novas.h File Reference

SuperNOVAS types, definitions, and function prototypes. More...

Data Structures
struct	cat_entry
	Basic astrometric data for any sidereal object located outside the solar system. More...
struct	in_space
	data for an observer's location on Earth orbit More...
struct	novas_delaunay_args
	Fundamental Delaunay arguments of the Sun and Moon, from Simon section 3.4(b.3). More...
struct	novas_frame
	A set of parameters that uniquely define the place and time of observation. More...
struct	novas_matrix
	A 3x3 matrix for coordinate transformations. More...
struct	novas_observable
	Spherical and spectral coordinate set. More...
struct	novas_orbital
	Keplerian orbital elements for NOVAS_ORBITAL_OBJECT type. More...
struct	novas_orbital_system
	Specification of an orbital system, in which orbital elements are defined. More...
struct	novas_planet_bundle
	Position and velocity data for a set of major planets (which may include the Sun and the Moon also). More...
struct	novas_timespec
	A structure, which defines a precise instant of time that can be extpressed in any of the astronomical timescales. More...
struct	novas_track
	The spherical and spectral tracking position of a source, and its first and second time derivatives. More...
struct	novas_transform
	A transformation between two astronomical coordinate systems for the same observer location and time. More...
struct	object
	Celestial object of interest. More...
struct	observer
	Observer location. More...
struct	on_surface
	Data for an observer's location on the surface of the Earth, and optional local weather data for refraction calculations only. More...
struct	ra_of_cio
	[deprecated] More...
struct	sky_pos
	Celestial object's place on the sky; contains the output from place() More...

Macros
#define	ASEC2RAD   (DEG2RAD / 3600.0)
	[rad/arcsec] 1 arcsecond in radians
#define	ASEC360   (360 * 60 * 60)
	[arcsec] Number of arcseconds in 360 degrees.
#define	BARYC   NOVAS_BARYCENTER
	Deprecated.
#define	CAT_ENTRY_INIT
	Initializer for a NOVAS cat_entry structure.
#define	DE405_AU   1.4959787069098932e+11
	[m] Astronomical unit (AU).
#define	DEFAULT_GRAV_BODIES_FULL_ACCURACY   ( DEFAULT_GRAV_BODIES_REDUCED_ACCURACY | (1 << NOVAS_JUPITER) | (1 << NOVAS_SATURN) )
	Default set of gravitating bodies to use for deflection calculations in full accuracy mode.
#define	DEFAULT_GRAV_BODIES_REDUCED_ACCURACY   ( (1 << NOVAS_SUN) )
	Default set of gravitating bodies to use for deflection calculations in reduced accuracy mode.
#define	DEG2RAD   (M_PI / 180.0)
	[rad/deg] 1 degree in radians
#define	HELIOC   NOVAS_HELIOCENTER
	Deprecated.
#define	IN_SPACE_INIT
	Initializer for a NOVAS in_space structure.
#define	M_PI   3.14159265358979323846
	Definition of π in case it's not defined in math.h.
#define	NOVAS_ARCMIN   (NOVAS_DEGREE / 60.0)
	[rad] An arc minute expressed in radians.
#define	NOVAS_ARCSEC   (NOVAS_ARCMIN / 60.0)
	[rad] An arc second expressed in radians.
#define	NOVAS_AU   1.495978707e+11
	[m] Astronomical unit (AU).
#define	NOVAS_AU_KM   ( 1e-3 * NOVAS_AU )
	[km] Astronomical Unit (AU) in kilometers.
#define	NOVAS_AU_SEC   ( NOVAS_AU / NOVAS_C )
	[s] Light-time for one astronomical unit (AU) in seconds.
#define	NOVAS_BESSELIAN_YEAR_DAYS   365.242198781
	[day] The length of a Besselian year in days.
#define	NOVAS_C   299792458.0
	[m/s] Speed of light in meters/second is a defining physical constant.
#define	NOVAS_C_AU_PER_DAY   ( NOVAS_DAY / NOVAS_AU_SEC )
	[AU/day] Speed of light in units of AU/day.
#define	NOVAS_DAY   86400.0
	[s] The length of a synodic day, that is 24 hours exactly.
#define	NOVAS_DEFAULT_DISTANCE   (1e9 * NOVAS_PARSEC)
	[m] Default distance at which sidereal sources are assumed when not specified otherwise Historically NOVAS placed sources with no parallax at 1 Gpc distance, and so we follow.
#define	NOVAS_DEFAULT_WAVELENGTH   0.55
	[μm] Default wavelength, e.g.
#define	NOVAS_DEGREE   (M_PI / 180.0)
	[rad] A degree expressed in radians.
#define	NOVAS_DELAUNAY_ARGS_INIT
	Empty initializer for novas_delaunay_args.
#define	NOVAS_EARTH_ANGVEL   7.2921150e-5
	[rad/s] Rotational angular velocity of Earth from IERS Conventions (2003).
#define	NOVAS_EARTH_FLATTENING   NOVAS_GRS80_FLATTENING
	[m] Earth ellipsoid flattening (ITRF / GRS80_MODEL)
#define	NOVAS_EARTH_INIT
	object initializer for the planet Earth
#define	NOVAS_EARTH_RADIUS   NOVAS_GRS80_RADIUS
	[m] Equatorial radius of Earth (ITRF / GRS80 model)
#define	NOVAS_EMB_INIT
	object initializer for the the Earth-Moon Barycenter (EMB)
#define	NOVAS_EQUATOR_TYPES   (NOVAS_GCRS_EQUATOR + 1)
	The number of equator types defined in enum novas_equator_type.
#define	NOVAS_FRAME_INIT
	Empty initializer for novas_frame.
#define	NOVAS_G_EARTH   3.98600435507e14
	[m3/s2] Geocentric gravitational constant (GMearth) from DE440, see Park et al., AJ, 161, 105 (2021)
#define	NOVAS_G_SUN   1.32712440041279419e20
	[m3/s2] Heliocentric gravitational constant (GMsun) from DE440, see Park et al., AJ, 161, 105 (2021)
#define	NOVAS_GPS_TO_TAI   19.0
	[s] TAI - GPS time offset
#define	NOVAS_GRS80_FLATTENING   (1.0 / 298.257222101)
	[m] WGS84 Earth flattening
#define	NOVAS_GRS80_RADIUS   6378137.0
	[m] Equatorial radius of the WGS84 reference ellipsoid.
#define	NOVAS_HOURANGLE   (M_PI / 12.0)
	[rad] An hour of angle expressed in radians.
#define	NOVAS_ID_TYPES
	Number of different Solar-system body ID types enumerated.
#define	NOVAS_IERS_EARTH_FLATTENING   (1.0 / 298.25642)
	[m] Earth ellipsoid flattening from IERS Conventions (2003).
#define	NOVAS_IERS_EARTH_RADIUS   6378136.6
	[m] Equatorial radius of Earth in meters from IERS Conventions (2003).
#define	NOVAS_JD_B1900   2415020.31352
	[day] Julian date at B1900 (NASA / NAIF SPICE definition) precession(), transform_cat()
#define	NOVAS_JD_B1950   2433282.42345905
	[day] Julian date at B1950 (NASA / NAIF SPICE definition) precession(), transform_cat()
#define	NOVAS_JD_HIP   2448349.0625
	[day] Julian date for J1991.25, which the Hipparcos catalog is referred to.
#define	NOVAS_JD_J2000   2451545.0
	[day] Julian date at J2000
#define	NOVAS_JD_MJD0   2400000.5
	[day] Julian date at which the Modified Julian Date (MJD) is zero
#define	NOVAS_JD_START_GREGORIAN   2299160.5
	[day] The Julian day the Gregorian calendar was introduced in 15 October 1582.
#define	NOVAS_JULIAN_YEAR_DAYS   365.25
	[day] The length of a Julian year (at J2000) in days.
#define	NOVAS_JUPITER_INIT
	object initializer for the planet Jupiter
#define	NOVAS_KM   1000.0
	[m] A kilometer (km) in meters.
#define	NOVAS_KMS   (NOVAS_KM)
	[m] One km/s in m/s.
#define	NOVAS_LIGHT_YEAR   ( NOVAS_C * NOVAS_TROPICAL_YEAR_DAYS * NOVAS_DAY )
	[m] A light-year in meters.
#define	NOVAS_MAJOR_VERSION   3
	Major version of NOVAS on which this library is based.
#define	NOVAS_MARS_INIT
	object initializer for the planet Mars
#define	NOVAS_MATRIX_IDENTITY
	novas_matric initializer for an indentity matrix
#define	NOVAS_MATRIX_INIT
	Empty initializer for novas_matrix.
#define	NOVAS_MERCURY_INIT
	object initializer for the planet Venus
#define	NOVAS_MINOR_VERSION   1
	Minor version of NOVAS on which this library is based.
#define	NOVAS_MOON_INIT
	object initializer for the Moon
#define	NOVAS_NEPTUNE_INIT
	object initializer for the planet Neptune
#define	NOVAS_OBJECT_INIT
	Empty object initializer.
#define	NOVAS_OBJECT_TYPES   (NOVAS_ORBITAL_OBJECT + 1)
	The number of object types distinguished by NOVAS.
#define	NOVAS_OBSERVABLE_INIT
	Empty initializer for novas_observable.
#define	NOVAS_OBSERVER_PLACES   (NOVAS_SOLAR_SYSTEM_OBSERVER + 1)
	The number of observer place types supported.
#define	NOVAS_ORBIT_INIT
	Initializer for novas_orbital for heliocentric orbits using GCRS ecliptic pqrametrization.
#define	NOVAS_ORBITAL_SYSTEM_INIT
	Default orbital system initializer for heliocentric GCRS ecliptic orbits.
#define	NOVAS_ORIGIN_TYPES   (NOVAS_HELIOCENTER + 1)
	The number of different ICSR origins available in NOVAS.
#define	NOVAS_PARSEC   ( NOVAS_AU / NOVAS_ARCSEC )
	[m] A parsec in meters.
#define	NOVAS_PLANET_BUNDLE_INIT
	Empty initializer for novas_planet_bundle.
#define	NOVAS_PLANET_GRAV_Z_INIT
	Gravitational redshifts for major planets (and Moon and Sun) for light emitted at surface and detected at a large distance away.
#define	NOVAS_PLANET_INIT(num, name)
	object initializer macro for major planets, the Sun, Moon, and barycenters.
#define	NOVAS_PLANET_NAMES_INIT
	String array initializer for Major planet names, matching the enum novas_planet.
#define	NOVAS_PLANET_RADII_INIT
	Array initializer for mean planet radii in meters, matching the enum novas_planet.
#define	NOVAS_PLANETS   (NOVAS_PLUTO_BARYCENTER + 1)
	The number of major planets defined in NOVAS.
#define	NOVAS_PLUTO_BARYCENTER_INIT
	object initializer for the Pluto system barycenter
#define	NOVAS_PLUTO_INIT
	object initializer for the minor planet Pluto
#define	NOVAS_REFERENCE_SYSTEMS   (NOVAS_ITRS + 1)
	The number of basic coordinate reference systems in NOVAS.
#define	NOVAS_REFRACTION_MODELS   (NOVAS_WAVE_REFRACTION + 1)
	The number of built-in refraction models available in SuperNOVAS.
#define	NOVAS_RMASS_INIT
	Reciprocal masses of solar system bodies, from DE-405 (Sun mass / body mass).
#define	NOVAS_SATURN_INIT
	object initializer for the planet Saturn
#define	NOVAS_SOLAR_CONSTANT   1367.0
	[W/m2] The Solar Constant i.e., typical incident Solar power on Earth.
#define	NOVAS_SOLAR_RADIUS   696340000.0
	[m] Solar radius (photosphere)
#define	NOVAS_SSB_INIT
	object initializer for the Solar System Barycenter (SSB)
#define	NOVAS_SUN_INIT
	object initializer for the Sun
#define	NOVAS_SYSTEM_B1950   "B1950"
	The B1950 coordiante system as a string.
#define	NOVAS_SYSTEM_FK4   "FK4"
	The 4th catalog of fundamental stars (FK4) coordinate system as a string.
#define	NOVAS_SYSTEM_FK5   "FK5"
	The 5th catalog of fundamental stars (FK5) coordinate system as a string.
#define	NOVAS_SYSTEM_FK6   "FK6"
	The 6th catalog of fundamental stars (FK6) coordinate system as a string.
#define	NOVAS_SYSTEM_HIP   "HIP"
	The Hipparcos dataset coordinate system as a string.
#define	NOVAS_SYSTEM_ICRS   "ICRS"
	The ICRS system as a string.
#define	NOVAS_SYSTEM_J2000   "J2000"
	The J2000 coordinate syste, as a string.
#define	NOVAS_TAI_TO_TT   32.184
	[s] TT - TAI time offset
#define	NOVAS_TIMESCALES   (NOVAS_UT1 + 1)
	The number of asronomical time scales supported.
#define	NOVAS_TIMESPEC_INIT
	Empty initializer for novas_timespec.
#define	NOVAS_TRACK_INIT
	Empty initializer for novas_track.
#define	NOVAS_TRANSFORM_INIT
	Empty initializer for NOVAS_TRANSFORM.
#define	NOVAS_TRANSFORM_TYPES   (ICRS_TO_J2000 + 1)
	The number of coordinate transfor types in NOVAS.
#define	NOVAS_TROPICAL_YEAR_DAYS   365.2421897
	[day] The length of a tropical year (at J2000) in days.
#define	NOVAS_URANUS_INIT
	object initializer for the planet Uranus
#define	NOVAS_VENUS_INIT
	object initializer for the planet Mercury
#define	NOVAS_VERSION_STRING   str_2(NOVAS_MAJOR_VERSION) "." str_2(NOVAS_MINOR_VERSION)
	The version string of the upstream NOVAS library on which this library is based.
#define	NOVAS_WGS84_FLATTENING   (1.0 / 298.257223563)
	[m] WGS84 Earth flattening
#define	NOVAS_WGS84_RADIUS   6378137.0
	[m] Equatorial radius of the WGS84 reference ellipsoid.
#define	NOVAS_WOBBLE_DIRECTIONS   (WOBBLE_PEF_TO_ITRS + 1)
	Number of values in enum novas_wobble_direction.
#define	OBSERVER_INIT
	Empty initializer for observer.
#define	ON_SURFACE_INIT
	Initializer for a NOVAS on_surface data structure.
#define	ON_SURFACE_LOC(lon, lat, alt)
	Initializer for a NOVAS on_surface data structure at a specified geodetic location.
#define	RAD2DEG   (1.0 / DEG2RAD)
	[deg/rad] 1 radian in degrees
#define	SIZE_OF_CAT_NAME   6
	Maximum bytes in catalog IDs including string termination.
#define	SIZE_OF_OBJ_NAME   50
	Maximum bytes in object names including string termination.
#define	SKY_POS_INIT
	Initializer for a NOVAS sky_pos structure.
#define	SUPERNOVAS_MAJOR_VERSION   1
	API major version.
#define	SUPERNOVAS_MINOR_VERSION   5
	API minor version.
#define	SUPERNOVAS_PATCHLEVEL   0
	Integer sub version of the release.
#define	SUPERNOVAS_RELEASE_STRING   "-rc8"
	Additional release information in version, e.g. "-1", or "-rc1", or empty string "" for releases.
#define	SUPERNOVAS_VERSION_STRING
	The version string for this library.
#define	TWOPI   (2.0 * M_PI)
	2π

Typedefs
typedef int(*	novas_ephem_provider) (const char *name, long id, double jd_tdb_high, double jd_tdb_low, enum novas_origin *restrict origin, double *restrict pos, double *restrict vel)
	Function to obtain ephemeris data for minor planets, which are not handled by the solarsystem() type calls.
typedef int(*	novas_nutation_provider) (double jd_tt_high, double jd_tt_low, double *restrict dpsi, double *restrict deps)
	Function type definition for the IAU 2000 nutation series calculation.
typedef short(*	novas_planet_provider) (double jd_tdb, enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	Provides the position and velocity of major planets (as well as the Sun, Moon, Solar-system Barycenter, and other barycenters).
typedef short(*	novas_planet_provider_hp) (const double jd_tdb[2], enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	Provides the position and velocity of major planets (as well as the Sun, Moon, Solar-system Barycenter, and other barycenters).
typedef double(*	RefractionModel) (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
	A function that returns a refraction correction for a given date/time of observation at the given site on earth, and for a given astrometric source elevation.

