Date.h File Reference

Generic timing routines. More...

#include "CUtils.h"
#include "LeapSeconds.h"

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Macros
#define	EPOCH_GPS_TAI_UTC   19
	Leap seconds (TAI-UTC) on the GPS epoch (1980 JAN 6 0h UTC) *‍/.
#define	EPOCH_J2000_0_JD   2451545.0
	Julian Day of the J2000.0 epoch (2000 JAN 1 12h UTC).
#define	EPOCH_UNIX_GPS   315964800
#define	M_C   299792458.0
	Speed of light.

Functions
string	GetTimeStampFromGps (const unsigned int aGps)
	Returns the time stamp from a GPS time.
struct tm *	GPSToUTC (struct tm *aUtc, unsigned int aGps)
	Returns a pointer to a tm structure representing the time specified in seconds since the GPS epoch.
double	GreenwichMeanSiderealTime (const double aGps)
	Returns the Greenwich Mean Sidereal Time in RADIANS for a specified GPS time.
double	GreenwichSiderealTime (const double aGps, const double aEquationOfEquinoxes)
	Returns the Greenwich mean or aparent sideral time in radians.
double	JulianDay (const struct tm *aUtc)
	Returns the Julian Day (JD) corresponding to the date given in a broken down time structure.
int	LeapSeconds (const unsigned int aGps)
	Returns the leap seconds TAI-UTC at a given GPS second.
int	LeapSecondsUTC (const struct tm *aUtc)
	Returns the leap seconds TAI-UTC for a given UTC broken down time.
unsigned int	UTCToGPS (const struct tm *aUtc)
	Returns the GPS seconds for a specified UTC time structure.

Detailed Description

Generic timing routines.

Author

Karl Wette, Duncan Brown, David Chin, Jolien Creighton, Kipp Cannon, Reinhard Prix, Stephen Fairhurst, Florent Robinet

Macro Definition Documentation

EPOCH_GPS_TAI_UTC

#define EPOCH_GPS_TAI_UTC   19

Leap seconds (TAI-UTC) on the GPS epoch (1980 JAN 6 0h UTC) *‍/.

EPOCH_J2000_0_JD

#define EPOCH_J2000_0_JD   2451545.0

Julian Day of the J2000.0 epoch (2000 JAN 1 12h UTC).

EPOCH_UNIX_GPS

#define EPOCH_UNIX_GPS   315964800

M_C

#define M_C   299792458.0

Speed of light.

Function Documentation

GetTimeStampFromGps()

string GetTimeStampFromGps

(

const unsigned int

aGps

)

Returns the time stamp from a GPS time.

Format: "%Y-%b-%d %H:%M:%S"

Parameters

[in]

aGps

GPS time [s].

GPSToUTC()

struct tm * GPSToUTC	(	struct tm *	aUtc,
		unsigned int	aGps
	)

Returns a pointer to a tm structure representing the time specified in seconds since the GPS epoch.

Parameters

[out]	aUtc	Pointer to a time structure.
[in]	aGps	GPS time [s].

GreenwichMeanSiderealTime()

double GreenwichMeanSiderealTime

(

const double

aGps

)

Returns the Greenwich Mean Sidereal Time in RADIANS for a specified GPS time.

Convenience wrapper, calling GreenwichSiderealTime() with the equation of equinoxes set to 0.

Parameters

[in]

aGps

GPS time [s].

GreenwichSiderealTime()

double GreenwichSiderealTime	(	const double	aGps,
		const double	aEquationOfEquinoxes
	)

Returns the Greenwich mean or aparent sideral time in radians.

Aparent sidereal time is computed by providing the equation of equinoxes in units of seconds. For mean sidereal time, set this parameter to 0.

This function returns the sidereal time in radians measured from the Julian epoch (current J2000). The result is NOT modulo 2 pi.

Inspired by the function sidereal_time() in the NOVAS-C library, version 2.0.1, which is dated December 10th, 1999, and carries the following references:

Aoki, et al. (1982) Astronomy and Astrophysics 105, 359-361. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.

See also

http://aa.usno.navy.mil/software/novas for more information.

Parameters

[in]	aGps	GPS time [s].
[in]	aEquationOfEquinoxes	Equation of equinoxes in [s]. For mean sidereal time, set this parameter to 0.

JulianDay()

double JulianDay

(

const struct tm *

aUtc

)

Returns the Julian Day (JD) corresponding to the date given in a broken down time structure.

Parameters

[in]

aUtc

Pointer to a time structure.

LeapSeconds()

int LeapSeconds

(

const unsigned int

aGps

)

Returns the leap seconds TAI-UTC at a given GPS second.

Parameters

[in]

aGps

GPS time [s].

LeapSecondsUTC()

int LeapSecondsUTC

(

const struct tm *

aUtc

)

Returns the leap seconds TAI-UTC for a given UTC broken down time.

Parameters

[in]

aUtc

Pointer to a time structure.

UTCToGPS()

unsigned int UTCToGPS

(

const struct tm *

aUtc

)

Returns the GPS seconds for a specified UTC time structure.

Parameters

[in]

aUtc

Pointer to a time structure.