AstroTime Class Reference

Encapsulates a few time properties which are astronomically relevant. More...

#include <astrotime.h>

Public Member Functions
const double	gmst_2pi (void) const
	The following calculates GMST of date, in radians. More...
const double	lmst (void) const
	Returns the Local Mean Sidereal Time at the observatory.
const double	ut1 (void) const
	Return UT1 as a number of hours. More...
const int	mjd (void) const
	Return the MJD at time 00:00 on the indicated day. More...
	AstroTime ()
	The default constructor produces a valid, but largely useless structure, representing midnight on 1858 November 17 (MJD=0) at the meridian.
	AstroTime (const int year, const int month, const int day, const int hour, const int minute, const double second, const double obslong)
	Create a new time. More...
	AstroTime (const AstroTime &ref, const double extra_secs)
	Return a new astrotime, with the time given by the tm struct. More...
	AstroTime (const int year, const int month, const int day)
	Create a new time. More...
AstroTime	move (double obs_lon)
	Return a new AstroTime representing the same UT as this one, but for a different observatory longitude. More...
char *	str (char *, size_t)
	Format the current time into the given buffer. More...

Detailed Description

Encapsulates a few time properties which are astronomically relevant.

Constructor & Destructor Documentation

AstroTime::AstroTime	(	const int	year,
		const int	month,
		const int	day,
		const int	hour,
		const int	minute,
		const double	second,
		const double	obslong
	)

Create a new time.

The time must be given in UT1.

Parameters

year	must be after 1859 (ie, positive MJD)
month	month in [1, 12]
day	day in [1, 31]
hour	UT1 hour, positive
minute	UT1 minute, positive
second	UT1 second, positive
obslong	the observatory east-longitude, in radians

AstroTime::AstroTime	(	const AstroTime &	ref,
		const double	extra_secs
	)

Return a new astrotime, with the time given by the tm struct.

Returns a new time, offset from the reference time by a number of UT1 seconds.

AstroTime::AstroTime	(	const int	year,
		const int	month,
		const int	day
	)

Create a new time.

The time is given in LST on the supplied date. LST must be supplied in radians in the range [0,2pi). Create a new time, defaulting to noon.

Member Function Documentation

const double AstroTime::gmst_2pi

(

void

)

const

The following calculates GMST of date, in radians.

This evaluates the expression for GMST in terms of UT, as given in Explanatory Supplement Eq.2.24-1, but with the resulting time normalised to be in [0,2pi)

const int AstroTime::mjd

(

void

)

const

Return the MJD at time 00:00 on the indicated day.

This is a round number.

AstroTime AstroTime::move

(

double

new_obs_lon

)

Return a new AstroTime representing the same UT as this one, but for a different observatory longitude.

Parameters

new_obs_lon

the observatory east-longitude, in radians

char * AstroTime::str	(	char *	buf,
		size_t	buflen
	)

Format the current time into the given buffer.

Parameters

buf	a buffer to receive the formatted string
buflen	the size of this buffer; if the string would be longer than this it is truncated

const double AstroTime::ut1

(

void

)

const

Return UT1 as a number of hours.

The result is always in the range [0, 24).

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The documentation for this class was generated from the following files:

• astrotime.h
• astrotime.cpp