Precise astronomical time specification, supporting all relevant astronomical timescales (UT1, UTC, TAI, GPS, TT, TDB, TCG, and TCB). More...

#include <supernovas.h>

Inheritance diagram for supernovas::Time:

Public Member Functions
	Time (const novas_timespec *t)
	Instantiates an astrometric time instance with the specified SuperNOVAS C astrometric time specification data structure.
	Time (const std::string &timestamp, const EOP &eop, enum novas_timescale timescale=NOVAS_UTC)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (const std::string &timestamp, int leap_seconds, double dUT1, enum novas_timescale timescale=NOVAS_UTC)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (const struct timespec *t, const EOP &eop)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (const struct timespec *t, int leap_seconds, double dUT1)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (double jd, const EOP &eop, enum novas_timescale timescale=NOVAS_TT)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (double jd, int leap_seconds, double dUT1, enum novas_timescale timescale=NOVAS_TT)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (long ijd, double fjd, const EOP &eop, enum novas_timescale timescale=NOVAS_TT)
	Instantiates an astrometric time instance with the specified time parameters.
	Time (long ijd, double fjd, int leap_seconds, double dUT1, enum novas_timescale timescale=NOVAS_TT)
	Instantiates an astrometric time instance with the specified time parameters.
const novas_timespec *	_novas_timespec () const
	Returns the underlying C astrometric time specification data structure.
int	day_of_week (enum novas_timescale timescale=NOVAS_UTC) const
	Returns the day of week index (1..7) for this time instance.
Interval	dUT1 () const
	Returns the UT1 - UTC time difference for this time instance, as was provided during instantiation.
double	epoch () const
	Returns the Julian coordinate epoch year of this time instance.
bool	equals (const Time &time, const Interval &precision) const
	Checks if this time instance is the same as another time within the specified precision.
bool	equals (const Time &time, double seconds=Unit::us) const
	Checks if this time instance is the same as another time within the specified precision.
TimeAngle	era () const
	Returns the Earth Rotation Angle (ERA), which measures the angle between the Terrestrial Intermediate Origin (TIO) and the Celestial Intermediate Origin (CIO) in the IAU 2000 convention.
TimeAngle	gmst () const
	Returns the Greenwich Mean Sidereal Time (GMST) for this time instance.
TimeAngle	gst (enum novas_accuracy accuracy=NOVAS_FULL_ACCURACY) const
	Returns the Greenwich (Apparent) Sidereal Time (GST / GaST) for this time instance.
double	jd (enum novas_timescale timescale=NOVAS_TT) const
	Returns the precise Julian Date of this time instance, in the specific timescale of choice.
long	jd_day (enum novas_timescale timescale=NOVAS_TT) const
	Returns the integer Julian day of this time instance, in the specific timescale of choice.
double	jd_frac (enum novas_timescale timescale=NOVAS_TT) const
	Returns the factional Julian Day (MJD) of this time instance, in the specific timescale of choice.
int	leap_seconds () const
	Returns the leap seconds for this time instance, as was provided during instantiation.
TimeAngle	lst (const Site &site, enum novas_accuracy accuracy=NOVAS_FULL_ACCURACY) const
	Returns the Local (Apparent) Sidereal Time for this time instance.
double	mjd (enum novas_timescale timescale=NOVAS_TT) const
	Returns the precise Modified Julian Date (MJD) this time instance, in the specific timescale of choice.
long	mjd_day (enum novas_timescale timescale=NOVAS_TT) const
	Returns the integer Modified Julian Day (MJD) of this time instance, in the specific timescale of choice.
double	mjd_frac (enum novas_timescale timescale=NOVAS_TT) const
	Returns the integer Modified Julian Day (MJD) of this time instance, in the specific timescale of choice.
Angle	moon_phase () const
	Returns the phase of the Moon at this time instance.
Time	next_moon_phase (const Angle &phase) const
	Returns the next time, after this time instance, when the Moon will be in the specified phase.
Interval	offset_from (const Time &time, enum novas_timescale timescale=NOVAS_TT) const
	Returns the difference of this time from the specified other time, in the specified timescale.
bool	operator!= (const Time &time) const
	Checks if this time instance differs from another time by more than 1 μs.
Time	operator+ (const Interval &delta) const
	Returns an offset time in the backward direction.
Time	operator+ (double seconds) const
	Returns an offset time.
Interval	operator- (const CalendarDate &other) const
Time	operator- (const Interval &delta) const
	Returns an offset time.
Interval	operator- (const Time &other) const
	Returns the difference of this time from the specified other time, in regular Earth-based time measures (GPS, TAI, TT – and also UTC assuming no change in leap seconds).
Time	operator- (double seconds) const
	Returns an offset time in the backwards direction.
bool	operator< (const Time &other) const
	Checks if this time is prior to the specified other time, at the full precision of the representation.
bool	operator<= (const Time &other) const
	Checks if this time is the same as or before the specified other time, at 1 μs resolution.
bool	operator== (const Time &time) const
	Checks if this time instance is the same as another time within 1 μs.
bool	operator> (const Time &other) const
	Checks if this time is after to the specified other time, at the full precision of the representation.
bool	operator>= (const Time &other) const
	Checks if this time is the same as or after the specified other time, at 1 μs resolution.
Time	shifted (const Interval &offset, enum novas_timescale timescale=NOVAS_TT) const
	Returns an offset time.
Time	shifted (double seconds, enum novas_timescale timescale=NOVAS_TT) const
	Returns an offset time.
TimeAngle	time_of_day (enum novas_timescale timescale=NOVAS_TT) const
	Returns the time of (calendar) day of this time instance in the timescale of choice.
CalendarDate	to_calendar_date (const Calendar &calendar=Calendar::astronomical(), enum novas_timescale timescale=NOVAS_UTC) const
	Returns a calendar date, in the calendar of choice, and in the timescale of choice, for time instance.
CalendarDate	to_calendar_date (enum novas_timescale timescale) const
	Returns the astronomical calendar date instance for this astrometric time.
std::string	to_epoch_string (int decimals=2) const
	Returns the string representation of the Julian coordinate epoch corresponding to this timestamp.
std::string	to_iso_string () const
	Returns an ISO 8601 timestamp for this time instance.
std::string	to_string (enum novas_timescale timescale=NOVAS_UTC) const
	Returns a string representation (a timestamp) of this time instance.
time_t	unix_time (long *nanos=NULL) const
	Returns the precise UNIX time (UTC) corresponding to this time instance.
Public Member Functions inherited from supernovas::Validating
bool	is_valid () const
	Returns the previously set 'valid' stae of the implementing instance.
	operator bool () const
	Objects that implement Validating can be used in conditionals directly, without explicitly calling is_valid().

