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