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