Enumerations
enum	novas_accuracy { NOVAS_FULL_ACCURACY = 0 , NOVAS_REDUCED_ACCURACY }
	Constants to control the precision of NOVAS nutation calculations. More...
enum	novas_calendar_type { NOVAS_ROMAN_CALENDAR = -1 , NOVAS_ASTRONOMICAL_CALENDAR , NOVAS_GREGORIAN_CALENDAR }
	Constants to disambiguate which type of calendar yo use for interpreting calendar dates. More...
enum	novas_cio_location_type { CIO_VS_GCRS = 1 , CIO_VS_EQUINOX }
enum	novas_date_format { NOVAS_YMD = 0 , NOVAS_DMY , NOVAS_MDY }
	The general order of date components for parsing. More...
enum	novas_debug_mode { NOVAS_DEBUG_OFF = 0 , NOVAS_DEBUG_ON , NOVAS_DEBUG_EXTRA }
	Settings for 'novas_debug()'. More...
enum	novas_dynamical_type { NOVAS_DYNAMICAL_MOD = 0 , NOVAS_DYNAMICAL_TOD , NOVAS_DYNAMICAL_CIRS }
	Constants that determine the type of dynamical system. More...
enum	novas_earth_rotation_measure { EROT_ERA = 0 , EROT_GST }
enum	novas_equator_type { NOVAS_MEAN_EQUATOR = 0 , NOVAS_TRUE_EQUATOR , NOVAS_GCRS_EQUATOR }
	Constants that determine the type of equator to be used for the coordinate system. More...
enum	novas_equatorial_class { NOVAS_REFERENCE_CLASS = 0 , NOVAS_DYNAMICAL_CLASS }
enum	novas_equinox_type { NOVAS_MEAN_EQUINOX = 0 , NOVAS_TRUE_EQUINOX }
	The type of equinox used in the pre IAU 2006 (old) methodology. More...
enum	novas_frametie_direction { J2000_TO_ICRS = -1 , ICRS_TO_J2000 }
	Direction constant to use for frame_tie(), to determine the direction of transformation between J2000 and ICRS coordinates. More...
enum	novas_id_type { NOVAS_ID_NAIF = 0 , NOVAS_ID_CALCEPH }
	Solar-system body IDs to use as object.number with NOVAS_EPHEM_OBJECT types. More...
enum	novas_nutation_direction { NUTATE_TRUE_TO_MEAN = -1 , NUTATE_MEAN_TO_TRUE }
	Direction constant for nutation(), between mean and true equatorial coordinates. More...
enum	novas_object_type { NOVAS_PLANET = 0 , NOVAS_EPHEM_OBJECT , NOVAS_CATALOG_OBJECT , NOVAS_ORBITAL_OBJECT }
	The type of astronomical objects distinguied by the NOVAS library. More...
enum	novas_observer_place {   NOVAS_OBSERVER_AT_GEOCENTER = 0 , NOVAS_OBSERVER_ON_EARTH , NOVAS_OBSERVER_IN_EARTH_ORBIT , NOVAS_AIRBORNE_OBSERVER ,   NOVAS_SOLAR_SYSTEM_OBSERVER }
	Types of places on and around Earth that may serve a a reference position for the observation. More...
enum	novas_origin { NOVAS_BARYCENTER = 0 , NOVAS_HELIOCENTER }
	The origin of the ICRS system for referencing positions and velocities for solar-system bodies. More...
enum	novas_planet {   NOVAS_SSB = 0 , NOVAS_MERCURY , NOVAS_VENUS , NOVAS_EARTH ,   NOVAS_MARS , NOVAS_JUPITER , NOVAS_SATURN , NOVAS_URANUS ,   NOVAS_NEPTUNE , NOVAS_PLUTO , NOVAS_SUN , NOVAS_MOON ,   NOVAS_EMB , NOVAS_PLUTO_BARYCENTER }
	Enumeration for the 'major planet' numbers in NOVAS to use as the solar-system body number whenever the object type is NOVAS_PLANET. More...
enum	novas_pole_offset_type { POLE_OFFSETS_DPSI_DEPS = 1 , POLE_OFFSETS_X_Y }
enum	novas_reference_ellipsoid { NOVAS_GRS80_ELLIPSOID = 0 , NOVAS_WGS84_ELLIPSOID , NOVAS_IERS_1989_ELLIPSOID , NOVAS_IERS_2003_ELLIPSOID }
	Type of Earth reference ellipsoid. More...
enum	novas_reference_plane { NOVAS_ECLIPTIC_PLANE = 0 , NOVAS_EQUATORIAL_PLANE }
	The plane in which values, such as orbital parameters are referenced. More...
enum	novas_reference_system {   NOVAS_GCRS = 0 , NOVAS_TOD , NOVAS_CIRS , NOVAS_ICRS ,   NOVAS_J2000 , NOVAS_MOD , NOVAS_TIRS , NOVAS_ITRS }
	The basic types of positional coordinate reference systems supported by NOVAS. More...
enum	novas_refraction_model {   NOVAS_NO_ATMOSPHERE = 0 , NOVAS_STANDARD_ATMOSPHERE , NOVAS_WEATHER_AT_LOCATION , NOVAS_RADIO_REFRACTION ,   NOVAS_WAVE_REFRACTION }
	Constants that determine whether what model (if any) to use for implicit refraction calculations. More...
enum	novas_refraction_type { NOVAS_REFRACT_OBSERVED = -1 , NOVAS_REFRACT_ASTROMETRIC }
	The type of elevation value for which to calculate a refraction. More...
enum	novas_separator_type { NOVAS_SEP_COLONS = 0 , NOVAS_SEP_SPACES , NOVAS_SEP_UNITS , NOVAS_SEP_UNITS_AND_SPACES }
	Separator type to use for broken-down time/angle string representations in HMS/DMS formats. More...
enum	novas_timescale {   NOVAS_TCB = 0 , NOVAS_TDB , NOVAS_TCG , NOVAS_TT ,   NOVAS_TAI , NOVAS_GPS , NOVAS_UTC , NOVAS_UT1 }
	Constants to reference various astrnomical timescales used. More...
enum	novas_transform_type {   PROPER_MOTION = 1 , PRECESSION , CHANGE_EPOCH , CHANGE_J2000_TO_ICRS ,   CHANGE_ICRS_TO_J2000 }
	The types of coordinate transformations available for tranform_cat(). More...
enum	novas_wobble_direction { WOBBLE_ITRS_TO_TIRS = 0 , WOBBLE_TIRS_TO_ITRS , WOBBLE_ITRS_TO_PEF , WOBBLE_PEF_TO_ITRS }
	Direction constants for polar wobble corrections via the wobble() function. More...

