private static MoonPosition GetMoonPosition(DateTime date, double lat, double lng, Celestial cel)
{
//Set UTC date integrity
date = new DateTime(date.Year, date.Month, date.Day, date.Hour, date.Minute, date.Second, DateTimeKind.Utc);
double d = JulianConversions.GetJulian_Epoch2000(date);
//Ch 47
double JDE = JulianConversions.GetJulian(date); //Get julian
double T = (JDE - 2451545) / 36525; //Get dynamic time.
double[] LDMNF = Get_Moon_LDMNF(T);
CelCoords c = GetMoonCoords(d, cel, LDMNF, T);
Distance dist = GetMoonDistance(date);
double lw = rad * -lng;
double phi = rad * lat;
double H = rad * Get_Sidereal_Time(JDE, lw) - lw - c.ra;
double ra = c.ra; //Adjust current RA formula to avoid needless RAD conversions
double dec = c.dec; //Adjust current RA formula to avoid needless RAD conversions
//Adjust for parallax (low accuracry increases may not be worth cost)
//Investigate
double pSinE = Get_pSinE(dec, dist.Meters) * Math.PI / 180;
double pCosE = Get_pCosE(dec, dist.Meters) * Math.PI / 180;
double cRA = Parallax_RA(dist.Meters, H, pCosE, dec, ra);
double tDEC = Parallax_Dec(dist.Meters, H, pCosE, pSinE, dec, cRA);
double tRA = ra - cRA;
dec = tDEC;
ra = tRA;
//Get true altitude
double h = altitude(H, phi, dec);
// formula 14.1 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
double pa = Math.Atan2(Math.Sin(H), Math.Tan(phi) * Math.Cos(dec) - Math.Sin(dec) * Math.Cos(H));
//altitude correction for refraction
h = h + astroRefraction(h);
MoonPosition mp = new MoonPosition();
mp.Azimuth = azimuth(H, phi, dec);
mp.Altitude = h / Math.PI * 180;
mp.Distance = dist;
mp.ParallacticAngle = pa;
double horParal = 8.794 / (dist.Meters / 149.59787E6); // horizontal parallax (arcseconds), Meeus S. 263
double p = Math.Asin(Math.Cos(h) * Math.Sin(horParal / 3600)); // parallax in altitude (degrees)
p *= 1000;
mp.ParallaxCorection = p;
mp.Altitude *= rad;
return(mp);
}
static MoonPosition GetMoonPosition(DateTime date, double lat, double lng)
{
double d = toDays(date);
CelCoords c = GetMoonCoords(d);
double lw = rad * -lng;
double phi = rad * lat;
double H = siderealTime(d, lw) - c.ra;
double h = altitude(H, phi, c.dec);
// formula 14.1 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
double pa = Math.Atan2(Math.Sin(H), Math.Tan(phi) * Math.Cos(c.dec) - Math.Sin(c.dec) * Math.Cos(H));
h = h + astroRefraction(h); // altitude correction for refraction
MoonPosition mp = new MoonPosition();
mp.Azimuth = azimuth(H, phi, c.dec);
mp.Altitude = h;
mp.Distance = c.dist;
mp.ParallacticAngle = pa;
return(mp);
}
/// <summary>
/// Gets Moon Times, Altitude and Azimuth
/// </summary>
/// <param name="date">Date</param>
/// <param name="lat">Latitude</param>
/// <param name="lng">Longitude</param>
/// <param name="c">Celestial</param>
/// <param name="offset">Offset hours</param>
public static void GetMoonTimes(DateTime date, double lat, double lng, Celestial c, double offset)
{
//Get current Moon Position to populate passed Alt / Azi for user specified date
offset *= -1; //REVERSE OFFSET FOR POSITIONING
//Get current moon position and coordinate
MoonPosition mp = GetMoonPosition(date, lat, lng, c, offset, true);
double altRad = mp.Altitude / Math.PI * 180; //Convert alt to degrees
c.moonAltitude = (altRad - mp.ParallaxCorection); //Set altitude with adjusted parallax
c.moonAzimuth = mp.Azimuth / Math.PI * 180 + 180; //Azimuth in degrees + 180 for E by N.