Static Public Member Functions
static const Time &	b1900 ()
	Returns the astrometric time for the B1900 epoch.
static const Time &	b1950 ()
	Returns the astrometric time for the B1950 epoch.
static Time	from_mjd (double mjd, const EOP &eop, enum novas_timescale timescale=NOVAS_TT)
	Returns a new astrometric time instance for a given Modified Julian Date (MJD), specified in the timescale of choice.
static Time	from_mjd (double mjd, int leap_seconds, double dUT1, enum novas_timescale timescale=NOVAS_TT)
	Returns a new astrometric time instance for a given Modified Julian Date (MJD), specified in the timescale of choice.
static const Time &	hip ()
	Returns the astrometric time for the Hipparcos catalog epoch (which is J1991.25).
static const Time &	j2000 ()
	Returns the astrometric time for the J2000 epoch.
static Time	now (const EOP &eop)
	Resturns a new astrometric time instance for the current time.
static const Time &	undefined ()
	Returns a reference to a statically defined standard invalid astrometric time.

Additional Inherited Members
Protected Member Functions inherited from supernovas::Validating
	Validating ()
	dummy constructor;
Protected Attributes inherited from supernovas::Validating
bool	_valid = false
	the state variable.

Detailed Description

Precise astronomical time specification, supporting all relevant astronomical timescales (UT1, UTC, TAI, GPS, TT, TDB, TCG, and TCB).

See also: Interval, TimeAngle, Observer

Constructor & Destructor Documentation

◆ Time() [1/9]

supernovas::Time::Time	(	double	jd,
		int	leap_seconds,
		double	dUT1,
		enum novas_timescale	timescale = NOVAS_TT )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

jd	[day] Julian date (in the selected timescale)
leap_seconds	[s] leap seconds, that is TAI - UTC (default: 0)
dUT1	[s] UT1 - UTC time difference, e.g. from the IERS Bulletins or service (default: 0.0).
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References supernovas::Validating::_valid, dUT1(), jd(), leap_seconds(), and novas_set_time().

◆ Time() [2/9]

supernovas::Time::Time	(	double	jd,
		const EOP &	eop,
		enum novas_timescale	timescale = NOVAS_TT )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

jd	[day] Julian date (in the selected timescale)
eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References dUT1(), jd(), and leap_seconds().

