object (hours).
	dec	[deg] ICRS Declination of the object (degrees).
	z	Redhift value (λobs / λrest - 1 = frest / fobs - 1).
[out]	source	Pointer to structure to populate.

Returns

0 if successful, or 5 if 'name' is too long, else -1 if the 'source' pointer is NULL.

See also

make_redshifted_object_sys()

make_cat_object()

novas_v2z()

Since

1.2

Author

Attila Kovacs

References make_cat_object(), and make_redshifted_cat_entry().

make_redshifted_object_sys()

int make_redshifted_object_sys	(	const char *	name,
		double	ra,
		double	dec,
		const char *restrict	system,
		double	z,
		object *	source )

Populates a celestial object data structure with the parameters for a redhifted catalog source, such as a distant quasar or galaxy, for a given system of catalog coordinates.

Parameters

	name	Object name (less than SIZE_OF_OBJ_NAME in length). It may be NULL.
	ra	[h] ICRS Right ascension of the object (hours).
	dec	[deg] ICRS Declination of the object (degrees).
	system	Input catalog coordinate system epoch, e.g. "ICRS", "B1950.0", "J2000.0", "FK4", "FK5", or "HIP". In general, any Besselian or Julian year epoch can be used by year (e.g. "B1933.193" or "J2022.033"), or else the fixed value listed. If 'B' or 'J' is ommitted in front of the epoch year, then Besselian epochs are assumed prior to 1984.0.
	z	Redhift value (λobs / λrest - 1 = frest / fobs - 1).
[out]	source	Pointer to the celestial object data structure to be populated with the corresponding ICRS catalog coordinates.

Returns

0 if successful, or -1 if any of the pointer arguments is NULL or the 'system' is invalid, or else 1 if 'type' is invalid, 2 if 'number' is out of legal range or 5 if 'name' is too long.

See also

make_redshifted_object()

make_cat_object_sys()

novas_epoch()

place()

NOVAS_SYSTEM_ICRS

NOVAS_SYSTEM_HIP

NOVAS_SYSTEM_J2000

NOVAS_SYSTEM_B1950

Since

1.3

Author

Attila Kovacs

References make_redshifted_object(), and object::star.

novas_case_sensitive()

void novas_case_sensitive

(

int

value

)

Enables or disables case-sensitive processing of the object name. The effect is not retroactive. The setting will only affect the celestial objects that are defined after the call. Note, that catalog names, set via make_cat_entry() are always case sensitive regardless of this setting.

Parameters

value

(boolean) TRUE (non-zero) to enable case-sensitive object names, or else FALSE (0) to convert names to upper case only (NOVAS C compatible behavior).

See also

make_object()

Since

1.0

Author

Attila Kovacs

novas_helio_dist()

double novas_helio_dist	(	double	jd_tdb,
		const object *restrict	source,
		double *restrict	rate )

Returns a Solar-system body's distance from the Sun, and optionally also the rate of recession. It may be useful, e.g. to calculate the body's heating from the Sun.

Parameters

	jd_tdb	[day] Barycentric Dynamical Time (TDB) based Julian date. You may want to use a time that is antedated to when the observed light originated from the source.
	source	Observed Solar-system source
[out]	rate	[AU/day] (optional) Returned rate of recession from Sun

Returns

[AU] Distance from the Sun, or NAN if not a Solar-system source.

Since

1.3

Author

Attila Kovacs

See also

novas_solar_power()

novas_solar_illum()

References ephemeris(), NOVAS_CATALOG_OBJECT, NOVAS_HELIOCENTER, NOVAS_REDUCED_ACCURACY, and novas_vlen().

novas_init_cat_entry()

int novas_init_cat_entry	(	cat_entry *restrict	source,
		const char *restrict	name,
		double	ra,
		double	dec )

Initializes a catalog entry, such as a star or a distant galaxy, with a name and coordinates. All other fields of the cat_entry structure will be initialized with zeroes. After the initialization, you may set further properties, such as:

• a radial velocity, LSR velocity, or redshift.
• a parallax or distance
• proper motion
• optional catalog name an number

The typical process for setting up a catalog source is captured by the following steps:

1. Initialize the cat_entry with source name and RA / Dec coordinates using novas_init_cat_entry().
2. (optional) Set radial velocity, as needed, via either:
   • radial velocity (km/s) w.r.t SSB using novas_set_ssb_vel(), or
   • LSR velocity (km/s) using novas_set_lsr_vel(), or
   • redshift using novas_set_redshift().
3. (optional) Set proper motions (mas/yr), as needed, using novas_set_proper_motion().
4. (optional) Set parallax, as needed, via either:
   • parallax (mas) using novas_set_parallax(), or
   • distance (parcsec) using novas_set_distance().
5. (optional) Assign catalog info if desired via novas_set_catalog().

