public static double GetSunLongitude(GregorianDateTime vct, GCEarthData earth)
{
switch (System)
{
case AstronomySystem.Meeus:
return(GCSunData.GetSunLongitude(vct));
}
return(0);
}
///////////////////////////////////////////////////////////////////////
// GET PREVIOUS CONJUNCTION OF THE SUN AND MOON
//
// THIS IS HELP FUNCTION FOR GetPrevConjunction(VCTIME test_date,
// VCTIME &found, bool this_day, EARTHDATA earth)
//
// looking for previous sun-moon conjunction
// it starts from input day from 12:00 AM (noon) UTC
// so output can be the same day
// if output is the same day, then conjunction occurs between 00:00 AM and noon of this day
//
// date - input / output
// earth - input
// return value - sun longitude in degs
//
// error is when return value is greater than 999.0 deg
public static double GetPrevConjunction(ref GregorianDateTime date, GCEarthData earth)
{
int bCont = 32;
double prevSun = 0.0, prevMoon = 0.0, prevDiff = 0.0;
double nowSun = 0.0, nowMoon = 0.0, nowDiff = 0.0;
// SUNDATA sun;
double jd, longitudeMoon;
GregorianDateTime d = new GregorianDateTime();
d.Set(date);
d.shour = 0.5;
d.TimezoneHours = 0.0;
jd = d.GetJulian();//GetJulianDay(d.year, d.month, d.day);
// set initial data for input day
// NOTE: for grenwich
//SunPosition(d, earth, sun);
longitudeMoon = GCCoreAstronomy.GetMoonLongitude(d, earth);
prevSun = GCSunData.GetSunLongitude(d);
prevMoon = longitudeMoon;
prevDiff = GCMath.putIn180(prevSun - prevMoon);
do
{
// shift to day before
d.PreviousDay();
jd -= 1.0;
// calculation
//SunPosition(d, earth, sun);
longitudeMoon = GCCoreAstronomy.GetMoonLongitude(d, earth);
nowSun = GCSunData.GetSunLongitude(d);
nowMoon = longitudeMoon;
nowDiff = GCMath.putIn180(nowSun - nowMoon);
// if difference of previous has another sign than now calculated
// then it is the case that moon was faster than sun and he
//printf(" prevsun=%f\nprevmoon=%f\nnowsun=%f\nnowmoon=%f\n", prevSun, prevMoon, nowSun, nowMoon);
if (IsConjunction(nowMoon, nowSun, prevSun, prevMoon))
{
// now it calculates actual time and zodiac of conjunction
double x;
if (prevDiff == nowDiff)
{
return(0);
}
x = Math.Abs(nowDiff) / Math.Abs(prevDiff - nowDiff);
if (x < 0.5)
{
d.shour = x + 0.5;
}
else
{
d.NextDay();
d.shour = x - 0.5;
}
date.Set(d);
double other = GCSunData.GetSunLongitude(d);
// double other2 = nowSun + (prevSun - nowSun)*x;
GCMath.putIn360(prevSun);
GCMath.putIn360(nowSun);
if (Math.Abs(prevSun - nowSun) > 10.0)
{
return(GCMath.putIn180(nowSun) + (GCMath.putIn180(prevSun) - GCMath.putIn180(nowSun)) * x);
}
else
{
return(nowSun + (prevSun - nowSun) * x);
}
// return other2;
}
prevSun = nowSun;
prevMoon = nowMoon;
prevDiff = nowDiff;
bCont--;
}while (bCont >= 0);
return(1000.0);
}
/*********************************************************************/
/* */
/* */
/* */
/* */
/* */
/*********************************************************************/
public static double GetNextConjunction(GregorianDateTime test_date, out GregorianDateTime found, bool this_conj, GCEarthData earth)
{
double phi = 12.0;
double l1, l2, longitudeSun, longitudeMoon;
if (this_conj)
{
test_date.shour += 0.2;
test_date.NormalizeValues();
}
double jday = test_date.GetJulianComplete();
double xj;
GregorianDateTime d = new GregorianDateTime();
d.Set(test_date);
GregorianDateTime xd = new GregorianDateTime();
double scan_step = 1.0;
int prev_tit = 0;
int new_tit = -1;
longitudeMoon = GCCoreAstronomy.GetMoonLongitude(d, earth);
longitudeSun = GCSunData.GetSunLongitude(d);
l1 = GCMath.putIn180(longitudeMoon - longitudeSun);
prev_tit = GCMath.IntFloor(l1 / phi);
int counter = 0;
while (counter < 20)
{
xj = jday;
xd.Set(d);
jday += scan_step;
d.shour += scan_step;
if (d.shour > 1.0)
{
d.shour -= 1.0;
d.NextDay();
}
longitudeMoon = GCCoreAstronomy.GetMoonLongitude(d, earth);
longitudeSun = GCSunData.GetSunLongitude(d);
l2 = GCMath.putIn180(longitudeMoon - longitudeSun);
new_tit = GCMath.IntFloor(l2 / phi);
if (prev_tit < 0 && new_tit >= 0)
{
jday = xj;
d.Set(xd);
scan_step *= 0.5;
counter++;
continue;
}
else
{
l1 = l2;
}
prev_tit = new_tit;
}
found = new GregorianDateTime();
found.Set(d);
return(longitudeSun);
}
