public void FindInstantBesselianElements()
{
// 11 Aug 1999, 11:00:00 TDT
// Besselian elements are taken from
// https://eclipse.gsfc.nasa.gov/SEsearch/SEdata.php?Ecl=+19990811
// Sun and Moon geocentric positions are taken
// from NASA horizons tool
// https://ssd.jpl.nasa.gov/horizons.cgi
var position = new SunMoonPosition()
{
JulianDay = 2451401.958333333,
Sun = new CrdsEquatorial(new HMS("09h 23m 11.27s"), new DMS("+15* 19' 30.1''")),
Moon = new CrdsEquatorial(new HMS("09h 23m 30.71s"), new DMS("+15* 48' 50.3''")),
DistanceSun = 1.5162934697E+08 / 6371.0,
DistanceMoon = 3.7330565613E+05 / 6371.0
};
var elements = SolarEclipses.BesselianElements(position);
Assert.AreEqual(15.32734, elements.D, 1e-2);
Assert.AreEqual(343.68741, elements.Mu, 1e-1);
Assert.AreEqual(0.070042, elements.X, 1e-2);
Assert.AreEqual(0.502841, elements.Y, 1e-2);
Assert.AreEqual(0.542469, elements.L1, 1e-2);
Assert.AreEqual(-0.003650, elements.L2, 1e-2);
}
void ResetTime(DateTime dateTime)
{
var tz = mapOrigin.TimeZone;
var utcMidnight = TimeZoneInfo.ConvertTimeToUtc(new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, DateTimeKind.Unspecified), tz);
jday = SunMoonPosition.GetJulianDayFromGregorianDateTime(utcMidnight);
SunMoonPosition.GetSunRiseSet(tz, dateTime, gpsLocation.Longitude, gpsLocation.Latitude, out sunRiseBegin, out sunRiseEnd, out sunSetBegin, out sunSetEnd);
currentTimeOfDay = (float)dateTime.TimeOfDay.TotalHours;
currentTimeOfDayCycle = TimeOfDayCycleTypes.Freeze;
}
private void ResetTime(DateTime dateTime)
{
var tz = MapOrigin.TimeZone;
var utcMidnight = TimeZoneInfo.ConvertTimeToUtc(new DateTime(dateTime.Year, dateTime.Month, dateTime.Day, 0, 0, 0, DateTimeKind.Unspecified), tz);
JDay = SunMoonPosition.GetJulianDayFromGregorianDateTime(utcMidnight);
SunMoonPosition.GetSunRiseSet(tz, dateTime, GPSLocation.Longitude, GPSLocation.Latitude, out SunRiseBegin, out SunRiseEnd, out SunSetBegin, out SunSetEnd);
CurrentDateTime = dateTime;
CurrentTimeOfDay = (float)dateTime.TimeOfDay.TotalHours;
CurrentTimeOfDayCycle = TimeOfDayCycleTypes.Freeze;
UpdateDistributedState();
}
/// <summary>
/// Calculates solar and lunar positions at five uniformly spaced times
/// over a specified period centered at t0, where t0 is an integer hour of day
/// nearest to the specified time instant of eclipse maximum.
/// </summary>
/// <param name="jdMaximum">Instant of eclipse maximum.</param>
/// <param name="period">Period, in hours.</param>
/// <returns></returns>
private SunMoonPosition[] GetSunMoonPositions(double jdMaximum, double period)
{
// found t0 (nearest integer hour closest to the eclipse maximum)
double t0;
Date d = new Date(jdMaximum);
if (d.Minute < 30)
{
t0 = jdMaximum - new TimeSpan(0, d.Minute, d.Second).TotalDays;
}
else
{
t0 = jdMaximum - new TimeSpan(0, d.Minute, d.Second).TotalDays + TimeSpan.FromHours(1).TotalDays;
}
// The Besselian elements are derived from a least-squares fit to elements
// calculated at five uniformly spaced times over a period centered at t0.
SunMoonPosition[] pos = new SunMoonPosition[5];
double dt = TimeSpan.FromHours(period / 2).TotalDays;
double step = TimeSpan.FromHours(period / 4).TotalDays;
string[] ephemerides = new[] { "Equatorial0.Alpha", "Equatorial0.Delta", "Distance" };
var sunEphem = sky.GetEphemerides(sun, t0 - dt, t0 + dt + 1e-6, step, ephemerides);
var moonEphem = sky.GetEphemerides(moon, t0 - dt, t0 + dt + 1e-6, step, ephemerides);
// astronomical unit, in km
const double AU = 149597870;
// earth radius, in km
const double EARTH_RADIUS = 6371;
for (int i = 0; i < 5; i++)
{
pos[i] = new SunMoonPosition()
{
JulianDay = t0 + step * (i - 2),
Sun = new CrdsEquatorial(sunEphem[i].GetValue <double>("Equatorial0.Alpha"), sunEphem[i].GetValue <double>("Equatorial0.Delta")),
Moon = new CrdsEquatorial(moonEphem[i].GetValue <double>("Equatorial0.Alpha"), moonEphem[i].GetValue <double>("Equatorial0.Delta")),
DistanceSun = sunEphem[i].GetValue <double>("Distance") * AU / EARTH_RADIUS,
DistanceMoon = moonEphem[i].GetValue <double>("Distance") / EARTH_RADIUS
};
}
return(pos);
}
private void UpdateSunPosition()
{
sun.transform.rotation = SunMoonPosition.GetSunPosition(jday + currentTimeOfDay / 24f, gpsLocation.Longitude, gpsLocation.Latitude);
}
private void UpdateMoonPosition()
{
Moon.transform.localRotation = SunMoonPosition.GetMoonPosition(JDay + CurrentTimeOfDay / 24f, GPSLocation.Longitude, GPSLocation.Latitude);
}