Functions
int	aberration (const double *pos, const double *vobs, double lighttime, double *out)
	Corrects position vector for aberration of light.
double	accum_prec (double t)
	Returns the general precession in longitude (Simon et al.
short	app_planet (double jd_tt, const object *restrict ss_body, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis)
	reference_system: TOD observer location: geocenter position_type: apparent
short	app_star (double jd_tt, const cat_entry *restrict star, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec)
	reference_system: TOD observer location: geocenter position_type: apparent
double	app_to_cirs_ra (double jd_tt, enum novas_accuracy accuracy, double ra)
	Converts an apparent right ascension coordinate (measured from the true equinox of date) to a CIRS R.A., measured from the CIO.
short	astro_planet (double jd_tt, const object *restrict ss_body, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis)
	reference_system: ICRS / GCRS observer location: geocenter position_type: geometric
short	astro_star (double jd_tt, const cat_entry *restrict star, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec)
	reference_system: ICRS / GCRS observer location: geocenter position_type: geometric
int	bary2obs (const double *pos, const double *pos_obs, double *out, double *restrict lighttime)
	Moves the origin of coordinates from the barycenter of the solar system to the observer (or the geocenter); i.e., this function accounts for parallax (annual+geocentric or just annual).
int	cal_date (double tjd, short *restrict year, short *restrict month, short *restrict day, double *restrict hour)
	This function will compute a broken down date on the astronomical calendar given the Julian day input.
short	cel2ter (double jd_ut1_high, double jd_ut1_low, double ut1_to_tt, enum novas_earth_rotation_measure erot, enum novas_accuracy accuracy, enum novas_equatorial_class coordType, double xp, double yp, const double *in, double *out)
short	cel_pole (double jd_tt, enum novas_pole_offset_type type, double dpole1, double dpole2)
short	cio_array (double jd_tdb, long n_pts, ra_of_cio *restrict cio)
short	cio_basis (double jd_tdb, double ra_cio, enum novas_cio_location_type loc_type, enum novas_accuracy accuracy, double *restrict x, double *restrict y, double *restrict z)
short	cio_location (double jd_tdb, enum novas_accuracy accuracy, double *restrict ra_cio, short *restrict loc_type)
short	cio_ra (double jd_tt, enum novas_accuracy accuracy, double *restrict ra_cio)
	Computes the true right ascension of the celestial intermediate origin (CIO) vs the equinox of date on the true equator of date for a given TT Julian date.
double	cirs_to_app_ra (double jd_tt, enum novas_accuracy accuracy, double ra)
	Converts a CIRS right ascension coordinate (measured from the CIO) to an apparent R.A.
int	cirs_to_gcrs (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the Celestial Intermediate Reference System (CIRS) frame at the given epoch to the ICRS / GCRS.
int	cirs_to_itrs (double jd_tt_high, double jd_tt_low, double ut1_to_tt, enum novas_accuracy accuracy, double xp, double yp, const double *in, double *out)
	Rotates a position vector from the dynamical CIRS frame of date to the Earth-fixed ITRS frame (IAU 2000 standard method).
int	cirs_to_tod (double jd_tt, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the Celestial Intermediate Reference System (CIRS) at the given epoch to the True of Date (TOD) reference system.
double	d_light (const double *pos_src, const double *pos_body)
	Returns the difference in light-time, for a star, between the barycenter of the solar system and the observer (or the geocenter) (Usage A).
int	e_tilt (double jd_tdb, enum novas_accuracy accuracy, double *restrict mobl, double *restrict tobl, double *restrict ee, double *restrict dpsi, double *restrict deps)
	(primarily for internal use) Computes quantities related to the orientation of the Earth's rotation axis at the specified Julian date.
short	earth_sun_calc (double jd_tdb, enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	Provides the position and velocity of the Earth and Sun only at epoch 'jd_tdb' by evaluating a closed-form theory without reference to an external file.
short	earth_sun_calc_hp (const double jd_tdb[restrict 2], enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	It may provide the position and velocity of the Earth and Sun, the same as earth_sun_calc(), if enable_earth_sun_hp() is set to true (non-zero).
int	ecl2equ (double jd_tt, enum novas_equator_type coord_sys, enum novas_accuracy accuracy, double elon, double elat, double *restrict ra, double *restrict dec)
	Convert ecliptic longitude and latitude to right ascension and declination.
short	ecl2equ_vec (double jd_tt, enum novas_equator_type coord_sys, enum novas_accuracy accuracy, const double *in, double *out)
	Converts an ecliptic position vector to an equatorial position vector.
void	enable_earth_sun_hp (int value)
	Specify whether the high-precision call is allowed to return a low-precision result.
short	ephemeris (const double *restrict jd_tdb, const object *restrict body, enum novas_origin origin, enum novas_accuracy accuracy, double *restrict pos, double *restrict vel)
	Retrieves the position and velocity of a solar system body using the currently configured plugins that provide them.
short	equ2ecl (double jd_tt, enum novas_equator_type coord_sys, enum novas_accuracy accuracy, double ra, double dec, double *restrict elon, double *restrict elat)
	Convert right ascension and declination to ecliptic longitude and latitude.
short	equ2ecl_vec (double jd_tt, enum novas_equator_type coord_sys, enum novas_accuracy accuracy, const double *in, double *out)
	Converts an equatorial position vector to an ecliptic position vector.
int	equ2gal (double ra, double dec, double *restrict glon, double *restrict glat)
	Converts ICRS right ascension and declination to galactic longitude and latitude.
int	equ2hor (double jd_ut1, double ut1_to_tt, enum novas_accuracy accuracy, double xp, double yp, const on_surface *restrict location, double ra, double dec, enum novas_refraction_model ref_option, double *restrict zd, double *restrict az, double *restrict rar, double *restrict decr)
double	era (double jd_ut1_high, double jd_ut1_low)
	Returns the value of the Earth Rotation Angle (θ) for a given UT1 Julian date.
int	frame_tie (const double *in, enum novas_frametie_direction direction, double *out)
	Transforms a vector from the dynamical reference system to the International Celestial Reference System (ICRS), or vice versa.
int	fund_args (double t, novas_delaunay_args *restrict a)
	Compute the fundamental (a.k.a.
int	gal2equ (double glon, double glat, double *restrict ra, double *restrict dec)
	Converts galactic longitude and latitude to ICRS right ascension and declination.
short	gcrs2equ (double jd_tt, enum novas_dynamical_type sys, enum novas_accuracy accuracy, double rag, double decg, double *restrict ra, double *restrict dec)
	Converts GCRS right ascension and declination to coordinates with respect to the equator of date (mean or true).
int	gcrs_to_cirs (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the ICRS / GCRS to the Celestial Intermediate Reference System (CIRS) frame at the given epoch.
int	gcrs_to_j2000 (const double *in, double *out)
	Changes ICRS / GCRS coordinates to J2000 coordinates.
int	gcrs_to_mod (double jd_tdb, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the ICRS / GCRS to the Mean of Date (MOD) reference frame at the given epoch.
int	gcrs_to_tod (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the ICRS / GCRS to the True of Date (TOD) reference frame at the given epoch.
short	geo_posvel (double jd_tt, double ut1_to_tt, enum novas_accuracy accuracy, const observer *restrict obs, double *restrict pos, double *restrict vel)
	Computes the geocentric GCRS position and velocity of an observer.
novas_ephem_provider	get_ephem_provider ()
	Returns the user-defined ephemeris accessor function.
novas_nutation_provider	get_nutation_lp_provider ()
	Returns the function configured for low-precision IAU 2000 nutation calculations instead of the default nu2000k().
novas_planet_provider	get_planet_provider ()
	Returns the custom (low-precision) ephemeris provider function for major planets (and Sun, Moon, SSB...), if any.
novas_planet_provider_hp	get_planet_provider_hp ()
	Returns the custom high-precision ephemeris provider function for major planets (and Sun, Moon, SSB...), if any.
double	get_ut1_to_tt (int leap_seconds, double dut1)
	Returns the TT - UT1 time difference given the leap seconds and the actual UT1 - UTC time difference as measured and published by IERS.
double	get_utc_to_tt (int leap_seconds)
	Returns the difference between Terrestrial Time (TT) and Universal Coordinated Time (UTC)
short	grav_def (double jd_tdb, enum novas_observer_place unused, enum novas_accuracy accuracy, const double *pos_src, const double *pos_obs, double *out)
	(primarily for internal use) Computes the total gravitational deflection of light for the observed object due to the major gravitating bodies in the solar system.
int	grav_planets (const double *pos_src, const double *pos_obs, const novas_planet_bundle *restrict planets, double *out)
	(primarily for internal use) Computes the total gravitational deflection of light for the observed object due to the specified gravitating bodies in the solar system.
double	grav_redshift (double M_kg, double r_m)
	Returns the gravitational redshift (z) for light emitted near a massive spherical body at some distance from its center, and observed at some very large (infinite) distance away.
int	grav_undef (double jd_tdb, enum novas_accuracy accuracy, const double *pos_app, const double *pos_obs, double *out)
	(primarily for internal use) Computes the gravitationally undeflected position of an observed source position due to the major gravitating bodies in the solar system.
int	grav_undo_planets (const double *pos_app, const double *pos_obs, const novas_planet_bundle *restrict planets, double *out)
	(primarily for internal use) Computes the gravitationally undeflected position of an observed source position due to the specified Solar-system bodies.
int	grav_vec (const double *pos_src, const double *pos_obs, const double *pos_body, double rmass, double *out)
	(primarily for internal use) Corrects position vector for the deflection of light in the gravitational field of anarbitrary body.
int	hor_to_itrs (const on_surface *restrict location, double az, double za, double *restrict itrs)
	Converts astrometric (unrefracted) azimuth and zenith angles at the specified observer location to a unit position vector in the Earth-fixed ITRS frame.
int	iau2000a (double jd_tt_high, double jd_tt_low, double *restrict dpsi, double *restrict deps)
	Computes the IAU 2000A high-precision nutation series for the specified date, to 0.1 μas accuracy.
int	iau2000b (double jd_tt_high, double jd_tt_low, double *restrict dpsi, double *restrict deps)
	Computes the forced nutation of the non-rigid Earth based at reduced precision.
double	ira_equinox (double jd_tdb, enum novas_equinox_type equinox, enum novas_accuracy accuracy)
	Compute the intermediate right ascension of the equinox at the input Julian date, using an analytical expression for the accumulated precession in right ascension.
int	itrs_to_cirs (double jd_tt_high, double jd_tt_low, double ut1_to_tt, enum novas_accuracy accuracy, double xp, double yp, const double *in, double *out)
	Rotates a position vector from the Earth-fixed ITRS frame to the dynamical CIRS frame of date (IAU 2000 standard method).
int	itrs_to_hor (const on_surface *restrict location, const double *restrict itrs, double *restrict az, double *restrict za)
	Converts a position vector in the Earth-fixed ITRS frame to astrometric (unrefracted) azimuth and zenith angles at the specified observer location.
int	itrs_to_tod (double jd_tt_high, double jd_tt_low, double ut1_to_tt, enum novas_accuracy accuracy, double xp, double yp, const double *in, double *out)
	Rotates a position vector from the Earth-fixed ITRS frame to the dynamical True of Date (TOD) frame of date (pre IAU 2000 method).
int	j2000_to_gcrs (const double *in, double *out)
	Change J2000 coordinates to ICRS / GCRS coordinates.
int	j2000_to_tod (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from J2000 coordinates to the True of Date (TOD) reference frame at the given epoch.
double	julian_date (short year, short month, short day, double hour)
	Returns the Julian day for a given astronomical calendar date.
short	light_time (double jd_tdb, const object *restrict body, const double *pos_obs, double tlight0, enum novas_accuracy accuracy, double *pos_src_obs, double *restrict tlight)
	Computes the geocentric position of a solar system body, as antedated for light-time.
int	light_time2 (double jd_tdb, const object *restrict body, const double *restrict pos_obs, double tlight0, enum novas_accuracy accuracy, double *p_src_obs, double *restrict v_ssb, double *restrict tlight)
	Computes the geocentric position and velocity of a solar system body, as antedated for light-time.
int	limb_angle (const double *pos_src, const double *pos_obs, double *restrict limb_ang, double *restrict nadir_ang)
	Determines the angle of an object above or below the Earth's limb (horizon).
short	local_planet (double jd_tt, const object *restrict ss_body, double ut1_to_tt, const on_surface *restrict position, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis)
	reference_system: ICRS/GCRS observer location: topocentric (on Earth) position_type: apparent
short	local_star (double jd_tt, double ut1_to_tt, const cat_entry *restrict star, const on_surface *restrict position, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec)
	reference_system: ICRS / GCRS observer location: topocentric (on Earth) position_type: apparent
int	make_airborne_observer (const on_surface *location, const double *vel, observer *obs)
	Populates an 'observer' data structure for an observer moving relative to the surface of Earth, such as an airborne observer.
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.
int	make_cat_object (const cat_entry *star, object *source)
	Populates and object data structure with the data for a catalog source.
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.
int	make_ephem_object (const char *name, long num, object *body)
	Sets a celestial object to be a Solar-system ephemeris body.
int	make_gps_observer (double latitude, double longitude, double height, observer *obs)
	Initializes an observer data structure for a ground-based observer with the specified GPS / WGS84 location, and sets mean (annual) weather parameters based on that location.
int	make_gps_site (double latitude, double longitude, double height, on_surface *site)
	Initializes an observing site with the specified GPS / WGS84 location, and sets mean (annual) weather parameters based on that location.
int	make_in_space (const double *sc_pos, const double *sc_vel, in_space *loc)
	Populates an 'in_space' data structure, for an observer situated on a near-Earth spacecraft, with the provided position and velocity components.
int	make_itrf_observer (double latitude, double longitude, double height, observer *obs)
	Initializes an observer data structure for a ground-based observer with the specified International Terrestrial Reference Frame (ITRF) / GRS80 location, and sets mean (annual) weather parameters based on that location.
int	make_itrf_site (double latitude, double longitude, double height, on_surface *site)
	Initializes an observing site with the specified International Terrestrial Reference Frame (ITRF) / GRS80 location, and sets mean (annual) weather parameters based on that location.
short	make_object (enum novas_object_type, long number, const char *name, const cat_entry *star, object *source)
short	make_observer (enum novas_observer_place, const on_surface *loc_surface, const in_space *loc_space, observer *obs)
int	make_observer_at_geocenter (observer *restrict obs)
	Populates an 'observer' data structure for a hypothetical observer located at Earth's geocenter.
int	make_observer_at_site (const on_surface *restrict site, observer *restrict obs)
	Initializes an observer data structure for a ground-based observer at the specified observing site, and sets mean (annual) weather parameters based on that location.
int	make_observer_in_space (const double *sc_pos, const double *sc_vel, observer *obs)
	Populates an 'observer' data structure, for an observer situated on a near-Earth spacecraft, with the specified geocentric position and velocity vectors.
int	make_observer_on_surface (double latitude, double longitude, double height, double temperature, double pressure, observer *restrict obs)
int	make_on_surface (double latitude, double longitude, double height, double temperature, double pressure, on_surface *restrict loc)
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.
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.
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.
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.
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.
int	make_solar_system_observer (const double *sc_pos, const double *sc_vel, observer *obs)
	Populates an 'observer' data structure, for an observer situated on a near-Earth spacecraft, with the specified geocentric position and velocity vectors.
int	make_xyz_site (const double *restrict xyz, on_surface *restrict site)
	Initializes an observing site with the specified Cartesian geocentric xyz location, and sets mean (annual) weather parameters based on that location.
double	mean_obliq (double jd_tdb)
	Computes the mean obliquity of the ecliptic.
short	mean_star (double jd_tt, double tra, double tdec, enum novas_accuracy accuracy, double *restrict ira, double *restrict idec)
	reference system: TOD → ICRS observer location: geocenter → SSB position_type: apparent → geometric
int	mod_to_gcrs (double jd_tdb, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from Mean of Date (MOD) reference frame at the given epoch to the ICRS / GCRS.
enum novas_planet	naif_to_novas_planet (long id)
	Converts a NAIF ID to a NOVAS major planet ID.
int	novas_app_to_geom (const novas_frame *restrict frame, enum novas_reference_system sys, double ra, double dec, double dist, double *restrict geom_icrs)
	Converts an observed apparent sky position of a source to an ICRS geometric position, by undoing the gravitational deflection and aberration corrections.
int	novas_app_to_hor (const novas_frame *restrict frame, enum novas_reference_system sys, double ra, double dec, RefractionModel ref_model, double *restrict az, double *restrict el)
	Converts an observed apparent position vector in the specified coordinate system to local horizontal coordinates in the specified observer frame.
int	novas_approx_heliocentric (enum novas_planet id, double jd_tdb, double *restrict pos, double *restrict vel)
	Returns the approximate geometric heliocentric orbital positions and velocities for the major planets, Sun, or Earth-Moon Barycenter (EMB).
int	novas_approx_sky_pos (enum novas_planet id, const novas_frame *restrict frame, enum novas_reference_system sys, sky_pos *restrict out)
	Calculates an approximate apparent location on sky for a major planet, Sun, Moon, Earth-Moon Barycenter (EMB) – typically to arcmin level accuracy – using Keplerian orbital elements.
int	novas_cartesian_to_geodetic (const double *restrict xyz, enum novas_reference_ellipsoid ellipsoid, double *restrict lon, double *restrict lat, double *restrict alt)
	Converts geocentric Cartesian site coordinates to geodetic coordinates on the given reference ellipsoid.
void	novas_case_sensitive (int value)
	Enables or disables case-sensitive processing of the object name.
int	novas_change_observer (const novas_frame *orig, const observer *obs, novas_frame *out)
	Change the observer location for an observing frame.
double	novas_clock_skew (const novas_frame *frame, enum novas_timescale timescale)
	Returns the instantaneous incremental rate at which the observer's clock (i.e.
double	novas_date (const char *restrict date)
	Returns a Julian date (in non-specific timescale) corresponding the specified input string date / time.
double	novas_date_scale (const char *restrict date, enum novas_timescale *restrict scale)
	Returns a Julian date and the timescale corresponding the specified input string date/time and timescale marker.
int	novas_day_of_week (double tjd)
	Returns the one-based ISO 8601 day-of-week index of a given Julian Date.
int	novas_day_of_year (double tjd, enum novas_calendar_type calendar, int *restrict year)
	Returns the one-based day index in the calendar year for a given Julian Date.
void	novas_debug (enum novas_debug_mode mode)
	Enables or disables reporting errors and traces to the standard error stream.
double	novas_diff_tcb (const novas_timespec *t1, const novas_timespec *t2)
	Returns the Barycentric Coordinate Time (TCB) based time difference (t1 - t2) in days between two astronomical time specifications.
double	novas_diff_tcg (const novas_timespec *t1, const novas_timespec *t2)
	Returns the Geocentric Coordinate Time (TCG) based time difference (t1 - t2) in days between two astronomical time specifications.
double	novas_diff_time (const novas_timespec *t1, const novas_timespec *t2)
	Returns the Terrestrial Time (TT) based time difference (t1 - t2) in days between two astronomical time specifications.
int	novas_diurnal_eop (double gmst, const novas_delaunay_args *restrict delaunay, double *restrict xp, double *restrict yp, double *restrict dut1)
	Calculate corrections to the Earth orientation parameters (EOP) due to short term (diurnal and semidiurnal) libration and the ocean tides.
int	novas_diurnal_eop_at_time (const novas_timespec *restrict time, double *restrict dxp, double *restrict dyp, double *restrict dut1)
	Calculate corrections to the Earth orientation parameters (EOP) due to short term (diurnal and semidiurnal) libration and the ocean tides at a given astromtric time.
int	novas_diurnal_libration (double gmst, const novas_delaunay_args *restrict delaunay, double *restrict xp, double *restrict yp, double *restrict dut1)
	Calculate diurnal and semi-diurnal libration corrections to the Earth orientation parameters (EOP) for the non-rigid Earth.
int	novas_diurnal_ocean_tides (double gmst, const novas_delaunay_args *restrict delaunay, double *restrict xp, double *restrict yp, double *restrict dut1)
	Calculate corrections to the Earth orientation parameters (EOP) due to the ocean tides.
double	novas_dms_degrees (const char *restrict dms)
	Returns the decimal degrees for a DMS string specification.
int	novas_e2h_offset (double dra, double ddec, double pa, double *restrict daz, double *restrict del)
	Converts coordinate offsets, from the local equatorial system to local horizontal offsets.
double	novas_epa (double ha, double dec, double lat)
	Returns the Parallactic Angle (PA) calculated for an RA/Dec location of the sky at a given sidereal time.
double	novas_epoch (const char *restrict system)
	Returns the Julian day corresponding to an astronomical coordinate epoch.
double	novas_equ_sep (double ra1, double dec1, double ra2, double dec2)
	Returns the angular separation of two equatorial locations on a sphere.
int	novas_equ_track (const object *restrict source, const novas_frame *restrict frame, double dt, novas_track *restrict track)
	Calculates equatorial tracking position and motion (first and second time derivatives) for the specified source in the given observing frame.
double	novas_frame_lst (const novas_frame *restrict frame)
	Returns the Local (apparent) Sidereal Time for an observing frame of an Earth-bound observer.
double	novas_gast (double jd_ut1, double ut1_to_tt, enum novas_accuracy accuracy)
	Returns the Greenwich Apparent Sidereal Time (GAST) for a given UT1 date.
int	novas_geodetic_to_cartesian (double lon, double lat, double alt, enum novas_reference_ellipsoid ellipsoid, double *xyz)
	Converts geodetic site coordinates to geocentric Cartesian coordinates, using the specified reference ellipsoid.
int	novas_geodetic_transform_site (enum novas_reference_ellipsoid from_ellipsoid, const on_surface *in, enum novas_reference_ellipsoid to_ellipsoid, on_surface *out)
	Transforms a geodetic location from one reference ellipsoid to another.
int	novas_geom_posvel (const object *restrict source, const novas_frame *restrict frame, enum novas_reference_system sys, double *restrict pos, double *restrict vel)
	Calculates the geometric position and velocity vectors, relative to the observer, for a source in the given observing frame, in the specified coordinate system of choice.
int	novas_geom_to_app (const novas_frame *restrict frame, const double *restrict pos, enum novas_reference_system sys, sky_pos *restrict out)
	Converts an geometric position in ICRS to an apparent position on sky, by applying appropriate corrections for aberration and gravitational deflection for the observer's frame.
enum novas_debug_mode	novas_get_debug_mode ()
	Returns the current, thread-local, mode for reporting errors encountered (and traces).
double	novas_get_split_time (const novas_timespec *restrict time, enum novas_timescale timescale, long *restrict ijd)
	Returns the fractional Julian date of an astronomical time in the specified timescale, as an integer and fractional part.
double	novas_get_time (const novas_timespec *restrict time, enum novas_timescale timescale)
	Returns the fractional Julian date of an astronomical time in the specified timescale.
time_t	novas_get_unix_time (const novas_timespec *restrict time, long *restrict nanos)
	Returns the UNIX time for an astronomical time instant.
double	novas_gmst (double jd_ut1, double ut1_to_tt)
	Returns the Greenwich Mean Sidereal Time (GMST) for a given UT1 date, using eq.
int	novas_h2e_offset (double daz, double del, double pa, double *restrict dra, double *restrict ddec)
	Converts coordinate offsets, from the local horizontal system to local equatorial offsets.
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.
double	novas_hms_hours (const char *restrict hms)
	Returns the decimal hours for a HMS string specification.