◆ Time() [3/9]

supernovas::Time::Time	(	long	ijd,
		double	fjd,
		int	leap_seconds,
		double	dUT1,
		enum novas_timescale	timescale = NOVAS_TT )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

ijd	[day] integer part of Julian date (in the selected timescale)
fjd	[day] fractional part of Julian date (in the selected timescale)
leap_seconds	[s] leap seconds, that is TAI - UTC (default: 0)
dUT1	[s] UT1 - UTC time difference, e.g. from the IERS Bulletins or service (default: 0.0).
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References supernovas::Validating::_valid, dUT1(), leap_seconds(), and novas_set_split_time().

◆ Time() [4/9]

supernovas::Time::Time	(	long	ijd,
		double	fjd,
		const EOP &	eop,
		enum novas_timescale	timescale = NOVAS_TT )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

ijd	[day] integer part of Julian date (in the selected timescale)
fjd	[day] fractional part of Julian date (in the selected timescale)
eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References dUT1(), and leap_seconds().

◆ Time() [5/9]

supernovas::Time::Time	(	const std::string &	timestamp,
		int	leap_seconds,
		double	dUT1,
		enum novas_timescale	timescale = NOVAS_UTC )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

timestamp	A precision timestamp, such as an ISO 8601 timestamp.
leap_seconds	[s] leap seconds, that is TAI - UTC (default: 0)
dUT1	[s] UT1 - UTC time difference, e.g. from the IERS Bulletins or service (default: 0.0).
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip(); novas_parse_date(), novas_parse_ido_date(), novas_parse_date_format(), novas_parse_timescale() for more managed parsing from strings.

References supernovas::Validating::_valid, dUT1(), leap_seconds(), and novas_set_str_time().

◆ Time() [6/9]

supernovas::Time::Time	(	const std::string &	timestamp,
		const EOP &	eop,
		enum novas_timescale	timescale = NOVAS_UTC )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

timestamp	A precision timestamp, such as an ISO 8601 timestamp.
eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.
timescale	(optional) Astronomical timescale (default: TT).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip(); novas_parse_date(), novas_parse_ido_date(), novas_parse_date_format(), novas_parse_timescale() for more managed parsing from strings.

References dUT1(), and leap_seconds().

◆ Time() [7/9]

supernovas::Time::Time	(	const struct timespec *	t,
		int	leap_seconds,
		double	dUT1 )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

t	A precision POSIX standard UTC timestamp.
leap_seconds	[s] leap seconds, that is TAI - UTC (default: 0)
dUT1	[s] UT1 - UTC time difference, e.g. from the IERS Bulletins or service (default: 0.0).

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References supernovas::Validating::_valid, dUT1(), leap_seconds(), novas_set_unix_time(), and NOVAS_UTC.

◆ Time() [8/9]

supernovas::Time::Time	(	const struct timespec *	t,
		const EOP &	eop )

Instantiates an astrometric time instance with the specified time parameters.

Parameters

t	A precision POSIX standard UTC timestamp.
eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References dUT1(), and leap_seconds().

◆ Time() [9/9]

supernovas::Time::Time ( const novas_timespec * t )

explicit

Instantiates an astrometric time instance with the specified SuperNOVAS C astrometric time specification data structure.

Parameters

t	pointer to the SuperNOVAS C astrometric time specification data structure.

See also: now(), from_mjd(), j2000(), b1950(), b1900(), hip()

References supernovas::Validating::_valid, novas_timespec::fjd_tt, novas_timespec::tt2tdb, and novas_timespec::ut1_to_tt.

Member Function Documentation

◆ _novas_timespec()

const novas_timespec * supernovas::Time::_novas_timespec ( ) const

Returns the underlying C astrometric time specification data structure.

Returns: a pointer to the underlying C time specification data structure.

◆ b1900()

const Time & supernovas::Time::b1900 ( )

static

Returns the astrometric time for the B1900 epoch.

Returns: the astrometric time for B1900.

See also: b1950(), j2000(), hip()

References NOVAS_JD_B1900, and NOVAS_TT.

◆ b1950()

const Time & supernovas::Time::b1950 ( )

static

Returns the astrometric time for the B1950 epoch.

Returns: the astrometric time for B1950.

See also: b1900(), j2000(), hip()

References NOVAS_JD_B1950, and NOVAS_TT.

◆ day_of_week()

int supernovas::Time::day_of_week ( enum novas_timescale timescale = NOVAS_UTC ) const

Returns the day of week index (1..7) for this time instance.

