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Diffstat (limited to 'kstars/kstars/kstarsdatetime.cpp')
| -rw-r--r-- | kstars/kstars/kstarsdatetime.cpp | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/kstars/kstars/kstarsdatetime.cpp b/kstars/kstars/kstarsdatetime.cpp new file mode 100644 index 00000000..74d1fc20 --- /dev/null +++ b/kstars/kstars/kstarsdatetime.cpp @@ -0,0 +1,166 @@ + /*************************************************************************** + kstarsdatetime.cpp - K Desktop Planetarium + ------------------- + begin : Tue 05 May 2004 + copyright : (C) 2004 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. * + * * + ***************************************************************************/ + +#include <kdebug.h> + +#include "kstarsdatetime.h" +#include "ksnumbers.h" +#include "dms.h" + +KStarsDateTime::KStarsDateTime() : ExtDateTime() { + setDJD( J2000 ); +} + +KStarsDateTime::KStarsDateTime( long int _jd ) : ExtDateTime(){ + setDJD( (long double)( _jd ) ); +} + +KStarsDateTime::KStarsDateTime( const KStarsDateTime &kdt ) : ExtDateTime() { + setDJD( kdt.djd() ); +} + +KStarsDateTime::KStarsDateTime( const ExtDateTime &edt ) : ExtDateTime( edt ) { + //don't call setDJD() because we don't need to compute the time; just set DJD directly + QTime _t = edt.time(); + ExtDate _d = edt.date(); + long double jdFrac = ( _t.hour()-12 + ( _t.minute() + ( _t.second() + _t.msec()/1000.)/60.)/60.)/24.; + DJD = (long double)( _d.jd() ) + jdFrac; +} + +KStarsDateTime::KStarsDateTime( const ExtDate &_d, const QTime &_t ) : ExtDateTime( _d, _t ) { + //don't call setDJD() because we don't need to compute the time; just set DJD directly + long double jdFrac = ( _t.hour()-12 + ( _t.minute() + ( _t.second() + _t.msec()/1000.)/60.)/60.)/24.; + DJD = (long double)( _d.jd() ) + jdFrac; +} + +KStarsDateTime::KStarsDateTime( double _jd ) : ExtDateTime() { + setDJD( (long double)_jd ); +} + +KStarsDateTime::KStarsDateTime( long double _jd ) : ExtDateTime() { + setDJD( _jd ); +} + +KStarsDateTime KStarsDateTime::currentDateTime() { + KStarsDateTime dt( ExtDate::currentDate(), QTime::currentTime() ); + if ( dt.time().hour()==0 && dt.time().minute()==0 ) // midnight or right after? + dt.setDate( ExtDate::currentDate() ); // fetch date again + + return dt; +} + +void KStarsDateTime::setDJD( long double _jd ) { + DJD = _jd; + + ExtDate dd; + dd.setJD( (long int)( _jd + 0.5 ) ); + ExtDateTime::setDate( dd ); + + double dayfrac = _jd - (double)( date().jd() ) + 0.5; + if ( dayfrac > 1.0 ) dayfrac -= 1.0; + double hour = 24.*dayfrac; + int h = int(hour); + int m = int( 60.*(hour - h) ); + int s = int( 60.*(60.*(hour - h) - m) ); + int ms = int( 1000.*(60.*(60.*(hour - h) - m) - s) ); + + ExtDateTime::setTime( QTime( h, m, s, ms ) ); +} + +void KStarsDateTime::setDate( const ExtDate &_d ) { + //Save the JD fraction + long double jdFrac = djd() - (long double)( date().jd() ); + + //set the integer portion of the JD and add back the JD fraction: + setDJD( (long double)_d.jd() + jdFrac ); +} + +void KStarsDateTime::setTime( const QTime &_t ) { + KStarsDateTime _dt( date(), _t ); + setDJD( _dt.djd() ); +} + +dms KStarsDateTime::gst() const { + dms gst0 = GSTat0hUT(); + + double hr = double( time().hour() ); + double mn = double( time().minute() ); + double sc = double( time().second() ) + double ( 0.001 * time().msec() ); + double st = (hr + ( mn + sc/60.0)/60.0)*SIDEREALSECOND; + + dms gst = dms( gst0.Degrees() + st*15.0 ).reduce(); + return gst; +} + +dms KStarsDateTime::GSTat0hUT() const { + double sinOb, cosOb; + + // Mean greenwich sidereal time + KStarsDateTime t0( date(), QTime( 0, 0, 0 ) ); + long double s = t0.djd() - J2000; + double t = s/36525.0; + double t1 = 6.697374558 + 2400.051336*t + 0.000025862*t*t + + 0.000000002*t*t*t; + + // To obtain the apparent sidereal time, we have to correct the + // mean greenwich sidereal time with nutation in longitude multiplied + // by the cosine of the obliquity of the ecliptic. This correction + // is called nutation in right ascention, and may amount to 0.3 secs. + KSNumbers num( t0.djd() ); + num.obliquity()->SinCos( sinOb, cosOb ); + + // nutLong has to be in hours of time since t1 is hours of time. + double nutLong = num.dEcLong()*cosOb/15.0; + t1 += nutLong; + + dms gst; + gst.setH( t1 ); + return gst.reduce(); +} + +QTime KStarsDateTime::GSTtoUT( dms GST ) const { + dms gst0 = GSTat0hUT(); + + //dt is the number of sidereal hours since UT 0h. + double dt = GST.Hours() - gst0.Hours(); + while ( dt < 0.0 ) dt += 24.0; + while ( dt >= 24.0 ) dt -= 24.0; + + //convert to solar time. dt is now the number of hours since 0h UT. + dt /= SIDEREALSECOND; + + int hr = int( dt ); + int mn = int( 60.0*( dt - double( hr ) ) ); + int sc = int( 60.0*( 60.0*( dt - double( hr ) ) - double( mn ) ) ); + int ms = int( 1000.0*( 60.0*( 60.0*( dt - double(hr) ) - double(mn) ) - double(sc) ) ); + + return( QTime( hr, mn, sc, ms ) ); +} + +void KStarsDateTime::setFromEpoch( double epoch ) { + if (epoch == 1950.0) { + setDJD( 2433282.4235 ); + } else if ( epoch == 2000.0 ) { + setDJD( J2000 ); + } else { + int year = int( epoch ); + KStarsDateTime dt( ExtDate( year, 1, 1 ), QTime( 0, 0, 0 ) ); + double days = (double)(dt.date().daysInYear())*( epoch - (double)year ); + dt = dt.addSecs( days*86400. ); //set date and time based on the number of days into the year + setDJD( dt.djd() ); + } +} |