int	novas_hor_to_app (const novas_frame *restrict frame, double az, double el, RefractionModel ref_model, enum novas_reference_system sys, double *restrict ra, double *restrict dec)
	Converts an observed azimuth and elevation coordinate to right ascension (R.A.) and declination coordinates expressed in the coordinate system of choice.
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.
double	novas_hpa (double az, double el, double lat)
	Returns the Parallactic Angle (PA) calculated for a horizontal Az/El location of the sky.
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.
double	novas_inv_refract (RefractionModel model, double jd_tt, const on_surface *restrict loc, enum novas_refraction_type type, double el0)
	Computes the reverse atmospheric refraction for a given refraction model.
int	novas_invert_transform (const novas_transform *transform, novas_transform *inverse)
	Inverts a novas coordinate transformation matrix.
int	novas_iso_timestamp (const novas_timespec *restrict time, char *restrict dst, int maxlen)
	Prints a UTC-based ISO timestamp to millisecond precision to the specified string buffer.
int	novas_itrf_transform (int from_year, const double *restrict from_coords, const double *restrict from_rates, int to_year, double *to_coords, double *to_rates)
	Converts ITRF coordinates between different realizations of the ITRF coordinate system.
int	novas_itrf_transform_eop (int from_year, double from_xp, double from_yp, double from_dut1, int to_year, double *restrict to_xp, double *restrict to_yp, double *restrict to_dut1)
	Transforms Earth orientation parameters (xp, yp, dUT1) from one ITRF realization to another.
int	novas_itrf_transform_site (int from_year, const on_surface *in, int to_year, on_surface *out)
	Transforms a geodetic location between two International Terrestrial Reference Frame (ITRF) realizations.
double	novas_jd_from_date (enum novas_calendar_type calendar, int year, int month, int day, double hour)
	Returns the Julian day for a given calendar date.
int	novas_jd_to_date (double tjd, enum novas_calendar_type calendar, int *restrict year, int *restrict month, int *restrict day, double *restrict hour)
	This function will compute a broken down date on the specified calendar for given the Julian day input.
int	novas_los_to_xyz (const double *los, double lon, double lat, double *xyz)
	Converts a 3D line-of-sight vector (δφ, δθ δr) to a rectangular equatorial (δx, δy, δz) vector.
double	novas_lsr_to_ssb_vel (double epoch, double ra, double dec, double vLSR)
	Returns a Solar System Baricentric (SSB) radial velocity for a radial velocity that is referenced to the Local Standard of Rest (LSR).
int	novas_make_frame (enum novas_accuracy accuracy, const observer *obs, const novas_timespec *time, double xp, double yp, novas_frame *frame)
	Sets up a observing frame for a specific observer location, time of observation, and accuracy requirement.
int	novas_make_moon_orbit (double jd_tdb, novas_orbital *restrict orbit)
	Gets the current orbital elements for the Moon relative to the geocenter for the specified epoch of observation.
int	novas_make_planet_orbit (enum novas_planet id, double jd_tdb, novas_orbital *restrict orbit)
	Get approximate current heliocentric orbital elements for the major planets.
int	novas_make_transform (const novas_frame *frame, enum novas_reference_system from_system, enum novas_reference_system to_system, novas_transform *transform)
	Calculates a transformation matrix that can be used to convert positions and velocities from one coordinate reference system to another.
double	novas_mean_clock_skew (const novas_frame *frame, enum novas_timescale timescale)
	Returns the averaged incremental rate at which the observer's clock (i.e.
double	novas_moon_angle (const object *restrict source, const novas_frame *restrict frame)
	Returns the apparent angular distance of a source from the Moon from the observer's point of view.
double	novas_moon_phase (double jd_tdb)
	Calculates the Moon's phase at a given time.
double	novas_next_moon_phase (double phase, double jd_tdb)
	Calculates the date / time at which the Moon will reach the specified phase next, after the specified time.
double	novas_norm_ang (double angle)
	Returns the normalized angle in the [0:2π) range.
double	novas_object_sep (const object *source1, const object *source2, const novas_frame *restrict frame)
	Returns the angular separation of two objects from the observer's point of view.
int	novas_offset_time (const novas_timespec *time, double seconds, novas_timespec *out)
	Increments the astrometric time by a given amount.
double	novas_optical_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
	Returns an optical refraction correction using the weather parameters defined for the observer location.
int	novas_orbit_native_posvel (double jd_tdb, const novas_orbital *restrict orbit, double *restrict pos, double *restrict vel)
	Calculates a rectangular equatorial position and velocity vector for the given orbital elements for the specified time of observation, in the native coordinate system in which the orbital is defined (e.g.
int	novas_orbit_posvel (double jd_tdb, const novas_orbital *restrict orbit, enum novas_accuracy accuracy, double *restrict pos, double *restrict vel)
	Calculates a rectangular equatorial position and velocity vector for the given orbital elements for the specified time of observation.
double	novas_parse_date (const char *restrict date, char **restrict tail)
	Parses an astronomical date/time string into a Julian date specification.
double	novas_parse_date_format (enum novas_calendar_type calendar, enum novas_date_format format, const char *restrict date, char **restrict tail)
	Parses a calendar date/time string, expressed in the specified type of calendar, into a Julian day (JD).
double	novas_parse_degrees (const char *restrict str, char **restrict tail)
	Parses an angle in degrees from a string that contains either a decimal degrees or else a broken-down DMS representation.
double	novas_parse_dms (const char *restrict str, char **restrict tail)
	Parses the decimal degrees for a DMS string specification.
double	novas_parse_hms (const char *restrict str, char **restrict tail)
	Parses the decimal hours for a HMS string specification.
double	novas_parse_hours (const char *restrict str, char **restrict tail)
	Parses a time or time-like angle from a string that contains either a decimal hours or else a broken-down HMS representation.
double	novas_parse_iso_date (const char *restrict date, char **restrict tail)
	Parses an ISO 8601 timestamp, converting it to a Julian day.
enum novas_timescale	novas_parse_timescale (const char *restrict str, char **restrict tail)
	Parses the timescale from a string containing a standard abbreviation (case insensitive), and returns the updated parse position after the timescale specification (if any).
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.
int	novas_print_dms (double degrees, enum novas_separator_type sep, int decimals, char *restrict buf, int len)
	Prints an angle in degrees as [-]ddd:mm:ss[.S...] into the specified buffer, with up to nanosecond precision.
int	novas_print_hms (double hours, enum novas_separator_type sep, int decimals, char *restrict buf, int len)
	Prints a time in hours as hh:mm:ss[.S...] into the specified buffer, with up to nanosecond precision.
int	novas_print_timescale (enum novas_timescale scale, char *restrict buf)
	Prints the standard string representation of the timescale to the specified buffer.
double	novas_radio_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
	Atmospheric refraction model for radio wavelengths (Berman & Rockwell 1976).
int	novas_refract_wavelength (double microns)
	Sets the observing wavelength for which refraction is to be calculated when using a wavelength-depenendent model, such as novas_wave_refraction().
double	novas_rises_above (double el, const object *restrict source, const novas_frame *restrict frame, RefractionModel ref_model)
	Returns the UTC date at which a distant source appears to rise above the specified elevation angle.
double	novas_sep (double lon1, double lat1, double lon2, double lat2)
	Returns the angular separation of two locations on a sphere.
int	novas_set_catalog (cat_entry *restrict source, const char *restrict catalog, long num)
	Sets the optional catalog information for a sidereal source.
int	novas_set_current_time (int leap, double dut1, novas_timespec *restrict time)
	Sets the time eith the UNIX time obtained from the system clock.
int	novas_set_default_weather (on_surface *site)
	Sets default weather parameters based on an approximate global model to the mean annualized temperatures, based on Feulner et al.
int	novas_set_distance (cat_entry *source, double parsecs)
	Sets the distance for a catalog source.
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.
int	novas_set_orbsys_pole (enum novas_reference_system type, double ra, double dec, novas_orbital_system *restrict sys)
	Sets the orientation of an orbital system using the RA and DEC coordinates of the pole of the Laplace (or else equatorial) plane relative to which the orbital elements are defined.
int	novas_set_parallax (cat_entry *source, double mas)
	Sets the parallax (a measure of distance) for a catalog source.
int	novas_set_proper_motion (cat_entry *source, double pm_ra, double pm_dec)
	Sets the proper-motion for a (Galactic) catalog source.
int	novas_set_redshift (cat_entry *source, double z)
	Sets a redhift for a catalog source, as a relativistic measure of velocity.
int	novas_set_split_time (enum novas_timescale timescale, long ijd, double fjd, int leap, double dut1, novas_timespec *restrict time)
	Sets an astronomical time to the split Julian Date value, defined in the specified timescale.
int	novas_set_ssb_vel (cat_entry *source, double v_kms)
	Sets a radial velocity for a catalog source, defined w.r.t.
int	novas_set_str_time (enum novas_timescale timescale, const char *restrict str, int leap, double dut1, novas_timespec *restrict time)
	Sets astronomical time in a specific timescale using a string specification.
int	novas_set_time (enum novas_timescale timescale, double jd, int leap, double dut1, novas_timespec *restrict time)
	Sets an astronomical time to the fractional Julian Date value, defined in the specified timescale.
int	novas_set_unix_time (time_t unix_time, long nanos, int leap, double dut1, novas_timespec *restrict time)
	Sets an astronomical time to a UNIX time value.
double	novas_sets_below (double el, const object *restrict source, const novas_frame *restrict frame, RefractionModel ref_model)
	Returns the UTC date at which a distant source appears to set below the specified elevation angle.
int	novas_sky_pos (const object *restrict object, const novas_frame *restrict frame, enum novas_reference_system sys, sky_pos *restrict out)
	Calculates an apparent location on sky for the source.
double	novas_solar_illum (const object *restrict source, const novas_frame *restrict frame)
	Returns the Solar illumination fraction of a source, assuming a spherical geometry for the observed body.
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.
double	novas_ssb_to_lsr_vel (double epoch, double ra, double dec, double vLSR)
	Returns a radial-velocity referenced to the Local Standard of Rest (LSR) for a given Solar-System Barycentric (SSB) radial velocity.
double	novas_standard_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
	Returns an optical refraction correction for a standard atmosphere.
double	novas_str_degrees (const char *restrict dms)
	Returns an angle parsed from a string that contains either a decimal degrees or else a broken-down DMS representation.
double	novas_str_hours (const char *restrict hms)
	Returns a time or time-like angleparsed from a string that contains either a decimal hours or else a broken-down HMS representation.
double	novas_sun_angle (const object *restrict source, const novas_frame *restrict frame)
	Returns the apparent angular distance of a source from the Sun from the observer's point of view.
double	novas_time_gst (const novas_timespec *restrict time, enum novas_accuracy accuracy)
	Returns the Greenwich (apparent) Sidereal Time (GST/GaST) for a given astronomical time specification.
double	novas_time_lst (const novas_timespec *restrict time, double lon, enum novas_accuracy accuracy)
	Returns the Local (apparent) Sidereal Time (LST/LaST) for a given astronomical time specification and observer location.
enum novas_timescale	novas_timescale_for_string (const char *restrict str)
	Returns the timescale constant for a string that denotes the timescale in with a standard abbreviation (case insensitive).
int	novas_timestamp (const novas_timespec *restrict time, enum novas_timescale scale, char *restrict dst, int maxlen)
	Prints an astronomical timestamp to millisecond precision in the specified timescale to the specified string buffer.
long	novas_to_dexxx_planet (enum novas_planet id)
	Converts a NOVAS Solar-system body ID to a NAIF Solar-system body ID for DExxx ephemeris files.
long	novas_to_naif_planet (enum novas_planet id)
	Converts a NOVAS Solar-system body ID to a NAIF Solar-system body ID.
int	novas_track_pos (const novas_track *track, const novas_timespec *time, double *restrict lon, double *restrict lat, double *restrict dist, double *restrict z)
	Calculates a projected position, distance, and redshift for a source, given its near-term trajectory on sky, in the system for which the track was calculated.
int	novas_transform_sky_pos (const sky_pos *in, const novas_transform *restrict transform, sky_pos *out)
	Transforms a position or velocity 3-vector from one coordinate reference system to another.
int	novas_transform_vector (const double *in, const novas_transform *restrict transform, double *out)
	Transforms a position or velocity 3-vector from one coordinate reference system to another.
double	novas_transit_time (const object *restrict source, const novas_frame *restrict frame)
	Returns the UTC date at which a source transits the local meridian.
int	novas_uvw_to_xyz (const double *uvw, double ha, double dec, double *xyz)
	Converts equatorial u,v,w projected (absolute or relative) coordinates to rectangular telescope x,y,z coordinates (in ITRS) to for a specified line of sight.
double	novas_v2z (double vel)
	Converts a radial recession velocity to a redshift value (z = Δλ / λrest).
double	novas_wave_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
	The wavelength-dependent IAU atmospheric refraction model, based on the SOFA iauRefco() function, in compliance to the 'SOFA Software License' terms of the original source.
int	novas_xyz_to_los (const double *xyz, double lon, double lat, double *los)
	Converts a 3D rectangular equatorial (δx, δy, δz) vector to a polar (δφ, δθ δr) vector along a line-of-sight.
int	novas_xyz_to_uvw (const double *xyz, double ha, double dec, double *uvw)
	Converts rectangular telescope x,y,z (absolute or relative) coordinates (in ITRS) to equatorial u,v,w projected coordinates for a specified line of sight.
double	novas_z2v (double z)
	Converts a redshift value (z = Δλ / λrest) to a radial velocity (i.e.
double	novas_z_add (double z1, double z2)
	Compounds two redshift corrections, e.g.
double	novas_z_inv (double z)
	Returns the inverse of a redshift value, that is the redshift for a body moving with the same velocity as the original but in the opposite direction.
int	nu2000k (double jd_tt_high, double jd_tt_low, double *restrict dpsi, double *restrict deps)
	Computes the forced nutation of the non-rigid Earth: Model NU2000K.
int	nutation (double jd_tdb, enum novas_nutation_direction direction, enum novas_accuracy accuracy, const double *in, double *out)
	Nutates equatorial rectangular coordinates from mean equator and equinox of epoch to true equator and equinox of epoch.
int	nutation_angles (double t, enum novas_accuracy accuracy, double *restrict dpsi, double *restrict deps)
	Returns the IAU2000 / 2006 values for nutation in longitude and nutation in obliquity for a given TDB Julian date and the desired level of accuracy.
int	obs_planets (double jd_tdb, enum novas_accuracy accuracy, const double *restrict pos_obs, int pl_mask, novas_planet_bundle *restrict planets)
	Calculates the positions and velocities for the Solar-system bodies, e.g.
int	obs_posvel (double jd_tdb, double ut1_to_tt, enum novas_accuracy accuracy, const observer *restrict obs, const double *restrict geo_pos, const double *restrict geo_vel, double *restrict pos, double *restrict vel)
	Calculates the ICRS position and velocity of the observer relative to the Solar System Barycenter (SSB).
short	place (double jd_tt, const object *restrict source, const observer *restrict location, double ut1_to_tt, enum novas_reference_system coord_sys, enum novas_accuracy accuracy, sky_pos *restrict output)
	Computes the apparent direction of a celestial object at a specified time and in a specified coordinate system and for a given observer location.
int	place_cirs (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: CIRS observer location: geocenter position_type: apparent
int	place_gcrs (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: ICRS/GCRS observer location: geocenter position_type: apparent
int	place_icrs (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: ICRS / GCRS observer location: geocenter position_type: geometric
int	place_j2000 (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: J2000 observer location: geocenter position_type: apparent
int	place_mod (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: MOD observer location: geocenter position_type: apparent
int	place_star (double jd_tt, const cat_entry *restrict star, const observer *restrict obs, double ut1_to_tt, enum novas_reference_system system, enum novas_accuracy accuracy, sky_pos *restrict pos)
	Computes the apparent place of a star at the specified date, given its catalog mean place, proper motion, parallax, and radial velocity.
int	place_tod (double jd_tt, const object *restrict source, enum novas_accuracy accuracy, sky_pos *restrict pos)
	reference_system: TOD observer location: geocenter position_type: apparent
short	planet_ephem_provider (double jd_tdb, enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	Major planet ephemeris data via the same generic ephemeris provider that is configured by set_ephem_provider() prior to calling this routine.
short	planet_ephem_provider_hp (const double jd_tdb[restrict 2], enum novas_planet body, enum novas_origin origin, double *restrict position, double *restrict velocity)
	Major planet ephemeris data via the same generic ephemeris provider that is configured by set_ephem_provider() prior to calling this routine.
double	planet_lon (double t, enum novas_planet planet)
	Returns the planetary longitude, for Mercury through Neptune, w.r.t.
short	precession (double jd_tdb_in, const double *in, double jd_tdb_out, double *out)
	Precesses equatorial rectangular coordinates from one epoch to another using the IAU2006 (P03) precession model of Capitaine et al.
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.
int	rad_vel (const object *restrict source, const double *restrict pos_src, const double *vel_src, const double *vel_obs, double d_obs_geo, double d_obs_sun, double d_src_sun, double *restrict rv)
	Predicts the radial velocity of the observed object as it would be measured by spectroscopic means.
double	rad_vel2 (const object *restrict source, const double *pos_emit, const double *vel_src, const double *pos_det, const double *vel_obs, double d_obs_geo, double d_obs_sun, double d_src_sun)
	Predicts the radial velocity of the observed object as it would be measured by spectroscopic means.
int	radec2vector (double ra, double dec, double dist, double *restrict pos)
	Converts equatorial spherical coordinates to a vector (equatorial rectangular coordinates).
int	radec_planet (double jd_tt, const object *restrict ss_body, const observer *restrict obs, double ut1_to_tt, enum novas_reference_system sys, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis, double *restrict rv)
	Computes the place of a solar system body at the specified time for an observer in the specified coordinate system.
int	radec_star (double jd_tt, const cat_entry *restrict star, const observer *restrict obs, double ut1_to_tt, enum novas_reference_system sys, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict rv)
	Computes the place of a star at date 'jd_tt', for an observer in the specified coordinate system, given the star's ICRS catalog place, proper motion, parallax, and radial velocity.
double *	readeph (int mp, const char *restrict name, double jd_tdb, int *restrict error)
double	redshift_vrad (double vrad, double z)
	Applies an incremental redshift correction to a radial velocity.
double	refract (const on_surface *restrict location, enum novas_refraction_model model, double zd_obs)
	Computes atmospheric optical refraction for an observed (already refracted!) zenith distance through the atmosphere.
double	refract_astro (const on_surface *restrict location, enum novas_refraction_model model, double zd_astro)
	Computes atmospheric optical refraction for a source at an astrometric zenith distance (e.g.
int	set_cio_locator_file (const char *restrict filename)
int	set_ephem_provider (novas_ephem_provider func)
	Sets the function to use for obtaining position / velocity information for minor planets, or satellites.
int	set_nutation_lp_provider (novas_nutation_provider func)
	Set the function to use for low-precision IAU 2000 nutation calculations instead of the default nu2000k().
int	set_planet_provider (novas_planet_provider func)
	Set a custom function to use for regular precision (see NOVAS_REDUCED_ACCURACY) ephemeris calculations instead of the default solarsystem() routine.
int	set_planet_provider_hp (novas_planet_provider_hp func)
	Set a custom function to use for high precision (see NOVAS_FULL_ACCURACY) ephemeris calculations instead of the default solarsystem_hp() routine.
short	sidereal_time (double jd_ut1_high, double jd_ut1_low, double ut1_to_tt, enum novas_equinox_type gst_type, enum novas_earth_rotation_measure erot, enum novas_accuracy accuracy, double *restrict gst)
int	spin (double angle, const double *in, double *out)
	Transforms a vector from one coordinate system to another with same origin and axes rotated about the z-axis.
int	starvectors (const cat_entry *restrict star, double *restrict pos, double *restrict motion)
	Converts angular quantities for stars to vectors.
int	tdb2tt (double jd_tdb, double *restrict jd_tt, double *restrict secdiff)
	Computes the Terrestrial Time (TT) based Julian date corresponding to a Barycentric Dynamical Time (TDB) Julian date, and retuns th TDB-TT time difference also.
short	ter2cel (double jd_ut1_high, double jd_ut1_low, double ut1_to_tt, enum novas_earth_rotation_measure erot, enum novas_accuracy accuracy, enum novas_equatorial_class coordType, double xp, double yp, const double *in, double *out)
int	terra (const on_surface *restrict location, double gast, double *restrict pos, double *restrict vel)
	Computes the position and velocity vectors of a terrestrial observer with respect to the center of the Earth, based on the GRS80 reference ellipsoid, used for the International Terrestrial Reference Frame (ITRF) and its realizations.
int	tod_to_cirs (double jd_tt, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from the True of Date (TOD) reference system to the Celestial Intermediate Reference System (CIRS) at the given epoch to the .
int	tod_to_gcrs (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from True of Date (TOD) reference frame at the given epoch to the ICRS / GCRS.
int	tod_to_itrs (double jd_tt_high, double jd_tt_low, double ut1_to_tt, enum novas_accuracy accuracy, double xp, double yp, const double *in, double *out)
	Rotates a position vector from the dynamical True of Date (TOD) frame of date the Earth-fixed ITRS frame (pre IAU 2000 method).
int	tod_to_j2000 (double jd_tdb, enum novas_accuracy accuracy, const double *in, double *out)
	Transforms a rectangular equatorial (x, y, z) vector from True of Date (TOD) reference frame at the given epoch to the J2000 coordinates.
short	topo_planet (double jd_tt, const object *restrict ss_body, double ut1_to_tt, const on_surface *restrict position, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis)
	reference_system: TOD observer location: topocentric (on Earth) position_type: apparent
short	topo_star (double jd_tt, double ut1_to_tt, const cat_entry *restrict star, const on_surface *restrict position, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec)
	reference_system: TOD observer location: topocentric (on Earth) position_type: apparent
short	transform_cat (enum novas_transform_type, 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.
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.
double	tt2tdb (double jd_tt)
	Returns the TDB - TT time difference in seconds for a given TT or TDB date, with a maximum error of 10 μs for dates between 1600 and 2200.
double	tt2tdb_fp (double jd_tt, double limit)
	Returns the TDB-TT time difference with flexible precision.
double	tt2tdb_hp (double jd_tt)
	Returns the TDB-TT time difference with high precision.
double	unredshift_vrad (double vrad, double z)
	Undoes an incremental redshift correction that was applied to radial velocity.
short	vector2radec (const double *restrict pos, double *restrict ra, double *restrict dec)
	Converts an vector in equatorial rectangular coordinates to equatorial spherical coordinates.
short	virtual_planet (double jd_tt, const object *restrict ss_body, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec, double *restrict dis)
	reference_system: ICRS / GCRS observer location: geocenter position_type: apparent
short	virtual_star (double jd_tt, const cat_entry *restrict star, enum novas_accuracy accuracy, double *restrict ra, double *restrict dec)
	reference_system: ICRS / GCRS observer location: geocenter position_type: apparent
int	wobble (double jd_tt, enum novas_wobble_direction direction, double xp, double yp, const double *in, double *out)
	Corrects a vector in the ITRS (rotating Earth-fixed system) for polar motion, and also corrects the longitude origin (by a tiny amount) to the Terrestrial Intermediate Origin (TIO).