Parameters

timescale (optional) the timescale in which to return the result (default: UTC).

Returns: The day-of-week index [1:7] in the same timescale as the input date. 1:Monday ... 7:Sunday, or else 0 if the input Julian Date is NAN.

References jd(), and novas_day_of_week().

◆ dUT1()

Interval supernovas::Time::dUT1 ( ) const

Returns the UT1 - UTC time difference for this time instance, as was provided during instantiation.

Returns: [s] The UT1 - UTC time difference.

See also: leap_seconds()

References supernovas::Validating::is_valid().

Referenced by Time(), Time(), Time(), Time(), Time(), Time(), Time(), Time(), from_mjd(), next_moon_phase(), operator-(), and shifted().

◆ epoch()

double supernovas::Time::epoch ( ) const

Returns the Julian coordinate epoch year of this time instance.

Returns: [yr] the Julian coordinate epoch (e.g. 2000.0 for J2000).

References jd(), NOVAS_JD_J2000, and NOVAS_JULIAN_YEAR_DAYS.

Referenced by to_epoch_string().

◆ equals() [1/2]

bool supernovas::Time::equals	(	const Time &	time,
		const Interval &	precision ) const

Checks if this time instance is the same as another time within the specified precision.

Parameters

Time of observation and astronomical timescales	the other time
precision	(optional) The precision for the comparison (default: 1 μs).

Returns: true if the two times are equal within the specified precision, otherwise false.

See also: operator==(), operator!=()

References equals(), and supernovas::Interval::seconds().

◆ equals() [2/2]

bool supernovas::Time::equals	(	const Time &	time,
		double	precision = Unit::us ) const

Checks if this time instance is the same as another time within the specified precision.

Parameters

Time of observation and astronomical timescales	the other time
precision	[s] (optional) The precision for the comparison (default: 1 &mus)

Returns: true if the two times are equal within the specified precision, otherwise false.

See also: operator==(), operator!=()

References novas_diff_time().

Referenced by equals(), operator!=(), and operator==().

◆ era()

TimeAngle supernovas::Time::era ( ) const

Returns the Earth Rotation Angle (ERA), which measures the angle between the Terrestrial Intermediate Origin (TIO) and the Celestial Intermediate Origin (CIO) in the IAU 2000 convention.

Returns: The Earth Rotation Angle (ERA) as a time-angle.

References supernovas::Unit::deg, and supernovas::Validating::is_valid().

◆ from_mjd() [1/2]

Time supernovas::Time::from_mjd	(	double	mjd,
		const EOP &	eop,
		enum novas_timescale	timescale = NOVAS_TT )

static

Returns a new astrometric time instance for a given Modified Julian Date (MJD), specified in the timescale of choice.

Parameters

mjd	[day] Modified Julian Date, in the timescale of choice
eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.
timescale	(optional) timescale in which MJD was specified (default: TT)

Returns: a new astrometric time instance for the given MJD date.

See also: Time(), now(), j2000(), b1950(), b1900(), hip()

References supernovas::EOP::dUT1(), from_mjd(), supernovas::EOP::leap_seconds(), mjd(), and supernovas::Interval::seconds().

◆ from_mjd() [2/2]

Time supernovas::Time::from_mjd	(	double	mjd,
		int	leap_seconds,
		double	dUT1,
		enum novas_timescale	timescale = NOVAS_TT )

static

Returns a new astrometric time instance for a given Modified Julian Date (MJD), specified in the timescale of choice.

Parameters

mjd	[day] Modified Julian Date, in the timescale of choice
leap_seconds	[s] leap seconds, that is TAI - UTC (default: 0)
dUT1	[s] UT1 - UTC time difference, e.g. from the IERS Bulletins or service (default: 0.0).
timescale	(optional) timescale in which MJD was specified (default: TT)

Returns: a new astrometric time instance for the given MJD date.

See also: Time(), now(), j2000(), b1950(), b1900(), hip()

References dUT1(), supernovas::Validating::is_valid(), leap_seconds(), mjd(), and NOVAS_JD_MJD0.

Referenced by from_mjd().

◆ gmst()

TimeAngle supernovas::Time::gmst ( ) const

Returns the Greenwich Mean Sidereal Time (GMST) for this time instance.

Returns: the GMST time-angle

See also: gst(), lst()

References supernovas::Unit::hour_angle, supernovas::Validating::is_valid(), novas_get_time(), novas_gmst(), and NOVAS_UT1.

