public static SolarClock SolarClock(this DateTime dt, double latitude, double longitude,
double gmtoffset, bool atmRefrac)
{
SolarClock sc = new SolarClock();
sc.gregoriandate = dt;
//this is where we calcuclated the julian day, day index of the year
double n1 = Math.Floor((double)dt.Month * 275 / 9);
double n2 = Math.Floor((double)(dt.Month + 9) / 12);
double n3 = 1 + (Math.Floor((dt.Year - 4 * Math.Floor((double)dt.Year / 4) + 2) / 3));
sc.julian = (int)(n1 - (n2 * n3) + dt.Day - 30);
double B = ((double)(sc.julian - 81) * 360 / 365);
sc.declination = Algebric.SineInv(Algebric.Sine(23.45) * Algebric.Sine(B));
var lstm = 15 * gmtoffset; //local standard time meridian
var eot = 9.87 * (Algebric.Sine(2 * B)) - 7.53 * Algebric.Cosine(B) - 1.5 * Algebric.Sine(B); //equation of time
var tc = (4 * (longitude - lstm)) + eot; //total time correction in minutes
sc.noon = dt.AddHours(12 - (tc / 60));
var noonHourAngle = (tc / 60) * 15; //this is the time corection in degrees
//this is to consider the atmospheric refraction , but not all methods would consider atm refraction
//so this param is kept as conditional one
var refrac = atmRefrac == true?Algebric.Sine(-0.83) : 0;
var lngdecleffect = (refrac - (Algebric.Sine(sc.declination) * Algebric.Sine(latitude))) /
(Algebric.Cosine(sc.declination) * Algebric.Cosine(latitude));
var sunrise = 12 - (Algebric.CosineInv(lngdecleffect) / 15) - (tc / 60);
sc.sunrise = dt.AddHours(sunrise);
TimeSpan halfday = sc.noon.Subtract(sc.sunrise);
sc.sunset = sc.noon.AddHours(halfday.Hours).AddMinutes(halfday.Minutes).AddSeconds(halfday.Seconds);
sc.daylength = sc.sunset.Subtract(sc.sunrise);
return(sc);
}
//these are deprecated methods since the formula is foudn to be not correct
public static DateTime Rise(double latitude, double longitude, DateTime dt, double zenith, double localOffset)
{
//this would get the julian day for us
double n1 = Math.Floor((double)dt.Month * 275 / 9);
double n2 = Math.Floor((double)(dt.Month + 9) / 12);
double n3 = 1 + (Math.Floor((dt.Year - 4 * Math.Floor((double)dt.Year / 4) + 2) / 3));
var N = n1 - (n2 * n3) + dt.Day - 30;
//once the julian day is calculated then the longitudinal correction for the julian day is made
var lngHour = longitude / 15;
var t = N + ((6 - lngHour) / 24);
var M = (0.9856 * t) - 3.289; //suns mean anomaly
var L = M + (1.916 * Algebric.Sine(M)) + (0.020 * Algebric.Sine(2 * M)) + 282.634; //this is the tru solar longitude
L = L < 0 ? L + 360 : L > 360 ? L - 360 : L; //adjusting the value of solar longitude to [0, 360) domain
//this is where we calculate the solar right ascension
var RA = Algebric.TangentInv(0.91764 * Algebric.Tangent(L));
var Lquadrant = (Math.Floor(L / 90)) * 90;
var RAquadrant = (Math.Floor(RA / 90)) * 90;
RA = RA + (Lquadrant - RAquadrant);
RA = RA / 15;//right ascensionin hours from longitude
//this is where we calcualate the declination
var sinDec = 0.39782 * Algebric.Sine(L);
var cosDec = Algebric.Cosine(Algebric.SineInv(sinDec));
var cosH = (Algebric.Cosine(zenith) - (sinDec * Algebric.Sine(latitude))) / (cosDec * Algebric.Cosine(latitude));
var H = 360 - Algebric.CosineInv(cosH);//this is the suns local hour angle
H = H / 15;
var T = H + RA - (0.06571 * t) - 6.622; //this is the local mean time of rising and setting
var UT = T - lngHour; //getting the UTC mean time for rising
UT = UT < 0 ? UT + 24 : UT > 24 ? UT - 24 : UT; //this is adjustment for [0., 24)
var localT = UT + localOffset; //local time for rise
return(new DateTime(dt.Year, dt.Month, dt.Day,
dt.AddHours(localT).Hour, dt.AddHours(localT).Minute, dt.AddHours(localT).Second));
}