After the initialization (Step 1), order does not matter.

Parameters

[out]	source	Output structure to populate.
	name	Object name (less than SIZE_OF_OBJ_NAME in length). It may be NULL if not relevant.
	ra	[h] Right ascension of the object.
	dec	[deg] Declination of the object.

Returns

0 if successful, or else -1 in the source is NULL (errno set to EINVAL) or 1 if the name is too long (errno is set to ERANGE).

Since

1.5

Author

Attila Kovacs

See also

novas_set_ssb_vel()

novas_set_lsr_vel()

novas_set_redshift()

novas_set_proper_motion()

novas_set_parallax()

novas_set_distance()

novas_set_cat_info()

novas_make_cat_entry()

References SIZE_OF_OBJ_NAME.

novas_planet_for_name()

enum novas_planet novas_planet_for_name

(

const char *restrict

name

)

Returns the NOVAS planet ID for a given name (case insensitive), or -1 if no match is found.

Parameters

name	The planet name, or that for the "Sun", "Moon" or "SSB" (case insensitive). The spelled out "Solar System Barycenter" is also recognized with either spaces, hyphens ('-') or underscores ('_') separating the case insensitive words.

Returns

The NOVAS major planet ID, or -1 (errno set to EINVAL) if the input name is NULL or if there is no match for the name provided.

Author

Attila Kovacs

Since

1.2

See also

make_planet()

References NOVAS_PLANET_NAMES_INIT, NOVAS_PLANETS, and NOVAS_SSB.

novas_set_catalog()

int novas_set_catalog	(	cat_entry *restrict	source,
		const char *restrict	catalog,
		long	num )

Sets the optional catalog information for a sidereal source. SuperNOVAS does not use the catalog information internally. It is entirely for the convenience of the user to set these values if it is useful to them.

Parameters

[out]	source	Output structure to populate with the parameters.
	catalog	Catalog identifier or epoch (less than SIZE_OF_CAT_NAME in length). E.g. 'HIP' for Hipparcos, 'TY2' for Tycho-2; or 'ICRS', 'B1950', 'J2000'. It may be NULL if not relevant.
	num	Object's number in catalog.

Returns

0 if successful, or else -1 in the source is NULL (errno set to EINVAL), or 2 if the catalog name is too long (errno is set to ERANGE).

Since

1.5

Author

Attila Kovacs

See also

novas_init_cat_entry()

References SIZE_OF_CAT_NAME.

novas_set_distance()

int novas_set_distance	(	cat_entry *	source,
		double	parsecs )

Sets the distance for a catalog source.

Parameters

[out]	source	Output structure to populate with the parameters.
	parsecs	[pc] distance

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL).

Since

1.5

Author

Attila Kovacs

See also

novas_set_distance()

novas_init_cat_entry()

References novas_set_parallax().

novas_set_lsr_vel()

int novas_set_lsr_vel	(	cat_entry *	source,
		double	epoch,
		double	v_kms )

Sets a radial velocity for a catalog source, defined w.r.t. the Local Standard of Rest (LSR).

Parameters

[out]	source	Output structure to populate with the parameters.
	v_kms	[km/s] Radial velocity of source w.r.t. the Local Standard of Rest (LSR).
	epoch	[yr] Coordinate epoch.

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL) or if the velocity exceeds the speed of light (errno set to ERANGE).

Since

1.5

Author

Attila Kovacs

See also

novas_set_ssb_vel()

novas_lsr_to_ssb_vel()

novas_set_redshift()

novas_init_cat_entry()

References cat_entry::dec, novas_lsr_to_ssb_vel(), novas_set_ssb_vel(), and cat_entry::ra.

novas_set_parallax()

int novas_set_parallax	(	cat_entry *	source,
		double	mas )

Sets the parallax (a measure of distance) for a catalog source.

Parameters

[out]	source	Output structure to populate with the parameters.
	mas	[mas] Parallax

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL).