◆ gst()

TimeAngle supernovas::Time::gst ( enum novas_accuracy accuracy = NOVAS_FULL_ACCURACY ) const

Returns the Greenwich (Apparent) Sidereal Time (GST / GaST) for this time instance.

Parameters

accuracy NOVAS_FULL_ACCURACY (0) for μs-level precision or NOVAS_REDUCED_ACCURACY (1) for &ms-level precison.

Returns: the GST / GaST time-angle.

See also: gmst(), lst(), era()

References supernovas::Unit::hour_angle, supernovas::Validating::is_valid(), and novas_time_gst().

◆ hip()

const Time & supernovas::Time::hip ( )

static

Returns the astrometric time for the Hipparcos catalog epoch (which is J1991.25).

Returns: the astrometric time for the Hipparcos catalog epoch, that is J1991.25.

See also: j2000(), b1950, b1900()

References NOVAS_JD_HIP, and NOVAS_TT.

◆ j2000()

const Time & supernovas::Time::j2000 ( )

static

Returns the astrometric time for the J2000 epoch.

Returns: the astrometric time for J2000, that is 12:00:00 TT, 1 Jan 2000.

See also: b1950, b1900(), hip()

References NOVAS_JD_J2000, and NOVAS_TT.

Referenced by supernovas::Ecliptic::to_mod().

◆ jd()

double supernovas::Time::jd ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the precise Julian Date of this time instance, in the specific timescale of choice.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the precise Julian date in the requested timescale.

See also: jd_day(), mjd()

References novas_get_time().

Referenced by Time(), Time(), supernovas::Equinox::cirs(), day_of_week(), epoch(), supernovas::Orbital::from_mean_motion(), supernovas::SolarSystemSource::helio_distance(), supernovas::SolarSystemSource::helio_rate(), supernovas::Equinox::mod(), supernovas::Orbital::moon_mean_orbit_at(), supernovas::Orbital::moon_orbit_at(), moon_phase(), next_moon_phase(), supernovas::OrbitalSystem::orbit(), supernovas::Planet::orbit(), supernovas::Orbital::position(), supernovas::SolarSystemSource::solar_power(), to_calendar_date(), supernovas::Ecliptic::to_mod(), supernovas::Horizontal::to_refracted(), supernovas::Ecliptic::to_tod(), supernovas::Horizontal::to_unrefracted(), supernovas::Equinox::tod(), and supernovas::Orbital::velocity().

◆ jd_day()

long supernovas::Time::jd_day ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the integer Julian day of this time instance, in the specific timescale of choice.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the integer Julian day in the requested timescale.

See also: jd_frac(), mjd_day(), mjd(), jd()

References novas_get_split_time(), and NOVAS_TIMESCALES.

◆ jd_frac()

double supernovas::Time::jd_frac ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the factional Julian Day (MJD) of this time instance, in the specific timescale of choice.

0h in Julian dates is at noon.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the fractional part of the Julian Day in the requested timescale.

See also: mjd_frac(), jd_day(), jd()

References novas_get_split_time(), and NOVAS_TIMESCALES.

Referenced by mjd_frac().

◆ leap_seconds()

int supernovas::Time::leap_seconds ( ) const

Returns the leap seconds for this time instance, as was provided during instantiation.

Returns: [s] the leap seconds (TAI - UTC).

See also: dUT1()

References novas_time_leap().

Referenced by Time(), Time(), Time(), Time(), Time(), Time(), Time(), Time(), from_mjd(), next_moon_phase(), operator-(), and shifted().

◆ lst()

TimeAngle supernovas::Time::lst	(	const Site &	site,
		enum novas_accuracy	accuracy = NOVAS_FULL_ACCURACY ) const

Returns the Local (Apparent) Sidereal Time for this time instance.

Parameters

site	observing site
accuracy	(optional) NOVAS_FULL_ACCURACY (0; default) for μs-level precision or NOVAS_REDUCED_ACCURACY (1) for &ms-level precison.

Returns: the LST / LaST time-angle.

See also: gst(), era()

References supernovas::Angle::deg(), supernovas::Unit::hour_angle, supernovas::Validating::is_valid(), supernovas::Site::longitude(), and novas_time_lst().

◆ mjd()

double supernovas::Time::mjd ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the precise Modified Julian Date (MJD) this time instance, in the specific timescale of choice.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the precise Modifie Julian Date (MJD) in the requested timescale.

See also: mjd_day(), jd()

References novas_get_split_time(), NOVAS_JD_MJD0, and NOVAS_TIMESCALES.