Variables
int	grav_bodies_full_accuracy
	Current set of gravitating bodies to use for deflection calculations in full accuracy mode.
int	grav_bodies_reduced_accuracy
	Current set of gravitating bodies to use for deflection calculations in reduced accuracy mode.

Detailed Description

SuperNOVAS types, definitions, and function prototypes.

SuperNOVAS astrometry software based on the Naval Observatory Vector Astrometry Software (NOVAS). It has been modified to fix outstanding issues, make it easier to use, and provide a ton of new features.

Based on the NOVAS C Edition, Version 3.1:

U. S. Naval Observatory
Astronomical Applications Dept.
Washington, DC
http://www.usno.navy.mil/USNO/astronomical-applications

Author

G. Kaplan and Attila Kovacs

Version

1.5.0

Macro Definition Documentation

BARYC

#define BARYC   NOVAS_BARYCENTER

Deprecated.

Deprecated

Old definition of the Barycenter origin. NOVAS_BARYCENTER is preferred.

HELIOC

#define HELIOC   NOVAS_HELIOCENTER

Deprecated.

Deprecated

Old definition of the Center of Sun as the origin. NOVAS_HELIOCENTER is preferred.

NOVAS_DELAUNAY_ARGS_INIT

#define NOVAS_DELAUNAY_ARGS_INIT

Empty initializer for novas_delaunay_args.

Since

1.3

Author

Attila Kovacs

See also

novas_delaunay_args

NOVAS_EQUATOR_TYPES

#define NOVAS_EQUATOR_TYPES   (NOVAS_GCRS_EQUATOR + 1)

The number of equator types defined in enum novas_equator_type.

See also

enum novas_equator_type

Since

1.2

NOVAS_MATRIX_IDENTITY

#define NOVAS_MATRIX_IDENTITY

novas_matric initializer for an indentity matrix

Since

1.3

See also

novas_matrix, NOVAS_MATRIX_INIT

NOVAS_MATRIX_INIT

#define NOVAS_MATRIX_INIT

Empty initializer for novas_matrix.

Since

1.3

See also

novas_matrix, NOVAS_MATRIX_IDENTITY

NOVAS_OBJECT_TYPES

#define NOVAS_OBJECT_TYPES   (NOVAS_ORBITAL_OBJECT + 1)

The number of object types distinguished by NOVAS.

See also

enum novas_object_type

NOVAS_OBSERVER_PLACES

#define NOVAS_OBSERVER_PLACES   (NOVAS_SOLAR_SYSTEM_OBSERVER + 1)

The number of observer place types supported.

See also

enum novas_observer_place

NOVAS_ORIGIN_TYPES

#define NOVAS_ORIGIN_TYPES   (NOVAS_HELIOCENTER + 1)

The number of different ICSR origins available in NOVAS.

See also

enum novas_origin

NOVAS_PLANET_BUNDLE_INIT

#define NOVAS_PLANET_BUNDLE_INIT

Empty initializer for novas_planet_bundle.

Since

1.3

See also

novas_planet_bundle

NOVAS_PLANET_GRAV_Z_INIT

#define NOVAS_PLANET_GRAV_Z_INIT

Gravitational redshifts for major planets (and Moon and Sun) for light emitted at surface and detected at a large distance away.

Barycenters are not considered, and for Pluto the redshift for the Pluto system is assumed for distant observers.

See also

enum novas_planet

NOVAS_PLANETS

Since

1.1.1

Author

Attila Kovacs

NOVAS_PLANET_INIT

#define NOVAS_PLANET_INIT	(		num,
			name )

object initializer macro for major planets, the Sun, Moon, and barycenters.

Parameters

num	An enum novas_planet number
name	The designated planet name

Since

1.2

See also

object, make_planet()

NOVAS_PLANET_RADII_INIT

#define NOVAS_PLANET_RADII_INIT

Array initializer for mean planet radii in meters, matching the enum novas_planet.

E.g.

const double *planet_radii[] = NOVAS_PLANET_RADII_INIT;

REFERENCES:

1. https://orbital-mechanics.space/reference/planetary-parameters.html, Table 3.
2. B. A. Archinal, et al., Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements:
   1. Celestial Mechanics and Dynamical Astronomy, 130(3):22, March 2018. doi:10.1007/s10569-017-9805-5.
3. B. A. Archinal, et al., Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements:
   1. Celestial Mechanics and Dynamical Astronomy, 130(3):22, March 2018. doi:10.1007/s10569-017-9805-5.

Since

1.5

Author

Attila Kovacs

See also

enum novas_planet, NOVAS_PLANET_NAMES_INIT, NOVAS_RMASS_INIT

NOVAS_PLANETS

#define NOVAS_PLANETS   (NOVAS_PLUTO_BARYCENTER + 1)

The number of major planets defined in NOVAS.

See also

enum novas_planet

NOVAS_REFERENCE_SYSTEMS

#define NOVAS_REFERENCE_SYSTEMS   (NOVAS_ITRS + 1)

The number of basic coordinate reference systems in NOVAS.

See also

enum novas_reference_system

NOVAS_REFRACTION_MODELS

#define NOVAS_REFRACTION_MODELS   (NOVAS_WAVE_REFRACTION + 1)

The number of built-in refraction models available in SuperNOVAS.

See also

enum novas_refraction_model

NOVAS_RMASS_INIT

#define NOVAS_RMASS_INIT

Reciprocal masses of solar system bodies, from DE-405 (Sun mass / body mass).

[0]: Earth/Moon barycenter (legacy from NOVAS C), MASS[1] = Mercury, ...,

Barycentric reciprocal masses (index 12, 13) are not set.

NOTES:

1. The values have been updated to used DE440 data (Park et al. 2021) in 1.4.

REFERENCES:

1. Ryan S. Park et al 2021 AJ 161 105, DOI 10.3847/1538-3881/abd414
2. IERS Conventions, Chapter 3, Table 3.1

Since

1.2

Author

Attila Kovacs

See also

enum novas_planet, NOVAS_PLANET_NAMES_INIT, NOVAS_PLANET_RAII_INIT, NOVAS_PLANETS_GRAV_Z_INIT

NOVAS_SOLAR_CONSTANT

#define NOVAS_SOLAR_CONSTANT   1367.0

[W/m²] The Solar Constant i.e., typical incident Solar power on Earth.

The value of 1367 Wm⁻² was adopted by the World Radiation Center (Gueymard, 2004).

Since

1.3

See also

novas_solar_power()

NOVAS_SOLAR_RADIUS

#define NOVAS_SOLAR_RADIUS   696340000.0

[m] Solar radius (photosphere)

Since

1.1

NOVAS_TIMESCALES

#define NOVAS_TIMESCALES   (NOVAS_UT1 + 1)

The number of asronomical time scales supported.

Since

1.1

See also

novas_timescale

NOVAS_TRANSFORM_TYPES

#define NOVAS_TRANSFORM_TYPES   (ICRS_TO_J2000 + 1)

The number of coordinate transfor types in NOVAS.

See also

enum novas_transform_type

NOVAS_WOBBLE_DIRECTIONS

#define NOVAS_WOBBLE_DIRECTIONS   (WOBBLE_PEF_TO_ITRS + 1)

Number of values in enum novas_wobble_direction.

Since

1.4

See also

novas_wobble_direction

Enumeration Type Documentation

novas_cio_location_type

enum novas_cio_location_type

Deprecated

This enum is used only by functions which have been deprecated. Hence you probably won't need this either.

System in which CIO location is calculated.

Enumerator
CIO_VS_GCRS	The location of the CIO relative to the GCRS frame.
CIO_VS_EQUINOX	The location of the CIO relative to the true equinox in the dynamical frame.

novas_earth_rotation_measure

enum novas_earth_rotation_measure

Deprecated

This enum is used only by functions which have been deprecated. Hence you probably won't need this either.

Constants that determine the type of rotation measure to use.

Enumerator
EROT_ERA	Use Earth Rotation Angle (ERA) as the rotation measure, relative to the CIO (new IAU 2006 standard)
EROT_GST	Use GST as the rotation measure, relative to the true equinox (pre IAU 20006 standard)

novas_equatorial_class

enum novas_equatorial_class

Deprecated

This enum is used only by functions which have been deprecated. Hence you probably won't need this either.

The class of celestial coordinates used as parameters for ter2cel() and cel2ter().

Enumerator
NOVAS_REFERENCE_CLASS	Celestial coordinates are in GCRS.
NOVAS_DYNAMICAL_CLASS	Celestial coordinates are apparent values (CIRS or TOD)

novas_pole_offset_type

enum novas_pole_offset_type

Deprecated

This enum is used only by functions which have been deprecated. Hence you probably won't need this either.

The convention in which the celestial pole offsets are defined for polar wobble.

Enumerator
POLE_OFFSETS_DPSI_DEPS	Offsets are Δdψ, Δdε pairs (pre IAU 2006 precession-nutation model).
POLE_OFFSETS_X_Y	Offsets are dx, dy pairs (IAU 2006 precession-nutation model)

Function Documentation

aberration()

int aberration	(	const double *	pos,
		const double *	vobs,
		double	lighttime,
		double *	out )

Corrects position vector for aberration of light.

Algorithm includes relativistic terms.

NOTES:

1. This function is called by place() to account for aberration when calculating the position of the source.

REFERENCES:

1. Murray, C. A. (1981) Mon. Notices Royal Ast. Society 195, 639-648.
2. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.

Parameters

	pos	[AU] Position vector of source relative to observer
	vobs	[AU/day] Velocity vector of observer, relative to the solar system barycenter.
	lighttime	[day] Light time from object to Earth (if known). Or set to 0, and this function will compute it as needed.
[out]	out	[AU] Position vector, referred to origin at center of mass of the Earth, corrected for aberration. It can be the same vector as one of the inputs.

Returns

0 if successful, or -1 if any of the vector arguments are NULL.

See also

frame_aberration()

References novas_vlen().

bary2obs()

int bary2obs	(	const double *	pos,
		const double *	pos_obs,
		double *	out,
		double *restrict	lighttime )

Moves the origin of coordinates from the barycenter of the solar system to the observer (or the geocenter); i.e., this function accounts for parallax (annual+geocentric or just annual).

REFERENCES:

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

Parameters

	pos	[AU] Position vector, referred to origin at solar system barycenter.
	pos_obs	[AU] Position vector of observer (or the geocenter), with respect to origin at solar system barycenter.
[out]	out	[AU] Position vector, referred to origin at center of mass of the Earth. It may be NULL if not required, or be the same vector as either of the inputs.
[out]	lighttime	[day] Light time from object to Earth. It may be NULL if not required.

Returns

0 if successful, or -1 if any of the essential pointer arguments is NULL.

See also

novas_make_frame(), light_time2()

References novas_vlen().

cel2ter()

short cel2ter	(	double	jd_ut1_high,
		double	jd_ut1_low,
		double	ut1_to_tt,
		enum novas_earth_rotation_measure	erot,
		enum novas_accuracy	accuracy,
		enum novas_equatorial_class	coordType,
		double	xp,
		double	yp,
		const double *	in,
		double *	out )

Deprecated

This function can be confusing to use due to the input coordinate system being specified by a combination of two options. Use itrs_to_cirs() or itrs_to_tod() instead. You can then follow these with other conversions to GCRS (or whatever else) as appropriate.

Rotates a vector from the celestial to the terrestrial system. Specifically, it transforms a vector in the GCRS, or the dynamical (CIRS or TOD) frames to the ITRS (a rotating Earth-fixed system) by applying rotations for the GCRS-to-dynamical frame tie, precession, nutation, Earth rotation, and polar motion.

If 'system' is NOVAS_CIRS then method EROT_ERA must be used. Similarly, if 'system' is NOVAS_TOD then method must be EROT_ERA. Otherwise an error 3 is returned.

If both 'xp' and 'yp' are set to 0 no polar motion is included in the transformation.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Kaplan, G. H. (2003), 'Another Look at Non-Rotating Origins', Proceedings of IAU XXV Joint Discussion 16.

Parameters

	jd_ut1_high	[day] High-order part of UT1 Julian date.
	jd_ut1_low	[day] Low-order part of UT1 Julian date.
	ut1_to_tt	[s] TT - UT1 Time difference in seconds
	erot	Unused.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
	coordType	Input coordinate class, NOVAS_REFERENCE_CLASS (0) or NOVAS_DYNAMICAL_CLASS (1). Use the former if the input coordinates are in the GCRS, and the latter if they are CIRS or TOD (the 'erot' parameter selects which dynamical system the input is specified in.)
	xp	[arcsec] Conventionally-defined X coordinate of celestial intermediate pole with respect to ITRS pole. If you have defined pole offsets the old (pre IAU2000) way, via cel_pole(), then use 0 here.
	yp	[arcsec] Conventionally-defined Y coordinate of celestial intermediate pole with respect to ITRS pole. If you have defined pole offsets the old (pre IAU2000) way, via cel_pole(), then use 0 here.
	in	Input position vector, geocentric equatorial rectangular coordinates in the specified input coordinate system (GCRS if 'class' is NOVAS_REFERENCE_CLASS; or else either CIRS if 'erot' is EROT_ERA, or TOD if 'erot' is EROT_GST).
[out]	out	ITRS position vector, geocentric equatorial rectangular coordinates (terrestrial system). It can be the same vector as the input.

Returns

0 if successful, -1 if either of the vector arguments is NULL, 1 if 'accuracy' is invalid, 2 if 'method' is invalid, or else 10 + the error from cio_location(), or 20 + error from cio_basis().

See also

novas_app_to_hor(), gcrs_to_cirs(), cirs_to_itrs(), frame_tie(), j2000_to_tod(), tod_to_itrs(), ter2cel()

References era(), EROT_ERA, EROT_GST, gcrs_to_cirs(), gcrs_to_tod(), NOVAS_DYNAMICAL_CLASS, NOVAS_FULL_ACCURACY, novas_gast(), NOVAS_REDUCED_ACCURACY, spin(), wobble(), WOBBLE_PEF_TO_ITRS, and WOBBLE_TIRS_TO_ITRS.

cel_pole()

short cel_pole	(	double	jd_tt,
		enum novas_pole_offset_type	type,
		double	dpole1,
		double	dpole2 )

Deprecated

This old way of incorporating Earth orientation parameters into the true equator and equinox is now disfavored. Instead, the pole offsets should be used only to convert between the Terrestrial Intermediate Reference System (TIRS) / Pseudo Earth Fixed (PEF) and the International Terrestrial Reference System (ITRS) going forward, e.g. via novas_app_to_hor() / novas_hor_to_app() or else wobble().

Specifies the unmodeled celestial pole offsets for high-precision applications to be applied to the True of Date (TOD) equator, in the old, pre IAU 2006 methodology. Nonetheless, these offsets should be specified relative to the IAU2006 precession / nutation model to provide a correction to the modeled (precessed and nutated) position of Earth's pole, such those derived from observations and published by IERS.

The call sets the global variables PSI_COR and EPS_COR, for subsequent calls to e_tilt(). As such, it should be called to specify pole offsets prior to legacy NOVAS C equinox-specific calls. The global values of PSI_COR and EPS_COR specified via this function will be effective until explicitly changed again.