Since

1.5

Author

Attila Kovacs

See also

novas_set_distance()

novas_init_cat_entry()

References cat_entry::parallax.

novas_set_proper_motion()

int novas_set_proper_motion	(	cat_entry *	source,
		double	pm_ra,
		double	pm_dec )

Sets the proper-motion for a (Galactic) catalog source.

Parameters

[out]	source	Output structure to populate with the parameters.
	pm_ra	[mas/yr] Proper motion in right ascension.
	pm_dec	[mas/yr] Proper motion in declination.

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL).

Since

1.5

Author

Attila Kovacs

See also

novas_set_parallax()

novas_set_distance()

novas_init_cat_entry()

References cat_entry::promodec, and cat_entry::promora.

novas_set_redshift()

int novas_set_redshift	(	cat_entry *	source,
		double	z )

Sets a redhift for a catalog source, as a relativistic measure of velocity.

Parameters

[out]	source	Output structure to populate with the parameters.
	z	[-1:inf] The redshift measure z, defined as (1 + z) = sqrt((1 + v/_c_) / (1 - v/_c_))

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL) or if the redshift is invalid (errno set to ERANGE).

Since

1.5

Author

Attila Kovacs

See also

novas_set_ssb_vel()

novas_init_cat_entry()

References novas_set_ssb_vel(), and novas_z2v().

novas_set_ssb_vel()

int novas_set_ssb_vel	(	cat_entry *	source,
		double	v_kms )

Sets a radial velocity for a catalog source, defined w.r.t. the Solar-System Barycenter (SSB).

Parameters

[out]	source	Output structure to populate with the parameters.
	v_kms	[km/s] Radial velocity of source w.r.t. the Solar-System Barycenter (SSB).

Returns

0 if successful, or else -1 in the source is NULL (errno is set to EINVAL) or if the velocity exceeds the speed of light (errno set to ERANGE).

Since

1.5

Author

Attila Kovacs

See also

novas_set_lsr_vel()

novas_set_redshift()

novas_init_cat_entry()

References NOVAS_C, and cat_entry::radialvelocity.

novas_solar_power()

double novas_solar_power	(	double	jd_tdb,
		const object *restrict	source )

Returns the typical incident Solar power on a Solar-system body at the time of observation.

Parameters

jd_tdb	[day] Barycentric Dynamical Time (TDB) based Julian date. You may want to use a time that is antedated to when the observed light originated ( was reflected) from the source.
source	Observed Solar-system source

Returns

[W/m²] Incident Solar power on the illuminated side of the object, or NAN if not a Solar-system source or if the source is the Sun itself.

Since

1.3

Author

Attila Kovacs

See also

novas_solar_illum()

References novas_helio_dist(), and NOVAS_SOLAR_CONSTANT.

proper_motion()

int proper_motion	(	double	jd_tdb_in,
		const double *	pos,
		const double *restrict	vel,
		double	jd_tdb_out,
		double *	out )

Applies proper motion, including foreshortening effects, to a star's position.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.

Parameters

	jd_tdb_in	[day] Barycentric Dynamical Time (TDB) based Julian date of the first epoch.
	pos	[AU] Position vector at first epoch.
	vel	[AU/day] Velocity vector at first epoch.
	jd_tdb_out	[day] Barycentric Dynamical Time (TDB) based Julian date of the second epoch.
[out]	out	Position vector at second epoch. It can be the same vector as the input.

Returns

0 if successful, or -1 if any of the vector areguments is NULL.

See also

transform_cat()

starvectors()

int starvectors	(	const cat_entry *restrict	star,
		double *restrict	pos,
		double *restrict	motion )

Converts angular quantities for stars to vectors.

NOTES:

1. The velocity returned should not be used for deriving spectroscopic radial velocity. It is a measure of the perceived change of the stars position, not a true physical velocity.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.

Parameters

	star	Pointer to catalog entry structure containing ICRS catalog
[out]	pos	[AU] Position vector, equatorial rectangular coordinates, It may be NULL if not required.
[out]	motion	[AU/day] Perceived motion of star, in equatorial rectangular coordinates. It must be distinct from the pos output vector, and may be NULL if not required. Note, that it is suitable only for calculating the apparent 3D location of the star at a different time, and should not be used as a measure of physical velocity, e.g. for spectroscopic radial velocity determination.

Returns

0 if successful, or -1 if the star argument is NULL or the output vectors are the same pointer.