Referenced by from_mjd(), from_mjd(), and operator-().

◆ mjd_day()

long supernovas::Time::mjd_day ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the integer Modified Julian Day (MJD) of this time instance, in the specific timescale of choice.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the integer Modified Julian Day (MJD) in the requested timescale.

See also: jd_frac(), jd_day(), mjd(), jd()

References novas_get_split_time(), and NOVAS_TIMESCALES.

◆ mjd_frac()

double supernovas::Time::mjd_frac ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the integer Modified Julian Day (MJD) of this time instance, in the specific timescale of choice.

0h in MJD is at midnight.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: [day] the fractional part of the Julian Day in the requested timescale.

See also: jd_frac(), mjd_day(), mjd()

References jd_frac(), and NOVAS_TIMESCALES.

Referenced by time_of_day().

◆ moon_phase()

Angle supernovas::Time::moon_phase ( ) const

Returns the phase of the Moon at this time instance.

Returns: The Moon's phase, or more precisely the ecliptic longitude difference between the Sun and the Moon, as seen from the geocenter. 0°: New Moon, 90°: 1st quarter, +/- 180° Full Moon, -90°: 3rd quarter, or NAN if the solution failed to converge (errno will be set to ECANCELED).

See also: next_moon_phase()

References supernovas::Unit::deg, supernovas::Validating::is_valid(), jd(), novas_moon_phase(), and NOVAS_TDB.

◆ next_moon_phase()

Time supernovas::Time::next_moon_phase ( const Angle & phase ) const

Returns the next time, after this time instance, when the Moon will be in the specified phase.

Parameters

phase The Moon's phase. 0°: New Moon, 90°: 1st quarter, +/- 180° Full Moon, -90°: 3rd quarter.

Returns: The next time the Moon will be in the specified phase.

See also: moon_phase()

References supernovas::Angle::deg(), dUT1(), supernovas::Validating::is_valid(), jd(), leap_seconds(), novas_next_moon_phase(), and NOVAS_TDB.

◆ now()

Time supernovas::Time::now ( const EOP & eop )

static

Resturns a new astrometric time instance for the current time.

It is only as accurate as the system clock, and its precision may be limited by the resolution of the system clock also. Be sure that your computer is well synchronized to a trustworthy time server, preferably on a local network, such as an ntp server with a GPS receiver.

Parameters

eop	Earth Orientation Parameters (EOP) values, e.g. obtained from IERS.

Returns: a new astrometric time corresponding to the current system time.

See also: Time(), from_mjd(), j2000(), b1950(), b1900(), hip()

References supernovas::EOP::dUT1(), supernovas::Validating::is_valid(), supernovas::EOP::leap_seconds(), novas_set_current_time(), and supernovas::Interval::seconds().

◆ offset_from()

Interval supernovas::Time::offset_from	(	const Time &	time,
		enum novas_timescale	timescale = NOVAS_TT ) const

Returns the difference of this time from the specified other time, in the specified timescale.

All timescales are supported.

Parameters

Time of observation and astronomical timescales	the other time
timescale	(optional) the timescale in which to return the result (default: TT).

Returns: the difference between this time and the argument time in the specified timescale.

operator-(), shifted()

References supernovas::Validating::is_valid(), and novas_diff_time_scale().

Referenced by operator-().

◆ operator!=()

bool supernovas::Time::operator!= ( const Time & time ) const

Checks if this time instance differs from another time by more than 1 μs.

Parameters

Time of observation and astronomical timescales the other time

Returns: true if the two times differ by more than 1 μs.

See also: operator==(), operator!=()

References equals().

◆ operator+() [1/2]

Time supernovas::Time::operator+ ( const Interval & offset ) const

Returns an offset time in the backward direction.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

offset the offset interval (in backwards direction).

Returns: a new time that is offset from this one by the specified interval.

See also: oerator-(), shifted()

References supernovas::Interval::seconds().

◆ operator+() [2/2]

Time supernovas::Time::operator+ ( double seconds ) const

Returns an offset time.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

seconds [s] the offset interval

Returns: a new time that is offset from this one by the specified interval in the reverse direction (backwards in time).

See also: oerator+(), shifted()

References shifted().

◆ operator-() [1/4]

Interval supernovas::Time::operator- ( const CalendarDate & other ) const

References supernovas::Calendar::astronomical(), dUT1(), leap_seconds(), mjd(), NOVAS_FULL_ACCURACY, NOVAS_TT, NOVAS_UTC, and supernovas::Unit::us.