NOTES:

1. The pole offsets et this way will affect all future TOD-based calculations, until the pole is changed or reset again. Hence, you should be extremely careful using it (if at all), as it may become an unpredictable source of inaccuracy if implicitly applied without intent to do so.
2. The current UT1 - UTC time difference, and polar offsets, historical data and near-term projections are published in the <a href="https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html>IERS Bulletins
3. If Δδψ, Δδdε offsets are specified, these must be the residual corrections relative to the IAU 2006 precession/nutation model (not the Lieske et al. 1977 model!). As such, they are just a rotated version of the newer x_p, y_p offsets published by IERS.
4. The equivalent IAU 2006 standard method, which is preferred, is to apply x_p, y_p pole offsets only for converting between TIRS and ITRS, e.g. via novas_app_to_hor(),novas_hor_to_app(), or wobble()).
5. There is no need to define pole offsets this way when using the newer frame-based approach introduced in SuperNOVAS. If the pole offsets are specified on a per-frame basis during the initialization of each observing frame (see novas_make_frame(), the offsets will be applied for the TIRS / ITRS conversion only, and not to the TOD equator per se.

REFERENCES:

1. Kaplan, G. (2005), US Naval Observatory Circular 179.
2. Kaplan, G. (2003), USNO/AA Technical Note 2003-03.

Parameters

jd_tt	[day] Terrestrial Time (TT) based Julian date. Used only if 'type' is POLE_OFFSETS_X_Y (2), to transform dx and dy to the equivalent Δδψ and Δδε values.
type	POLE_OFFSETS_DPSI_DEPS (1) if the offsets are Δδψ, Δδε relative to the IAU 20006 precession/nutation model; or POLE_OFFSETS_X_Y (2) if they are dx, dy offsets relative to the IAU 2000 / 2006 precession-nutation model.
dpole1	[mas] Value of celestial pole offset in first coordinate, (Δδψ for or dx) in milliarcseconds, relative to the IAU2006 precession/nutation model.
dpole2	[mas] Value of celestial pole offset in second coordinate, (Δδε or dy) in milliarcseconds, relative to the IAU2006 precession/nutation model.

Returns

0 if successful, or else 1 if 'type' is invalid.

See also

novas_make_frame(), wobble()

References POLE_OFFSETS_DPSI_DEPS, and POLE_OFFSETS_X_Y.

cio_array()

short cio_array	(	double	jd_tdb,
		long	n_pts,
		ra_of_cio *restrict	cio )

Deprecated

This function is no longer used within SuperNOVAS. It is still provided, however, in order to retain 100% API compatibility with NOVAS C.

Given an input TDB Julian date and the number of data points desired, this function returns a set of Julian dates and corresponding values of the GCRS right ascension of the celestial intermediate origin (CIO). The range of dates is centered on the requested date.

NOTES:

1. This function has been completely re-written by A. Kovacs to provide much more efficient caching and I/O.

2. The CIO locator file that is bundled was prepared with the original IAU2000A nutation model, not with the newer R06 (a.k.a. IAU2006) nutation model, resulting in an error up to the few tens of micro-arcseconds level for dates between 1900 and 2100, and larger errors further away from the current epoch.

3. Prior to version 1.5, this function relied on a CIO locator file (CIO_RA.TXT or cio_ra.bin). The current version no longer does, and instead generates the requested data on the fly.

Parameters

	jd_tdb	[day] Barycentric Dynamic Time (TDB) based Julian date
	n_pts	Number of Julian dates and right ascension values requested (not less than 2 or more than NOVAS_CIO_CACHE_SIZE).
[out]	cio	A time series (array) of the right ascension of the Celestial Intermediate Origin (CIO) with respect to the GCRS.

Returns

0 if successful, -1 if the output array is NULL or there was an I/O error accessing the CIO location data file. Or else 1 if no locator data file is available, 2 if 'jd_tdb' not in the range of the CIO file, 3 if 'n_pts' out of range, or 6 if 'jd_tdb' is too close to either end of the CIO file do we are unable to put 'n_pts' data points into the output

See also

set_cio_locator_file(), cio_location()

References ra_of_cio::jd_tdb, NOVAS_ARCSEC, NOVAS_HOURANGLE, and ra_of_cio::ra_cio.

cio_basis()

short cio_basis	(	double	jd_tdb,
		double	ra_cio,
		enum novas_cio_location_type	loc_type,
		enum novas_accuracy	accuracy,
		double *restrict	x,
		double *restrict	y,
		double *restrict	z )

Deprecated

This function is no longer used internally in the library, and users are recommended against using it themselves, since SuperNOVAS provides better ways to convert between GCRS and CIRS using frames or via gcrs_to_cirs() / cirs_to_gcrs() or novas_transform() functions.

Computes the CIRS basis vectors, with respect to the GCRS (geocentric ICRS), of the celestial intermediate system defined by the celestial intermediate pole (CIP) (in the z direction) and the celestial intermediate origin (CIO) (in the x direction).

This function effectively constructs the CIRS to GCRS transformation matrix C in eq. (3) of the reference.

NOTES:

1. This function caches the results of the last calculation in case it may be re-used at no extra computational cost for the next call.

REFERENCES:

1. Kaplan, G. (2005), US Naval Observatory Circular 179.

Parameters

	jd_tdb	[day] Barycentric Dynamic Time (TDB) based Julian date
	ra_cio	[h] Right ascension of the CIO at epoch (hours).
	loc_type	CIO_VS_GCRS (1) if the cio location is relative to the GCRS or else CIO_VS_EQUINOX (2) if relative to the true equinox of date.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	x	Unit 3-vector toward the CIO, equatorial rectangular coordinates, referred to the GCRS.
[out]	y	Unit 3-vector toward the y-direction, equatorial rectangular coordinates, referred to the GCRS.
[out]	z	Unit 3-vector toward north celestial pole (CIP), equatorial rectangular coordinates, referred to the GCRS.

Returns

0 if successful, or -1 if any of the output vector arguments are NULL or if the accuracy is invalid, or else 1 if 'ref-sys' is invalid.

See also

gcrs_to_cirs(), cirs_to_gcrs(), novas_make_transform()

References CIO_VS_EQUINOX, CIO_VS_GCRS, NOVAS_FULL_ACCURACY, NOVAS_REDUCED_ACCURACY, novas_vlen(), and tod_to_gcrs().

cio_location()

short cio_location	(	double	jd_tdb,
		enum novas_accuracy	accuracy,
		double *restrict	ra_cio,
		short *restrict	loc_type )

Deprecated

This function is no longer used internally in the library. Given that the CIO is defined on the dynamical equator of date, it is not normally meaningful to provide an R.A. coordinate for it in GCRS. Instead, you might use cio_ra() to get the CIO location w.r.t. the equinox of date (on the same dynamical equator), or equivalently ira_equinox() to return the negated value of the same.

Returns the location of the celestial intermediate origin (CIO) for a given Julian date, as a right ascension with respect to the true equinox of date. The CIO is always located on the true equator (= intermediate equator) of date.

NOTES:

1. Unlike the NOVAS C version of this function, this version will always return a CIO location as long as the pointer arguments are not NULL.
2. This function caches the results of the last calculation in case it may be re-used at no extra computational cost for the next call.
3. As of version 1.5, this function always returns the CIO location w.r.t. the true equinox of date, on the true equator of date, i.e. the R.A. of the CIO on the true equator of date, meaured from the true equinox of date.

Parameters

	jd_tdb	[day] Barycentric Dynamic Time (TDB) based Julian date
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra_cio	[h] Right ascension of the CIO, in hours, or NAN if returning with an error.
[out]	loc_type	Pointer in which to return the reference system in which right ascension is given, which is either CIO_VS_GCRS (1) if the location was obtained via interpolation of the available data file, or else CIO_VS_EQUINOX (2) if it was calculated locally. It is set to -1 if returning with an error.

Returns

0 if successful, -1 if one of the pointer arguments is NULL or the accuracy is invalid.

See also

cio_ra(), ira_equinox()

References CIO_VS_EQUINOX, ira_equinox(), NOVAS_FULL_ACCURACY, NOVAS_REDUCED_ACCURACY, and NOVAS_TRUE_EQUINOX.

d_light()

double d_light	(	const double *	pos_src,
		const double *	pos_body )

Returns the difference in light-time, for a star, between the barycenter of the solar system and the observer (or the geocenter) (Usage A).

Alternatively (Usage B), this function returns the light-time from the observer (or the geocenter) to a point on a light ray that is closest to a specific solar system body. For this purpose, 'pos_src' is the position vector toward observed object, with respect to origin at observer (or the geocenter); 'pos_body' is the position vector of solar system body, with respect to origin at observer (or the geocenter), components in AU; and the returned value is the light time to point on line defined by 'pos' that is closest to solar system body (positive if light passes body before hitting observer, i.e., if 'pos_body' is within 90 degrees of 'pos_src').

NOTES:

1. This function is called by novas_geom_posvel(), novas_sky_pos(), or place()

Parameters

pos_src	Position vector towards observed object, with respect to the SSB (Usage A), or relative to the observer / geocenter (Usage B).
pos_body	[AU] Position of observer relative to SSB (Usage A), or position of intermediate solar-system body with respect to the observer / geocenter (Usage B).

Returns

[day] Difference in light time to observer, either relative to SSB (Usage A) or relative intermediate solar-system body (Usage B); or else NAN if either of the input arguments is NULL.

See also

novas_sky_pos(), novas_geom_posvel()

References novas_vlen().

equ2hor()

int equ2hor	(	double	jd_ut1,
		double	ut1_to_tt,
		enum novas_accuracy	accuracy,
		double	xp,
		double	yp,
		const on_surface *restrict	location,
		double	ra,
		double	dec,
		enum novas_refraction_model	ref_option,
		double *restrict	zd,
		double *restrict	az,
		double *restrict	rar,
		double *restrict	decr )

Deprecated

You should use the frame-based novas_app_to_hor() instead, or else the more explicit (less ambiguous) tod_to_itrs() followed by itrs_to_hor(), and possibly following it with an atmospheric refraction correction if appropriate.

Transforms topocentric (TOD) apparent right ascension and declination to zenith distance and azimuth. This method should not be used to convert CIRS apparent coordinates (IAU 2000 standard) – for those you should use cirs_to_itrs() followed by itrs_to_hor() instead.

It uses a method that properly accounts for polar motion, which is significant at the sub-arcsecond level. This function can also adjust coordinates for atmospheric refraction.

NOTES:

• 'xp' and 'yp' can be set to zero if sub-arcsecond accuracy is not needed.
• The directions 'zd'= 0 (zenith) and 'az'= 0 (north) are here considered fixed in the terrestrial system. Specifically, the zenith is along the geodetic normal, and north is toward the ITRS pole.
• If 'ref_option' is NOVAS_STANDARD_ATMOSPHERE (1), then 'rar'='ra' and 'decr'='dec'.

REFERENCES:

1. Kaplan, G. (2008). USNO/AA Technical Note of 28 Apr 2008, "Refraction as a Vector."

Parameters

	jd_ut1	[day] UT1 based Julian date
	ut1_to_tt	[s] TT - UT1 Time difference in seconds
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
	xp	[arcsec] Conventionally-defined x coordinate of celestial intermediate pole with respect to ITRS reference pole, e.g. from IERS Bulletin A. If you have defined pole offsets to be incorporated into the TOD input coordinates (pre-IAU2000 method) via cel_pole(), then you should set this to 0.
	yp	[arcsec] Conventionally-defined y coordinate of celestial intermediate pole with respect to ITRS reference pole, e.g. from IERS Bulletin A. If you have defined pole offsets to be incorporated into the TOD input coordinates (pre-IAU2000 method) via cel_pole(), then you should set this to 0.
	location	Geodetic (ITRF / GRS80) observer location on Earth
	ra	[h] Topocentric apparent (TOD) right ascension of object of interest, referred to true equator and equinox of date.
	dec	[deg] Topocentric apparent (TOD) declination of object of interest, referred to true equator and equinox of date.
	ref_option	Refraction model to use. E.g., NOVAS_STANDARD_ATMOSPHERE (1), or NOVAS_WEATHER_AT_LOCATION (2) if to use the weather.
[out]	zd	[deg] Topocentric zenith distance in degrees (unrefracted).
[out]	az	[deg] Topocentric azimuth (measured east from north) in degrees.
[out]	rar	[h] Topocentric right ascension of object of interest, in hours, referred to true equator and equinox of date, affected by refraction if 'ref_option' is non-zero. (It may be NULL if not required)
[out]	decr	[deg] Topocentric declination of object of interest, in degrees, referred to true equator and equinox of date. (It may be NULL if not required)

Returns

0 if successful, or -1 if one of the 'zd' or 'az' output pointers are NULL.

See also

itrs_to_hor(), tod_to_itrs(), NOVAS_TOD

References EROT_GST, NOVAS_DYNAMICAL_CLASS, refract_astro(), and ter2cel().

grav_def()

short grav_def	(	double	jd_tdb,
		enum novas_observer_place	unused,
		enum novas_accuracy	accuracy,
		const double *	pos_src,
		const double *	pos_obs,
		double *	out )

(primarily for internal use) Computes the total gravitational deflection of light for the observed object due to the major gravitating bodies in the solar system.

This function valid for an observed body within the solar system as well as for a star.

If 'accuracy' is NOVAS_FULL_ACCURACY (0), the deflections due to the Sun, Jupiter, Saturn, and Earth are calculated. Otherwise, only the deflection due to the Sun is calculated. In either case, deflection for a given body is ignored if the observer is within ~1500 km of the center of the gravitating body.

The number of bodies used at full and reduced accuracy can be set by changing the grav_bodies_reduced_accuracy, and grav_bodies_full_accuracy lobal variables.

NOTES:

1. This function is called by novas_sky_pos() novas_app_to_geom(),novas_geom_to_app() andplace()` to calculate gravitational deflections as appropriate for positioning sources precisely. The gravitational deflection due to planets requires a planet calculator function to be configured, e.g. via set_planet_provider_hp().

REFERENCES:

1. Klioner, S. (2003), Astronomical Journal 125, 1580-1597, Section 6.

Parameters

	jd_tdb	[day] Barycentric Dynamical Time (TDB) based Julian date
	unused	The type of observer frame (no longer used)
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1). In full accuracy mode, it will calculate the deflection due to the Sun, Jupiter, Saturn and Earth. In reduced accuracy mode, only the deflection due to the Sun is calculated.
	pos_src	[AU] Position 3-vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, components in AU.
	pos_obs	[AU] Position 3-vector of observer (or the geocenter), with respect to origin at solar system barycenter, referred to ICRS axes, components in AU.
[out]	out	[AU] Position vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, corrected for gravitational deflection, components in AU. It can be the same vector as the input, but not the same as pos_obs.

Returns

0 if successful, -1 if any of the pointer arguments is NULL or if the output vector is the same as pos_obs, or the error from obs_planets().

See also

grav_undef()

novas_sky_pos(), novas_geom_to_app(), novas_app_to_geom(), set_planet_provider_hp(), grav_bodies_full_accuracy, grav_bodies_reduced_accuracy

References grav_bodies_full_accuracy, grav_bodies_reduced_accuracy, grav_planets(), NOVAS_FULL_ACCURACY, and obs_planets().

grav_planets()

int grav_planets	(	const double *	pos_src,
		const double *	pos_obs,
		const novas_planet_bundle *restrict	planets,
		double *	out )

(primarily for internal use) Computes the total gravitational deflection of light for the observed object due to the specified gravitating bodies in the solar system.

This function is valid for an observed body within the solar system as well as for a star.

NOTES:

1. The gravitational deflection due to planets requires a planet calculator function to be configured, e.g. via set_planet_provider_hp().

REFERENCES:

1. Klioner, S. (2003), Astronomical Journal 125, 1580-1597, Section 6.

Parameters

	pos_src	[AU] Position 3-vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, components in AU.
	pos_obs	[AU] Position 3-vector of observer (or the geocenter), with respect to origin at solar system barycenter, referred to ICRS axes, components in AU.
	planets	Apparent planet data containing positions and velocities for the major gravitating bodies in the solar-system.
[out]	out	[AU] Position vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, corrected for gravitational deflection, components in AU. It can be the same vector as the input, but not the same as pos_obs.

Returns

0 if successful, -1 if any of the pointer arguments is NULL or if the output vector is the same as pos_obs.

See also

grav_def(), grav_undo_planets()

novas_sky_pos(), novas_geom_to_app(), obs_planets()

Since

1.1

Author

Attila Kovacs

References d_light(), grav_vec(), NOVAS_PLANETS, NOVAS_RMASS_INIT, and novas_vlen().

grav_undef()

int grav_undef	(	double	jd_tdb,
		enum novas_accuracy	accuracy,
		const double *	pos_app,
		const double *	pos_obs,
		double *	out )

(primarily for internal use) Computes the gravitationally undeflected position of an observed source position due to the major gravitating bodies in the solar system.

This function is valid for an observed body within the solar system as well as for a star.

If 'accuracy' is set to zero (full accuracy), three bodies (Sun, Jupiter, and Saturn) are used in the calculation. If the reduced-accuracy option is set, only the Sun is used in the calculation. In both cases, if the observer is not at the geocenter, the deflection due to the Earth is included.

he number of bodies used at full and reduced accuracy can be set by changing the grav_bodies_reduced_accuracy, and grav_bodies_full_accuracy lobal variables.