See also

make_cat_entry()

novas_init_cat_entry()

References NOVAS_KMS, novas_los_to_xyz(), and radec2vector().

transform_cat()

short transform_cat	(	enum novas_transform_type	option,
		double	jd_tt_in,
		const cat_entry *	in,
		double	jd_tt_out,
		const char *	out_id,
		cat_entry *	out )

Transform a star's catalog quantities for a change the coordinate system and/or the date for which the positions are calculated. Also used to rotate catalog quantities on the dynamical equator and equinox of J2000.0 to the ICRS or vice versa.

'date_incat' and 'date_newcat' may be specified either as a Julian date (e.g., 2433282.5 or NOVAS_JD_B1950) or a fractional Julian year and fraction (e.g., 1950.0). Values less than 10000 are assumed to be years. You can also use the supplied constants NOVAS_JD_J2000 or NOVAS_JD_B1950. The date arguments are ignored for the ICRS frame conversion options.

If 'option' is PROPER_MOTION (1), input data can be in any reference system. If 'option' is PRECESSION (2) or CHANGE_EPOCH (3), input data is assume to be in the dynamical system of 'date_incat' and produces output in the dynamical system of 'date_outcat'. If 'option' is CHANGE_J2000_TO_ICRS (4), the input data should be in the J2000.0 dynamical frame. And if 'option' is CHANGE_ICRS_TO_J2000 (5), the input data must be in the ICRS, and the output will be in the J2000 dynamical frame.

This function cannot be properly used to bring data from old star catalogs into the modern system, because old catalogs were compiled using a set of constants that are incompatible with modern values. In particular, it should not be used for catalogs whose positions and proper motions were derived by assuming a precession constant significantly different from the value implicit in function precession().

Parameters

	option	Type of transformation
	jd_tt_in	[day|yr] Terrestrial Time (TT) based Julian date, or year, of input catalog data. Not used if option is CHANGE_J2000_TO_ICRS (4) or CHANGE_ICRS_TO_J2000 (5).
	in	An entry from the input catalog, with units as given in the struct definition
	jd_tt_out	[day|yr] Terrestrial Time (TT) based Julian date, or year, of output catalog data. Not used if option is CHANGE_J2000_TO_ICRS (4) or CHANGE_ICRS_TO_J2000 (5).
	out_id	Catalog identifier (0 terminated). It may also be NULL in which case the catalog name is inherited from the input.
[out]	out	The transformed catalog entry, with units as given in the struct definition. It may be the same as the input.

Returns

0 if successful, -1 if either vector argument is NULL or if the 'option' is invalid, or else 2 if 'out_id' is too long.

See also

transform_hip()

make_cat_entry()

novas_epoch()

NOVAS_JD_J2000

NOVAS_JD_B1950

NOVAS_JD_HIP

References cat_entry::catalog, CHANGE_EPOCH, CHANGE_ICRS_TO_J2000, CHANGE_J2000_TO_ICRS, cat_entry::dec, frame_tie(), ICRS_TO_J2000, J2000_TO_ICRS, NOVAS_JD_J2000, NOVAS_KMS, novas_los_to_xyz(), novas_vlen(), novas_xyz_to_los(), cat_entry::parallax, PRECESSION, precession(), cat_entry::promodec, cat_entry::promora, PROPER_MOTION, cat_entry::ra, radec2vector(), cat_entry::radialvelocity, SIZE_OF_CAT_NAME, SIZE_OF_OBJ_NAME, cat_entry::starname, and cat_entry::starnumber.

transform_hip()

int transform_hip	(	const cat_entry *	hipparcos,
		cat_entry *	hip_2000 )

Convert Hipparcos catalog data at epoch J1991.25 to epoch J2000.0, for use within NOVAS. To be used only for Hipparcos or Tycho stars with linear space motion. Both input and output data is in the ICRS.

Parameters

	hipparcos	An entry from the Hipparcos catalog, at epoch J1991.25, with 'ra' in degrees(!) as per Hipparcos catalog units.
[out]	hip_2000	The transformed input entry, at epoch J2000.0, with 'ra' in hours(!) as per the NOVAS convention. It may be the same as the input.

Returns

0 if successful, or -1 if either of the input pointer arguments is NULL.

See also

make_cat_entry()

NOVAS_JD_HIP

References cat_entry::catalog, NOVAS_JD_HIP, cat_entry::ra, and transform_cat().