◆ operator-() [2/4]

Time supernovas::Time::operator- ( const Interval & offset ) const

Returns an offset time.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

offset the offset interval

Returns: a new time that is offset from this one by the specified interval in the reverse direction (backwards in time).

See also: operator+(), shifted()

References supernovas::Interval::seconds().

◆ operator-() [3/4]

Interval supernovas::Time::operator- ( const Time & r ) const

Returns the difference of this time from the specified other time, in regular Earth-based time measures (GPS, TAI, TT – and also UTC assuming no change in leap seconds).

Parameters

r	the other time

Returns: the difference between this time and the argument in regular Earth-based timescales.

offset_from()

References supernovas::Validating::is_valid(), and offset_from().

◆ operator-() [4/4]

Time supernovas::Time::operator- ( double seconds ) const

Returns an offset time in the backwards direction.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

seconds [s] the offset interval (backwards direction).

Returns: a new time that is offset from this one by the specified interval in the reverse direction (backwards in time).

See also: oerator+(), shifted()

References shifted().

◆ operator<()

bool supernovas::Time::operator< ( const Time & r ) const

Checks if this time is prior to the specified other time, at the full precision of the representation.

Parameters

r	the other time

Returns: true if this time instance is before the specified other time, or else false.

See also: operator<=(), operator>(), operator>=()

References novas_diff_time().

◆ operator<=()

bool supernovas::Time::operator<= ( const Time & r ) const

Checks if this time is the same as or before the specified other time, at 1 μs resolution.

Parameters

r	the other time

Returns: true if this time instance is the same as or before the specified other time, or else false.

See also: operator<(), operator>=(), operator>()

References novas_diff_time(), and supernovas::Unit::us.

◆ operator==()

bool supernovas::Time::operator== ( const Time & time ) const

Checks if this time instance is the same as another time within 1 μs.

Parameters

Time of observation and astronomical timescales the other time

Returns: true if the two times are equal within 1 μs, otherwise false.

See also: equals(), operator!=()

References equals().

◆ operator>()

bool supernovas::Time::operator> ( const Time & r ) const

Checks if this time is after to the specified other time, at the full precision of the representation.

Parameters

r	the other time

Returns: true if this time instance is after the specified other time, or else false.

See also: operator>=(), operator<(), operator<=()

◆ operator>=()

bool supernovas::Time::operator>= ( const Time & r ) const

Checks if this time is the same as or after the specified other time, at 1 μs resolution.

Parameters

r	the other time

Returns: true if this time instance is the same as or after the specified other time, or else false.

See also: operator<(), operator>=(), operator>()

◆ shifted() [1/2]

Time supernovas::Time::shifted	(	const Interval &	offset,
		enum novas_timescale	timescale = NOVAS_TT ) const

Returns an offset time.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

offset	the offset interval in a regular Earth-based timescale (GPS, TAI, TT – or UTC assuming no change in leap seconds).
timescale	(optional) timescale in which offset time is given (default: TT / TAI / GPS).

Returns: a new time that is offset from this one by the specified interval in the specified timescale

See also: oerator+(), offset_from()

References supernovas::Interval::seconds(), and shifted().

◆ shifted() [2/2]

Time supernovas::Time::shifted	(	double	seconds,
		enum novas_timescale	timescale = NOVAS_TT ) const

Returns an offset time.

It assumes that the leap seconds and UT1 - UTC time difference of this time instance is also valid for the offset time, which should be true typically for reasonably small time offsets.

Parameters

seconds	[s] the offset interval in a regular Earth-based timescale (GPS, TAI, TT – or UTC assuming no change in leap seconds).
timescale	(optional) timescale in which offset time is given (default: TT / TAI / GPS).

Returns: a new time that is offset from this one by the specified interval in the specified timescale.

See also: oerator+(), offset_from()

References supernovas::Unit::day, dUT1(), supernovas::Validating::is_valid(), leap_seconds(), novas_get_split_time(), novas_set_split_time(), and undefined().

Referenced by operator+(), operator-(), and shifted().

◆ time_of_day()

TimeAngle supernovas::Time::time_of_day ( enum novas_timescale timescale = NOVAS_TT ) const

Returns the time of (calendar) day of this time instance in the timescale of choice.

Parameters

timescale (optional) the timescale in which to return the result (default: TT).

Returns: The time of day in the requested timescale.

See also: jd_time_of_day()

References supernovas::Validating::is_valid(), mjd_frac(), and TWOPI.