REFERENCES:

1. Klioner, S. (2003), Astronomical Journal 125, 1580-1597, Section 6.

Parameters

	jd_tdb	[day] Barycentric Dynamical Time (TDB) based Julian date
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
	pos_app	[AU] Apparent position 3-vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, components in AU.
	pos_obs	[AU] Position 3-vector of observer (or the geocenter), with respect to origin at solar system barycenter, referred to ICRS axes, components in AU.
[out]	out	[AU] Nominal position vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, without gravitational deflection, components in AU. It can be the same vector as the input, but not the same as pos_obs.

Returns

0 if successful, -1 if any of the pointer arguments is NULL (errno = EINVAL) or if the result did not converge (errno = ECANCELED), or else an error from obs_planets().

See also

grav_def()

novas_app_to_geom(), set_planet_provider_hp(), grav_bodies_full_accuracy, grav_bodies_reduced_accuracy

Since

1.1

Author

Attila Kovacs

References grav_bodies_full_accuracy, grav_bodies_reduced_accuracy, grav_undo_planets(), NOVAS_FULL_ACCURACY, and obs_planets().

grav_undo_planets()

int grav_undo_planets	(	const double *	pos_app,
		const double *	pos_obs,
		const novas_planet_bundle *restrict	planets,
		double *	out )

(primarily for internal use) Computes the gravitationally undeflected position of an observed source position due to the specified Solar-system bodies.

REFERENCES:

1. Klioner, S. (2003), Astronomical Journal 125, 1580-1597, Section 6.

Parameters

	pos_app	[AU] Apparent position 3-vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, components in AU.
	pos_obs	[AU] Position 3-vector of observer (or the geocenter), with respect to origin at solar system barycenter, referred to ICRS axes, components in AU.
	planets	Apparent planet data containing positions and velocities for the major gravitating bodies in the solar-system.
[out]	out	[AU] Nominal position vector of observed object, with respect to origin at observer (or the geocenter), referred to ICRS axes, without gravitational deflection, components in AU. It can be the same vector as the input, but not the same as pos_obs.

Returns

0 if successful, -1 if any of the pointer arguments is NULL.

See also

grav_planets(), grav_undef()

novas_app_to_geom(), obs_planets()

Since

1.1

Author

Attila Kovacs

References grav_planets(), novas_inv_max_iter, and novas_vlen().

grav_vec()

int grav_vec	(	const double *	pos_src,
		const double *	pos_obs,
		const double *	pos_body,
		double	rmass,
		double *	out )

(primarily for internal use) Corrects position vector for the deflection of light in the gravitational field of anarbitrary body.

This function valid for an observed body within the solar system as well as for a star.

NOTES:

1. This function is called by grav_def() to calculate appropriate gravitational deflections around the massive Solar-system objects.

REFERENCES:

1. Murray, C.A. (1981) Mon. Notices Royal Ast. Society 195, 639-648.
2. See also formulae in Section B of the Astronomical Almanac, or
3. Kaplan, G. et al. (1989) Astronomical Journal 97, 1197-1210, section iii f.

Parameters

	pos_src	[AU] Position 3-vector of observed object, with respect to origin at observer (or the geocenter), components in AU.
	pos_obs	[AU] Position vector of gravitating body, with respect to origin at solar system barycenter, components in AU.
	pos_body	[AU] Position 3-vector of gravitating body, with respect to origin at solar system barycenter, components in AU.
	rmass	[1/Msun] Reciprocal mass of gravitating body in solar mass units, that is, Sun mass / body mass.
[out]	out	[AU] Position 3-vector of observed object, with respect to origin at observer (or the geocenter), corrected for gravitational deflection, components in AU. It can the same vector as the input.

Returns

0 if successful, or -1 if any of the input vectors is NULL.

See also

grav_def()

References NOVAS_AU, and novas_vlen().

local_planet()

short local_planet	(	double	jd_tt,
		const object *restrict	ss_body,
		double	ut1_to_tt,
		const on_surface *restrict	position,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec,
		double *restrict	dis )

reference_system: ICRS/GCRS
observer location: topocentric (on Earth)
position_type: apparent

Deprecated

Using the frame-based novas_sky_pos() with NOVAS_ICRS or NOVARS_GCRS as the reference system is now preferred for the equivalent calculations.

Computes the local apparent place of a solar system body, in the GCRS. This is the same as calling place() for the body for the same observer location and NOVAS_GCRS as the reference system, except the different set of return values used.

The calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992),Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	ss_body	Pointer to structure containing the body designation for the solar system body.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	position	Position of the observer
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Local apparent right ascension, referred to the GCRS (it may be NULL if not required).
[out]	dec	[deg] Local apparent right ascension, referred to the GCRS (it may be NULL if not required).
[out]	dis	[AU] Apparent distance from Earth to the body at 'jd_tt' (it may be NULL if not required).

Returns

0 if successful, or -1 if the object argument is NULL, or else 1 if the value of 'where' in structure 'location' is invalid, or 10 + the error code from place().

See also

astro_planet(), topo_planet(), virtual_planet(), app_star()

novas_sky_pos(), make_observer_at_site(), NOVAS_GCRS, get_ut1_to_tt()

References make_observer_at_site(), NOVAS_GCRS, and radec_planet().

local_star()

short local_star	(	double	jd_tt,
		double	ut1_to_tt,
		const cat_entry *restrict	star,
		const on_surface *restrict	position,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec )

reference_system: ICRS / GCRS
observer location: topocentric (on Earth)
position_type: apparent

Deprecated

Using the frame-based novas_sky_pos() with NOVAS_ICRS or NOVARS_GCRS as the reference system is now preferred for the equivalent calculations.

Computes the local apparent place of a star at date 'jd_tt', in the GCRS, given its catalog mean place, proper motion, parallax, and radial velocity.

Notwithstanding the different set of return values, this is the same as calling place_star() with the same observer location NOVAS_GCRS for an object that specifies the star.

The calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992), Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	star	Pointer to catalog entry structure containing catalog data for the object in the ICRS.
	position	Position of the observer
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Local apparent right ascension, referred to the GCRS (it may be NULL if not required).
[out]	dec	[deg] Local apparent right ascension, referred to the GCRS (it may be NULL if not required).

Returns

0 if successful, or -1 if any of the required pointer arguments is NULL, or else 20 + the error from place().

See also

place_star(), app_star(), astro_star(), topo_star(), virtual_star(), astro_planet()

novas_sky_pos(), make_observer_at_site(), NOVAS_GCRS, get_ut1_to_tt()

References make_observer_at_site(), NOVAS_GCRS, and radec_star().

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

make_cat_object(), make_redshifted_object(), make_planet(), make_ephem_object(), make_orbital_object()

novas_case_sensitive(), novas_make_frame()

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

make_observer()

short make_observer	(	enum novas_observer_place	where,
		const on_surface *	loc_surface,
		const in_space *	loc_space,
		observer *	obs )

Deprecated

It is recommended that you use one of the more specific ways of initializing the observer data structure, e.g. with make_itrf_observer(), make_gps_observer(), make_observer_at_site(), make_airborne_observer() make_solar_system_observer(), ormake_observer_at_geocenter()`. This function will be available for the foreseeable future also.

Populates an 'observer' data structure given the parameters. The output data structure may be used an the the inputs to NOVAS-C functions, such as make_frame() or place().

Parameters

	where	The location type of the observer
	loc_surface	Pointer to data structure that defines a location on Earth's surface. Used only if 'where' is NOVAS_OBSERVER_ON_EARTH, otherwise can be NULL.
	loc_space	Pointer to data structure that defines a near-Earth location in space. Used only if 'where' is NOVAS_OBSERVER_IN_EARTH_ORBIT, otherwise can be NULL.
[out]	obs	Pointer to observer data structure to populate.

Returns

0 if successful, -1 if a required argument is NULL, or 1 if the 'where' argument is invalid.

See also

make_observer_at_geocenter(), make_itrf_observer(), make_gps_observer(), make_airborne_observer(), make_observer_in_space(), make_solar_system_observer()

References observer::near_earth, NOVAS_AIRBORNE_OBSERVER, NOVAS_OBSERVER_AT_GEOCENTER, NOVAS_OBSERVER_IN_EARTH_ORBIT, NOVAS_OBSERVER_ON_EARTH, NOVAS_SOLAR_SYSTEM_OBSERVER, observer::on_surf, in_space::sc_vel, and observer::where.

make_on_surface()

int make_on_surface	(	double	latitude,
		double	longitude,
		double	height,
		double	temperature,
		double	pressure,
		on_surface *restrict	loc )

Deprecated

This old NOVAS C function has a few too many caveats. It is recommended that you use make_itrf_site() or make_gps_site() instead (both of which set default mean annual weather parameters for approximate refraction correction), and optionally set actual weather data afterwards, based on the measurements available. This function will be available for the foreseeable future also.

Populates an 'on_surface' data structure, for an observer on the surface of the Earth, with the given parameters.

Note, that because this is an original NOVAS C routine, it does not have an argument to set a humidity value (e.g. for radio refraction). As such, the humidity is set to a a default mean annual value for the location. To set an actual humidity, set the output structure's field after calling this funcion.

NOTES

1. This implementation breaks strict v1.0 ABI compatibility since it writes to (initializes) a field (humidity) that was not yet part of the on_surface structure in v1.0. As such, linking SuperNOVAS v1.1 or later with application code compiled for SuperNOVAS v1.0 can result in memory corruption or segmentation fault when this function is called. To be safe, make sure your application has been (re)compiled against SuperNOVAS v1.1 or later.
2. You can convert coordinates among ITRF realization using novas_itrf_transform(), possibly after novas_geodetic_to_cartesian() with NOVAS_GRS80_ELLIPSOID as necessary for polar ITRF coordinates.
3. You can convert Cartesian xyz locations to geodetic locations by using novas_cartesian_to_geodetic() with NOVAS_GRS80_ELLIPSOID as the reference ellipsoid parameter.
4. If you have longitude, latitude, and height defined as GPS (WGS84) values, you might want to use make_gps_site() instead, and then set weather parameters afterwards as necessary.

Parameters

	latitude	[deg] Geodetic (ITRF / GRS80) latitude; north positive.
	longitude	[deg] Geodetic (ITRF / GRS80) longitude; east positive.
	height	[m] Geodetic (ITRF / GSR80) altitude above sea level of the observer.
	temperature	[C] Temperature (degrees Celsius) [-120:70].
	pressure	[mbar] Atmospheric pressure [0:1200].
[out]	loc	Pointer to Earth location data structure to populate.

Returns

0 if successful, or -1 if the output argument is NULL (errno set to EINVAL), or if the latitude is outside of the [-90:90] range, or if the temperature or pressure values are impossible for an Earth based observer (errno set to ERANGE).

See also

make_itrf_site(), make_gps_site(), make_xyz_site()

novas_set_default_weather(), novas_cartesian_to_geodetic(), ON_SURFACE_INIT, ON_SURFACE_LOC, NOVAS_GRS80_ELLIPSOID

References make_itrf_site().

mean_star()

short mean_star	(	double	jd_tt,
		double	tra,
		double	tdec,
		enum novas_accuracy	accuracy,
		double *restrict	ira,
		double *restrict	idec )

reference system: TOD → ICRS
observer location: geocenter → SSB
position_type: apparent → geometric

Computes the barycentric ICRS position of a star, given its True of Date (TOD) apparent place, as seen by an observer at the geocenter, at date 'jd_tt'. Proper motion, parallax and radial velocity are assumed to be zero.

Equivalently, in the new frame-based approach, you might use novas_app_to_geom() with NOVAS_TOD as the reference system, and distance set to 0, and then convert the geometric position to the output ira, idec coordinates using vector2radec(). The advantage of using novas_app_to_geom() is that you are not restricted to using TOD input coordinates, but rather the apparent RA/Dec may be specified in any reference system.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992),Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
[in]	tra	[h] Geocentric apparent (TOD) right ascension, referred to true equator and equinox of date.
[in]	tdec	[deg] Geocentric apparent (TOD) declination, referred to true equator and equinox of date.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ira	[h] Barycentric geometric ICRS right ascension, or NAN if returning with an error code. It may be a pointer to the input value.
[out]	idec	[deg] Barycentric geometric ICRS declination, or NAN if returning with an error code. It may be a pointer to the input value.

Returns

0 if successful; -1 if the supplied output pointers are NULL, 1 if the iterative process did not converge after 30 iterations, or an error from vector2radec(), or else > 10 + an error from app_star().

See also

novas_app_to_geom(), NOVAS_TOD, make_observer_at_geocenter(), vector2radec()

References app_star(), CAT_ENTRY_INIT, cat_entry::dec, novas_inv_max_iter, precession(), cat_entry::ra, starvectors(), and vector2radec().

place()

short place	(	double	jd_tt,
		const object *restrict	source,
		const observer *restrict	location,
		double	ut1_to_tt,
		enum novas_reference_system	coord_sys,
		enum novas_accuracy	accuracy,
		sky_pos *restrict	output )

Computes the apparent direction of a celestial object at a specified time and in a specified coordinate system and for a given observer location.

While coord_sys defines the coordinate referfence system, it is location->where sets the origin of the reference place relative to which positions and velocities are reported.

For all but ICRS coordinate outputs, the calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

In case of a dynamical equatorial system (such as CIRS or TOD) and an Earth-based observer, the polar wobble parameters set via a prior call to cel_pole() together with he ut1_to_tt argument decide whether the resulting 'topocentric' output frame is Pseudo Earth Fixed (PEF; if cel_pole() was not set and DUT1 is 0) or ITRS (actual rotating Earth; if cel_pole() was set and ut1_to_tt includes the DUT1 component).

NOTES:

1. This version fixes a NOVAS C 3.1 issue that velocities and solar-system distances were not antedated for light-travel time.
2. In a departure from the original NOVAS C, the radial velocity for major planets (and Sun and Moon) includes gravitational redshift corrections for light originating at the surface, assuming it's observed from near Earth or else from a large distance away.
3. As of SuperNOVAS v1.3, the returned radial velocity component is a proper observer-based spectroscopic measure. In prior releases, and in NOVAS C 3.1, this was inconsistent, with pseudo LSR-based measures being returned for catalog sources.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Klioner, S. (2003), Astronomical Journal 125, 1580-1597.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	source	Pointer to a celestrial object data structure. Catalog objects musy have ICRS coordinates. You can use transform_cat() to convert other catalog systems to ICRS as necessary.
	location	The observer location, relative to which the output positions and velocities are to be calculated
	ut1_to_tt	[s] TT - UT1 time difference. Used only when 'location->where' is NOVAS_OBSERVER_ON_EARTH (1) or NOVAS_OBSERVER_IN_EARTH_ORBIT (2).
	coord_sys	The coordinate system that defines the orientation of the celestial pole. If it is NOVAS_ICRS (3), a geometric position and radial velocity is returned. For all other systems, the returned position is the apparent position including aberration and gravitational deflection corrections, and the radial velocity is in the direction the eflected light was emitted from the source.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	output	Data structure to populate with the result.

Returns

0 if successful,
1 if 'coord_sys' is invalid,
2 if 'accuracy' is invalid,
3 if the observer is at or very near (within ~1.5m of) the observed location,
10–40: error is 10 + the error ephemeris(),
40–50: error is 40 + the error from geo_posvel(),
50–70: error is 50 + error from light_time2(),
70–80: error is 70 + error from grav_def(),
80–90: error is 80 + error from cio_location(),
90–100: error is 90 + error from cio_basis().

See also

place_star(), place_icrs(), place_gcrs(), place_cirs(), radec_star(), radec_planet()

novas_sky_pos(), novas_geom_posvel(), get_ut1_to_tt()

References aberration(), bary2obs(), d_light(), ephemeris(), era(), gcrs_to_cirs(), gcrs_to_j2000(), gcrs_to_mod(), gcrs_to_tod(), grav_bodies_full_accuracy, grav_bodies_reduced_accuracy, grav_planets(), light_time2(), make_observer_at_geocenter(), NOVAS_BARYCENTER, NOVAS_CATALOG_OBJECT, NOVAS_CIRS, NOVAS_EARTH_INIT, NOVAS_FULL_ACCURACY, NOVAS_ICRS, NOVAS_ITRS, NOVAS_J2000, NOVAS_MOD, NOVAS_REDUCED_ACCURACY, NOVAS_SUN_INIT, NOVAS_TIRS, NOVAS_TOD, novas_vlen(), obs_planets(), obs_posvel(), proper_motion(), rad_vel2(), spin(), starvectors(), tt2tdb(), and vector2radec().

place_icrs()

int place_icrs	(	double	jd_tt,
		const object *restrict	source,
		enum novas_accuracy	accuracy,
		sky_pos *restrict	pos )

reference_system: ICRS / GCRS
observer location: geocenter
position_type: geometric

Computes the International Celestial Reference System (ICRS) position of a source. (from the geocenter). Unlike place_gcrs(), this version does not include aberration or gravitational deflection corrections.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date of observation.
	source	Catalog source or solar_system body.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	pos	Structure to populate with the calculated geometric ICRS position data for a fictitous geocentric observer. (Unlike place_gcrs(), the calculated coordinates do not account for aberration or gravitational deflection).

Returns

0 if successful, or -1 if any of the input pointer arguments is NULL, or else an error from place().

