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/***************************************************************************
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() );
}
}
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