◆ to_calendar_date() [1/2]

CalendarDate supernovas::Time::to_calendar_date	(	const Calendar &	calendar = Calendar::astronomical(),
		enum novas_timescale	timescale = NOVAS_UTC ) const

Returns a calendar date, in the calendar of choice, and in the timescale of choice, for time instance.

Parameters

calendar	(optional) Calendar in which to represent this time instance (default: astronomical)
timescale	(optional) timescale in which MJD was specified (default: TT)

Returns: the calendar date in the desired calendar and timescale of choice.

References supernovas::Calendar::date(), supernovas::Validating::is_valid(), and jd().

Referenced by to_calendar_date().

◆ to_calendar_date() [2/2]

CalendarDate supernovas::Time::to_calendar_date ( enum novas_timescale timescale ) const

Returns the astronomical calendar date instance for this astrometric time.

The astronomical calendar is the conventional calendar of date, which is the Gregorian calendar after the Gregorian calendar reform if 1582, and the Roman calendar prior to that.

Parameters

timescale timescale in which MJD was specified (default: TT)

Returns: the astronomical calendar date in the timescale of choice.

References supernovas::Calendar::astronomical(), and to_calendar_date().

◆ to_epoch_string()

std::string supernovas::Time::to_epoch_string ( int decimals = 2 ) const

Returns the string representation of the Julian coordinate epoch corresponding to this timestamp.

Parameters

decimals (optional) number of decimal places to show on the year (default: 2).

Returns: a new string representing the Julian coordinate epoch of this time with the requested precision, or "<invalid epoch>"

References epoch(), and supernovas::Validating::is_valid().

◆ to_iso_string()

std::string supernovas::Time::to_iso_string ( ) const

Returns an ISO 8601 timestamp for this time instance.

Returns: a new string containing the ISO 8601 timestamp, or "<invalid time>".

See also: to_string()

References supernovas::Validating::is_valid(), and novas_iso_timestamp().

◆ to_string()

std::string supernovas::Time::to_string ( enum novas_timescale timescale = NOVAS_UTC ) const

Returns a string representation (a timestamp) of this time instance.

Parameters

timescale (optional) the timescale in which to represent time (default: UTC).

Returns: a new string containing the timestamp, or "<invalid time>".

See also: to_iso_timestamp(), to_epoch_string()

References supernovas::Validating::is_valid(), and novas_timestamp().

◆ undefined()

const Time & supernovas::Time::undefined ( )

static

Returns a reference to a statically defined standard invalid astrometric time.

This invalid time may be used inside any object that is invalid itself.

Returns: a reference to a static standard invalid astrometric time.

Referenced by shifted().

◆ unix_time()

time_t supernovas::Time::unix_time ( long * nanos = NULL ) const

Returns the precise UNIX time (UTC) corresponding to this time instance.

Parameters

[out] nanos [ns] (optional) pointer to value in which to return the sub-second component, or NULL if not required.

Returns: [s] the integer UNIX seconds (UTC) of this time instance.

References novas_get_unix_time().

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Time() [1/9]

◆ Time() [2/9]

◆ Time() [3/9]

◆ Time() [4/9]

◆ Time() [5/9]

◆ Time() [6/9]

◆ Time() [7/9]

◆ Time() [8/9]

◆ Time() [9/9]

Member Function Documentation

◆ _novas_timespec()

◆ b1900()

◆ b1950()

◆ day_of_week()

◆ dUT1()

◆ epoch()

◆ equals() [1/2]

◆ equals() [2/2]

◆ era()

◆ from_mjd() [1/2]

◆ from_mjd() [2/2]

◆ gmst()

◆ gst()

◆ hip()

◆ j2000()

◆ jd()

◆ jd_day()

◆ jd_frac()

◆ leap_seconds()

◆ lst()

◆ mjd()

◆ mjd_day()

◆ mjd_frac()

◆ moon_phase()

◆ next_moon_phase()

◆ now()

◆ offset_from()

◆ operator!=()

◆ operator+() [1/2]

◆ operator+() [2/2]

◆ operator-() [1/4]

◆ operator-() [2/4]

◆ operator-() [3/4]

◆ operator-() [4/4]

◆ operator<()

◆ operator<=()

◆ operator==()

◆ operator>()

◆ operator>=()

◆ shifted() [1/2]

◆ shifted() [2/2]

◆ time_of_day()

◆ to_calendar_date() [1/2]

◆ to_calendar_date() [2/2]

◆ to_epoch_string()

◆ to_iso_string()

◆ to_string()

◆ undefined()

◆ unix_time()