kopia lustrzana https://github.com/dl2alf/AirScout
227 wiersze
7.2 KiB
C#
227 wiersze
7.2 KiB
C#
// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="Sun.cs" company="OxyPlot">
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// Copyright (c) 2014 OxyPlot contributors
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// </copyright>
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// <summary>
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// Calculation of sunrise/sunset
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// </summary>
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// --------------------------------------------------------------------------------------------------------------------
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namespace ExampleLibrary
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{
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using System;
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/// <summary>
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/// Calculation of sunrise/sunset
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/// </summary>
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/// <remarks>http://williams.best.vwh.net/sunrise_sunset_algorithm.htm
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/// based on code by Huysentruit Wouter, Fastload-Media.be</remarks>
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public static class Sun
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{
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private static double Deg2Rad(double angle)
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{
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return Math.PI * angle / 180.0;
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}
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private static double Rad2Deg(double angle)
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{
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return 180.0 * angle / Math.PI;
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}
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private static double FixValue(double value, double min, double max)
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{
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while (value < min)
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{
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value += max - min;
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}
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while (value >= max)
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{
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value -= max - min;
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}
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return value;
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}
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public static DateTime Calculate(DateTime date, double latitude, double longitude, bool sunrise, Func<DateTime, DateTime> utcToLocalTime, double zenith = 90.5)
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{
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// 1. first calculate the day of the year
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int n = date.DayOfYear;
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// 2. convert the longitude to hour value and calculate an approximate time
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double lngHour = longitude / 15.0;
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double t;
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if (sunrise)
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{
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t = n + ((6.0 - lngHour) / 24.0);
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}
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else
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{
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t = n + ((18.0 - lngHour) / 24.0);
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}
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// 3. calculate the Sun's mean anomaly
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double m = (0.9856 * t) - 3.289;
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// 4. calculate the Sun's true longitude
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double l = m + (1.916 * Math.Sin(Deg2Rad(m))) + (0.020 * Math.Sin(Deg2Rad(2 * m))) + 282.634;
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l = FixValue(l, 0, 360);
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// 5a. calculate the Sun's right ascension
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double ra = Rad2Deg(Math.Atan(0.91764 * Math.Tan(Deg2Rad(l))));
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ra = FixValue(ra, 0, 360);
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// 5b. right ascension value needs to be in the same quadrant as L
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double lquadrant = Math.Floor(l / 90.0) * 90.0;
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double raquadrant = Math.Floor(ra / 90.0) * 90.0;
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ra = ra + (lquadrant - raquadrant);
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// 5c. right ascension value needs to be converted into hours
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ra = ra / 15.0;
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// 6. calculate the Sun's declination
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double sinDec = 0.39782 * Math.Sin(Deg2Rad(l));
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double cosDec = Math.Cos(Math.Asin(sinDec));
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// 7a. calculate the Sun's local hour angle
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double cosH = (Math.Cos(Deg2Rad(zenith)) - (sinDec * Math.Sin(Deg2Rad(latitude)))) /
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(cosDec * Math.Cos(Deg2Rad(latitude)));
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// 7b. finish calculating H and convert into hours
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double h;
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if (sunrise)
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{
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h = 360.0 - Rad2Deg(Math.Acos(cosH));
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}
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else
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{
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h = Rad2Deg(Math.Acos(cosH));
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}
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h = h / 15.0;
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// 8. calculate local mean time of rising/setting
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double localMeanTime = h + ra - (0.06571 * t) - 6.622;
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// 9. adjust back to UTC
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double utc = localMeanTime - lngHour;
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// 10. convert UT value to local time zone of latitude/longitude
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date = new DateTime(date.Year, date.Month, date.Day, 0, 0, 0, DateTimeKind.Utc);
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var utctime = date.AddHours(utc);
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var localTime = utcToLocalTime(utctime);
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utc = (localTime - date).TotalHours;
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utc = FixValue(utc, 0, 24);
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return date.AddHours(utc);
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}
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}
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/*
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Sunrise/Sunset Algorithm
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Source:
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Almanac for Computers, 1990
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published by Nautical Almanac Office
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United States Naval Observatory
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Washington, DC 20392
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Inputs:
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day, month, year: date of sunrise/sunset
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latitude, longitude: location for sunrise/sunset
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zenith: Sun's zenith for sunrise/sunset
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offical = 90 degrees 50'
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civil = 96 degrees
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nautical = 102 degrees
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astronomical = 108 degrees
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NOTE: longitude is positive for East and negative for West
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NOTE: the algorithm assumes the use of a calculator with the
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trig functions in "degree" (rather than "radian") mode. Most
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programming languages assume radian arguments, requiring back
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and forth convertions. The factor is 180/pi. So, for instance,
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the equation RA = atan(0.91764 * tan(L)) would be coded as RA
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= (180/pi)*atan(0.91764 * tan((pi/180)*L)) to give a degree
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answer with a degree input for L.
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1. first calculate the day of the year
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N1 = floor(275 * month / 9)
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N2 = floor((month + 9) / 12)
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N3 = (1 + floor((year - 4 * floor(year / 4) + 2) / 3))
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N = N1 - (N2 * N3) + day - 30
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2. convert the longitude to hour value and calculate an approximate time
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lngHour = longitude / 15
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if rising time is desired:
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t = N + ((6 - lngHour) / 24)
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if setting time is desired:
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t = N + ((18 - lngHour) / 24)
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3. calculate the Sun's mean anomaly
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M = (0.9856 * t) - 3.289
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4. calculate the Sun's true longitude
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L = M + (1.916 * sin(M)) + (0.020 * sin(2 * M)) + 282.634
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NOTE: L potentially needs to be adjusted into the range [0,360) by adding/subtracting 360
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5a. calculate the Sun's right ascension
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RA = atan(0.91764 * tan(L))
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NOTE: RA potentially needs to be adjusted into the range [0,360) by adding/subtracting 360
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5b. right ascension value needs to be in the same quadrant as L
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Lquadrant = (floor( L/90)) * 90
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RAquadrant = (floor(RA/90)) * 90
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RA = RA + (Lquadrant - RAquadrant)
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5c. right ascension value needs to be converted into hours
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RA = RA / 15
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6. calculate the Sun's declination
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sinDec = 0.39782 * sin(L)
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cosDec = cos(asin(sinDec))
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7a. calculate the Sun's local hour angle
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cosH = (cos(zenith) - (sinDec * sin(latitude))) / (cosDec * cos(latitude))
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if (cosH > 1)
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the sun never rises on this location (on the specified date)
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if (cosH < -1)
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the sun never sets on this location (on the specified date)
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7b. finish calculating H and convert into hours
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if if rising time is desired:
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H = 360 - acos(cosH)
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if setting time is desired:
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H = acos(cosH)
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H = H / 15
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8. calculate local mean time of rising/setting
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T = H + RA - (0.06571 * t) - 6.622
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9. adjust back to UTC
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UT = T - lngHour
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NOTE: UT potentially needs to be adjusted into the range [0,24) by adding/subtracting 24
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10. convert UT value to local time zone of latitude/longitude
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localT = UT + localOffset
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*/
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} |