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/***************************************************************************
kstarsdatetime.h - Trinity Desktop Planetarium
-------------------
begin : Tue 05 May 2004
copyright : (C) 2001 by Jason Harris
email : jharris@30doradus.org
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef KSTARSDATETIME_H
#define KSTARSDATETIME_H
#define J2000 2451545.0 //Julian Date for noon on Jan 1, 2000 (epoch J2000)
//defined here because this file is included in every other class.
#define B1950 2433282.4235 // Julian date for Jan 0.9235, 1950
#define SIDEREALSECOND 1.002737909 //number of sidereal seconds in one solar second
#include "libtdeedu/extdate/extdatetime.h"
class dms;
/**@class KStarsDateTime
*@short Extension of ExtDateTime for KStars
*Instead of an integer Julian Day, KStarsDateTime uses a long double Julian Day,
*in which the fractional portion encodes the time of day to a precision of a less than a second.
*Also adds Greenwich Sidereal Time.
*@note Local time and Local sideral time are not handled here. Because they depend on the
*geographic location, they are part of the GeoLocation class.
*@sa GeoLocation::GSTtoLST()
*@sa GeoLocation::UTtoLT()
*@author Jason Harris
*@version 1.0
*/
class KStarsDateTime : public ExtDateTime
{
public:
/**
*@short Default constructor
*Creates a date/time at J2000 (noon on Jan 1, 200)
*/
KStarsDateTime();
/**
*@short Constructor
*Creates a date/time at the specified Julian Day.
*@p jd The Julian Day
*@note this is overloaded from ExtDateTime. It does not allow for assigning the
*time of day, because the jd argument is an integer
*/
KStarsDateTime( long int jd );
/**
*@short Constructor
*Creates a date/time at the specified Julian Day.
*@p jd The Julian Day
*/
KStarsDateTime( double djd );
/**
*@short Constructor
*Creates a date/time at the specified Julian Day.
*@p jd The Julian Day
*/
KStarsDateTime( long double djd );
/**
*@short Copy constructor
*@p kdt The KStarsDateTime object to copy.
*/
KStarsDateTime( const KStarsDateTime &kdt );
/**
*@short Copy constructor
*@p kdt The ExtDateTime object to copy.
*/
KStarsDateTime( const ExtDateTime &kdt );
/**
*@short Constructor
*Create a KStarsDateTimne based on the specified Date and Time.
*@p _d The ExtDate to assign
*@p _t The TQTime to assign
*/
KStarsDateTime( const ExtDate &_d, const TQTime &_t );
/**
*Assign the (long double) Julian Day value, which includes the time of day
*encoded in the fractional portion.
*@p jd the Julian Day value to assign.
*/
void setDJD( long double jd );
/**
*Assign the Date according to an ExtDate object.
*@p d the ExtDate to assign
*/
void setDate( const ExtDate &d );
/**
*Assign the Time according to a TQTime object.
*@p t the TQTime to assign
*/
void setTime( const TQTime &t );
/**
*Modify the Date/Time by adding a number of seconds.
*@p s the number of seconds to add. The number can be negative.
*/
KStarsDateTime addSecs( long double s ) const { return KStarsDateTime( djd() + s/86400. ); }
/**
*Modify the Date/Time by adding a number of days.
*@p nd the number of days to add. The number can be negative.
*/
KStarsDateTime addDays( int nd ) const { return KStarsDateTime( djd() + (long double)nd ); }
bool operator == ( const KStarsDateTime &d ) const { return DJD == d.djd(); }
bool operator != ( const KStarsDateTime &d ) const { return DJD != d.djd(); }
bool operator < ( const KStarsDateTime &d ) const { return DJD < d.djd(); }
bool operator <= ( const KStarsDateTime &d ) const { return DJD <= d.djd(); }
bool operator > ( const KStarsDateTime &d ) const { return DJD > d.djd(); }
bool operator >= ( const KStarsDateTime &d ) const { return DJD >= d.djd(); }
/**
*@return the date and time according to the CPU clock (note that this is not
*necessarily UT)
*/
static KStarsDateTime currentDateTime();
/**
*@return the julian day as a long double, including the time as the fractional portion.
*/
long double djd() const { return DJD; }
/**
*@return the fraction of the Julian Day corresponding to the current time.
*Because the integer Julian Day value jd() is referenced to Noon on the current date,
*jdFrac() ranges between values of -0.5 and +0.5 for the previous and next midnights,
*respectively.
*/
double jdFrac() const { return ((time().hour()-12) + (time().minute()
+ (time().second() + time().msec()/1000.)/60.)/60.)/24.; }
/**
*@return the Julian Day value for the current date, but at 0h UT.
*@note the returned value is always an integer value + 0.5.
*/
long double JDat0hUT() const { return int( djd() - 0.5 ) + 0.5; }
/**
*@return The Greenwich Sidereal Time
*The Greenwich sidereal time is the Right Ascension coordinate that is currently transiting
*the Prime Meridian at the Royal Observatory in Greenwich, UK (longitude=0.0)
*/
dms gst() const;
/**
*Convert a given Greenwich Sidereal Time to Universal Time (=Greenwich Mean Time).
*@p GST the Greenwich Sidereal Time to convert to Universal Time.
*/
TQTime GSTtoUT( dms GST ) const;
/**
*@return the epoch value of the Date/Time.
*@note the epoch is shorthand for the date, expressed as a floating-point year value.
*@sa setFromEpoch()
*/
double epoch() const { return ( double( date().year() )
+ double( date().dayOfYear() )/double( date().daysInYear() ) ); }
/**
*Set the Date/Time from an epoch value.
*@p e the epoch value
*@sa epoch()
*/
void setFromEpoch( double e );
private:
/**
*@return the Greenwich Sidereal Time at 0h UT on this object's Date
*@note used internally by gst() and GSTtoUT()
*/
dms GSTat0hUT() const;
long double DJD;
};
#endif //KSTARSDATETIME_H
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