////New Iterations for Moon set / rise
bool moonRise = false;
bool moonSet = false;
//Start at beginning of day
DateTime t = new DateTime(date.Year, date.Month, date.Day, 0, 0, 0, DateTimeKind.Utc);
//Get start of day Moon Pos
MoonPosition moonPos = GetMoonPosition(t, lat, lng, c, offset, false);
double alt1 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
DateTime?setTime = null;
DateTime?riseTime = null;
double hz = -.3 * rad;//Horizon degrees at -.3 for appearant rise / set
//Iterate for each hour of the day
for (int x = 1; x <= 24; x++)
{
moonPos = GetMoonPosition(t.AddHours(x), lat, lng, c, offset, false);//Get the next hours altitude for comparison
double alt2 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
//If hour 1 is below horizon and hour 2 is above
if (alt1 < hz && alt2 >= hz)
{
//Moon Rise Occurred
moonRise = true;
DateTime dt1 = t.AddHours(x - 1);
moonPos = GetMoonPosition(dt1, lat, lng, c, offset, false);//Get the next hours altitude for comparison
double altM1 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
//Iterate through each minute to determine at which minute the horizon is crossed.
//Interpolation is more efficient, but yielded results with deviations up to 5 minutes.
//Investigate formula efficiency
for (int y = 1; y <= 60; y++)
{
DateTime dt2 = t.AddHours(x - 1).AddMinutes(y);
moonPos = GetMoonPosition(dt2, lat, lng, c, offset, false);//Get the next hours altitude for comparison
double altM2 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
if (altM1 < hz && altM2 >= hz)
{
//interpolate seconds
double p = 60 * ((hz - altM1) / (altM2 - altM1));
riseTime = dt1.AddMinutes(y - 1).AddSeconds(p);
break;
}
altM1 = altM2;
}
}
//if hour 2 is above horizon and hour 1 below
if (alt1 >= hz && alt2 < hz)
{
//Moon Set Occurred
moonSet = true;
DateTime dt1 = t.AddHours(x - 1);
moonPos = GetMoonPosition(dt1, lat, lng, c, offset, false);//Get the next hours altitude for comparison
double altM1 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
//Iterate through each minute to determine at which minute the horizon is crossed.
//Interpolation is more efficient, but yielded results with deviations up to 5 minutes.
//Investigate formula efficiency
for (int y = 1; y <= 60; y++)
{
DateTime dt2 = t.AddHours(x - 1).AddMinutes(y);
moonPos = GetMoonPosition(dt2, lat, lng, c, offset, false);//Get the next hours altitude for comparison
double altM2 = moonPos.Altitude - (moonPos.ParallaxCorection * rad);
if (altM1 >= hz && altM2 < hz)
{
//Interpolate seconds
double p = 60 * ((hz - altM2) / (altM1 - altM2));
setTime = dt1.AddMinutes(y).AddSeconds(-p);
break;
}
altM1 = altM2;
}
}
alt1 = alt2;
if (moonRise && moonSet)
{
break;
}
}
c.moonSet = setTime;
c.moonRise = riseTime;
if (moonRise && moonSet)
{
c.moonCondition = CelestialStatus.RiseAndSet;
}
else
{
if (!moonRise && !moonSet)
{
if (alt1 >= 0)
{
c.moonCondition = CelestialStatus.UpAllDay;
}
else
{
c.moonCondition = CelestialStatus.DownAllDay;
}
}
if (!moonRise && moonSet)
{
c.moonCondition = CelestialStatus.NoRise;
}
if (moonRise && !moonSet)
{
c.moonCondition = CelestialStatus.NoSet;
}
}
}