Since

1.0

Author

Attila Kovacs

See also

place_gcrs(), place_cirs(), place_tod(), mean_star()

novas_geom_posvel(), NOVAS_GCRS, make_observer_at_geocenter()

References NOVAS_ICRS, and place().

place_star()

int place_star	(	double	jd_tt,
		const cat_entry *restrict	star,
		const observer *restrict	obs,
		double	ut1_to_tt,
		enum novas_reference_system	system,
		enum novas_accuracy	accuracy,
		sky_pos *restrict	pos )

Computes the apparent place of a star at the specified date, given its catalog mean place, proper motion, parallax, and radial velocity.

See place() for more information.

It is effectively the same as calling place(), except for the cat_entry type target argument.

For all but ICRS coordinate outputs, the calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992),Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	star	Pointer to catalog entry structure containing catalog data for the object in the ICRS.
	obs	Observer location (NULL defaults to geocentric)
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	system	The type of coordinate reference system in which coordinates are to be returned.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	pos	The position and radial velocity of of the catalog source in the specified coordinate system and relative to the specified observer location (if applicable)

Returns

0 if successful, or -1 if one of the required arguments is NULL, or else 1 if the observer location is invalid, or an error code from place().

Author

Attila Kovacs

Since

1.0

See also

novas_sky_pos(), novas_geom_posvel(), get_ut1_to_tt()

References NOVAS_CATALOG_OBJECT, place(), object::star, and object::type.

planet_lon()

double planet_lon	(	double	t,
		enum novas_planet	planet )

Returns the planetary longitude, for Mercury through Neptune, w.r.t.

mean dynamical ecliptic and equinox of J2000, with high order terms omitted (Simon et al. 1994, 5.8.1-5.8.8).

REFERENCES:

1. IERS Conventions Chapter 5, Eq. 5.44.

Parameters

t	[cy] Julian centuries since J2000
planet	Novas planet id, e.g. NOVAS_MARS.

Returns

[rad] The approximate longitude of the planet in radians [-π:π], or NAN if the planet id is out of range.

See also

accum_prec(), nutation_angles(), NOVAS_JD_J2000

Since

1.0

Author

Attila Kovacs

References NOVAS_NEPTUNE, and TWOPI.

radec_planet()

int radec_planet	(	double	jd_tt,
		const object *restrict	ss_body,
		const observer *restrict	obs,
		double	ut1_to_tt,
		enum novas_reference_system	sys,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec,
		double *restrict	dis,
		double *restrict	rv )

Computes the place of a solar system body at the specified time for an observer in the specified coordinate system.

This is the same as calling place() with the same arguments, except the different set of return values used.

Notwithstanding the different set of return values, this is the same as calling place_planet() with the same arguments.

For all but ICRS coordinate outputs, the calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992),Chapter 3.

Parameters

	jd_tt	[day] Terretrial Time (TT) based Julian date.
	ss_body	Pointer to structure containing the body designation for the solar system body.
	obs	Observer location. It may be NULL if not relevant.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	sys	Coordinate reference system in which to produce output values
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Topocentric apparent right ascension in hours, referred to the true equator and equinox of date, or NAN when returning with an error code. (It may be NULL if not required)
[out]	dec	[deg] Topocentric apparent declination in degrees referred to the true equator and equinox of date, or NAN when returning with an error code. (It may be NULL if not required)
[out]	dis	[AU] True distance from Earth to the body at 'jd_tt' in AU, or NAN when returning with an error code. (It may be NULL if not needed).
[out]	rv	[AU/day] radial velocity relative ot observer, or NAN when returning with an error code. (It may be NULL if not required)

Returns

0 if successful, or -1 if the object argument is NULL or if the value of 'where' in structure 'location' is invalid, or 10 + the error code from place().

Since

1.0

Author

Attila Kovacs

See also

radec_star()

novas_sky_pos(), novas_geom_posvel()

References sky_pos::dec, sky_pos::dis, NOVAS_EPHEM_OBJECT, NOVAS_ORBITAL_OBJECT, NOVAS_PLANET, place(), sky_pos::ra, sky_pos::rv, and SKY_POS_INIT.

radec_star()

int radec_star	(	double	jd_tt,
		const cat_entry *restrict	star,
		const observer *restrict	obs,
		double	ut1_to_tt,
		enum novas_reference_system	sys,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec,
		double *restrict	rv )

Computes the place of a star at date 'jd_tt', for an observer in the specified coordinate system, given the star's ICRS catalog place, proper motion, parallax, and radial velocity.

Notwithstanding the different set of return values, this is the same as calling place_star() with the same arguments.

For all but ICRS coordinate outputs, the calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992), Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	star	Pointer to catalog entry structure containing catalog data for the object in the ICRS.
	obs	Observer location. It may be NULL if not relevant.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	sys	Coordinate reference system in which to produce output values
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Topocentric right ascension in hours, referred to true equator and equinox of date 'jd_tt' or NAN when returning with an error code. (It may be NULL if not required)
[out]	dec	[deg] Topocentric declination in degrees, referred to true equator and equinox of date 'jd_tt' or NAN when returning with an error code. (It may be NULL if not required)
[out]	rv	[AU/day] radial velocity relative ot observer, or NAN when returning with an error code. (It may be NULL if not required)

Returns

0 if successful, -1 if a required pointer argument is NULL, or else 20 + the error from place_star().

Since

1.0

Author

Attila Kovacs

See also

radec_planet()

novas_sky_pos(), novas_geom_posvel()

References sky_pos::dec, place_star(), sky_pos::ra, sky_pos::rv, and SKY_POS_INIT.

readeph()

double * readeph	(	int	mp,
		const char *restrict	name,
		double	jd_tdb,
		int *restrict	error )

Deprecated

This old ephemeris reader is prone to memory leaks, and lacks some useful functionality. Users are strongly encouraged to use the new novas_ephem_provider / novas_set_ephem_provider() instead, for dynamically configured implementations at runtime. This prototype is provided only to extend support for legacy NOVAS applications only, where an inplementation had to be linked always.

Legacy NOVAS C function to handle position and velocity calculations for Solar-system sources, beyond the major planets. This function can be defined by an external module, as per the NOVAS C way, provided you compile SuperNOVAS with the READPH_SOURCE option set to specify the source(s) that implement it (in config.mk or the environment). If READEPH_SOURCE in not defined during the build of SuperNOVAS, then this function will not be used by SuperNOVAS, nor will be implemented by it.

Parameters

	mp	The ID number of the solar-system body for which the position are desired. An actual implementation might use this and/or the name to identify the object.
	name	The name of the solar-system body (usually upper-case). An actual implementation might use this and/or mp to identify the object.
	jd_tdb	[day] Barycentric Dynamical Time (TDB) based Julian date for which to find the position and velocity.
[out]	error	Pointer to integer to populate with the error status: 0 if successful, -1 if any of the pointer arguments are NULL, or some non-zero value if the was an error s.t. the position and velocity vector should not be used.

Returns

[AU, AU/day] A newly allocated 6-vector in rectangular equatorial coordinates, containing the heliocentric position coordinates in AU, followed by hte heliocentric velocity components in AU/day. The caller is responsible for calling free() on the returned value when it is no longer needed.

See also

novas_ephem_provider

References novas_inv_max_iter, and rad_vel().

set_cio_locator_file()

int set_cio_locator_file

(

const char *restrict

filename

)

Deprecated

SuperNOVAS no longer uses a NOVAS-type CIO locator file, or accesses one in any way. This function is now a dummy.

It used to set the CIO interpolaton data file to use to interpolate CIO locations vs the GCRS. As of version 1.5, this call does exactly nothing. It simply returns 0.

Parameters

filename

(unused) Used to be the path (preferably absolute path) CIO_RA.TXT or else to the binary cio_ra.bin data, or NULL to disable using a CIO locator file altogether.

Returns

0

See also

cio_location()

Since

1.0

Author

Attila Kovacs

sidereal_time()

short sidereal_time	(	double	jd_ut1_high,
		double	jd_ut1_low,
		double	ut1_to_tt,
		enum novas_equinox_type	gst_type,
		enum novas_earth_rotation_measure	erot,
		enum novas_accuracy	accuracy,
		double *restrict	gst )

Deprecated

Use novas_gmst() or novas_gast() instead to get the same results simpler.

Computes the Greenwich sidereal time, either mean or apparent, at the specified Julian date. The Julian date can be broken into two parts if convenient, but for the highest precision, set 'jd_high' to be the integral part of the Julian date, and set 'jd_low' to be the fractional part.

NOTES:

1. Contains fix for known sidereal time units bug.
2. As of version 1.5.0, the function uses Eq 42 of Capitaine et al. (2003) exclusively. In prior versions, including NOVAS C the same method was provided twice, with the only difference being an unnecessary change of coordinate basis to GCRS. This latter, mor roundabout way of getting the same answer has been eliminated.<.li>

REFERENCES:

1. Capitaine, N. et al. (2003), Astronomy and Astrophysics 412, 567-586, eq. (42).
2. Kaplan, G. (2005), US Naval Observatory Circular 179.

Parameters

	jd_ut1_high	[day] High-order part of UT1 Julian date.
	jd_ut1_low	[day] Low-order part of UT1 Julian date. (You can leave it at zero if 'jd_high' specified the date with sufficient precision)
	ut1_to_tt	[s] TT - UT1 Time difference in seconds
	gst_type	NOVAS_MEAN_EQUINOX (0) or NOVAS_TRUE_EQUINOX (1), depending on whether wanting mean or apparent GST, respectively.
	erot	Unused as of 1.5.0.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	gst	[h] Greenwich (mean or apparent) sidereal time, in hours [0:24]. (In case the returned error code is >1 the gst value will be set to NAN.)

Returns

0 if successful, or -1 if the 'gst' argument is NULL, 1 if 'accuracy' is

See also

novas_gmst(), novas_gast(), novas_time_gst()

era(), get_ut1_to_tt()

References NOVAS_FULL_ACCURACY, novas_gast(), novas_gmst(), NOVAS_REDUCED_ACCURACY, and NOVAS_TRUE_EQUINOX.

ter2cel()

short ter2cel	(	double	jd_ut1_high,
		double	jd_ut1_low,
		double	ut1_to_tt,
		enum novas_earth_rotation_measure	erot,
		enum novas_accuracy	accuracy,
		enum novas_equatorial_class	coordType,
		double	xp,
		double	yp,
		const double *	in,
		double *	out )

Deprecated

This function can be confusing to use due to the output coordinate system being specified by a combination of two options. Use itrs_to_cirs() or itrs_to_tod() instead. You can then follow these with other conversions to GCRS (or whatever else) as appropriate.

Rotates a vector from the terrestrial to the celestial system. Specifically, it transforms a vector in the ITRS (rotating earth-fixed system) to the True of Date (TOD), CIRS, or GCRS (a local space-fixed system) by applying rotations for polar motion, Earth rotation (for TOD); and nutation, precession, and the dynamical-to-GCRS frame tie (for GCRS).

If 'system' is NOVAS_CIRS then method EROT_ERA must be used. Similarly, if 'system' is NOVAS_TOD then method must be EROT_ERA. Otherwise an error 3 is returned.

If both 'xp' and 'yp' are set to 0 no polar motion is included in the transformation.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Kaplan, G. H. (2003), 'Another Look at Non-Rotating Origins', Proceedings of IAU XXV Joint Discussion 16.

Parameters

	jd_ut1_high	[day] High-order part of UT1 Julian date.
	jd_ut1_low	[day] Low-order part of UT1 Julian date.
	ut1_to_tt	[s] TT - UT1 Time difference in seconds
	erot	Unused.
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
	coordType	Output coordinate class NOVAS_REFERENCE_CLASS (0, or any value other than 1) or NOVAS_DYNAMICAL_CLASS (1). Use the former if the output coordinates are to be in the GCRS, and the latter if they are to be in CIRS or TOD (the 'erot' parameter selects which dynamical system to use for the output.)
	xp	[arcsec] Conventionally-defined X coordinate of celestial intermediate pole with respect to ITRS pole. If you have defined pole offsets the old (pre IAU2000) way, via cel_pole(), then use 0 here.
	yp	[arcsec] Conventionally-defined Y coordinate of celestial intermediate pole with respect to ITRS pole. If you have defined pole offsets the old (pre IAU2000) way, via cel_pole(), then use 0 here.
	in	Position vector, geocentric equatorial rectangular coordinates, referred to ITRS axes (terrestrial system) in the normal case where 'option' is NOVAS_GCRS (0).
[out]	out	Position vector, equatorial rectangular coordinates in the specified output system (GCRS if 'class' is NOVAS_REFERENCE_CLASS; or else either CIRS if 'erot' is EROT_ERA, or TOD if 'erot' is EROT_GST). It may be the same vector as the input.

Returns

0 if successful, -1 if either of the vector arguments is NULL, 1 if 'accuracy' is invalid, 2 if 'method' is invalid 10–20, or else 10 + the error from cio_location(), or 20 + error from cio_basis().

See also

novas_hor_to_app(), itrs_to_cirs(), cirs_to_gcrs(), itrs_to_tod(), tod_to_j2000(), frame_tie(), cel2ter()

References cirs_to_gcrs(), era(), EROT_ERA, EROT_GST, NOVAS_DYNAMICAL_CLASS, NOVAS_FULL_ACCURACY, novas_gast(), NOVAS_REDUCED_ACCURACY, spin(), tod_to_gcrs(), wobble(), WOBBLE_ITRS_TO_PEF, and WOBBLE_ITRS_TO_TIRS.

topo_planet()

short topo_planet	(	double	jd_tt,
		const object *restrict	ss_body,
		double	ut1_to_tt,
		const on_surface *restrict	position,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec,
		double *restrict	dis )

reference_system: TOD
observer location: topocentric (on Earth)
position_type: apparent

Deprecated

Using the frame-based novas_sky_pos() with NOVAS_TOD as the reference system is now preferred for topocentric calculations.

Computes the topocentric apparent place of a solar system body at the specified time. This is the same as calling place() for the body for the same observer location and NOVAS_TOD as the reference system, except the different set of return values used.

The calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992),Chapter 3.

Parameters

	jd_tt	[day] Terretrial Time (TT) based Julian date.
	ss_body	Pointer to structure containing the body designation for the solar system body.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	position	Position of the observer
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Topocentric apparent right ascension, referred to the true equator and equinox of date. (It may be NULL if not required)
[out]	dec	[deg] Topocentric apparent declination, referred to the true equator and equinox of date. (It may be NULL if not required)
[out]	dis	[AU] Apparent distance from Earth to the body at 'jd_tt' (may be NULL if not needed).

Returns

0 if successful, or -1 if the object argument is NULL, or else 1 if the value of 'where' in structure 'location' is invalid, or 10 + the error from place().

See also

app_planet(), local_planet(), topo_planet(), virtual_planet(), astro_star()

novas_sky_pos(), make_observer_at_site(), NOVAS_TOD, get_ut1_to_tt()

References make_observer_at_site(), NOVAS_TOD, and radec_planet().

topo_star()

short topo_star	(	double	jd_tt,
		double	ut1_to_tt,
		const cat_entry *restrict	star,
		const on_surface *restrict	position,
		enum novas_accuracy	accuracy,
		double *restrict	ra,
		double *restrict	dec )

reference_system: TOD
observer location: topocentric (on Earth)
position_type: apparent

Deprecated

Using the frame-based novas_sky_pos() with NOVAS_TOD as the reference system is now preferred for topocentric calculations.

Computes the topocentric (True of Date; TOD) apparent place of a star at date 'jd_tt', given its ICRS catalog place, proper motion, parallax, and radial velocity.

Notwithstanding the different set of return values, this is the same as calling place_star() with the same observer location and NOVAS_TOD for an object that specifies the star.

The calculated positions and velocities include aberration corrections for the moving frame of the observer as well as gravitational deflection due to the Sun and Earth and other major gravitating bodies in the Solar system, provided planet positions are available via a novas_planet_provider function.

REFERENCES:

1. Kaplan, G. H. et. al. (1989). Astron. Journ. 97, 1197-1210.
2. Explanatory Supplement to the Astronomical Almanac (1992), Chapter 3.

Parameters

	jd_tt	[day] Terrestrial Time (TT) based Julian date.
	ut1_to_tt	[s] Difference TT-UT1 at 'jd_tt', in seconds of time.
	star	Pointer to catalog entry structure containing catalog data for the object in the ICRS.
	position	Position of the observer
	accuracy	NOVAS_FULL_ACCURACY (0) or NOVAS_REDUCED_ACCURACY (1)
[out]	ra	[h] Topocentric appatent right ascension, referred to true equator and equinox of date 'jd_tt'. (It may be NULL if not required)
[out]	dec	[deg] Topocentric apparent declination, referred to true equator and equinox of date 'jd_tt'. (It may be NULL if not required)

Returns

0 if successful, -1 if a required pointer argument is NULL, or else 20 + the error from place_star().

See also

place_star(), app_star(), local_star(), topo_star(), virtual_star(), astro_planet()

novas_sky_pos(), make_observer_at_site(), NOVAS_TOD, get_ut1_to_tt()

References make_observer_at_site(), NOVAS_TOD, and radec_star().