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Astronomy: Add sunrise / sunset calculation.

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srcejon 2024-03-27 16:46:27 +00:00
parent 4c35cb90ad
commit 0ab0f33d00
2 changed files with 52 additions and 0 deletions
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49
sdrbase/util/astronomy.cpp
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@ -76,6 +76,12 @@ double Astronomy::modifiedJulianDate(QDateTime dt)
return Astronomy::julianDate(dt) - 2400000.5;
}
// Convert Julian date to QDateTime
QDateTime Astronomy::julianDateToDateTime(double jd)
{
return QDateTime::fromSecsSinceEpoch((jd - 2440587.5) * 24.0*60.0*60.0);
}
// Get Julian date of J2000 Epoch
double Astronomy::jd_j2000(void)
{
@ -903,6 +909,49 @@ double Astronomy::observerVelocityLSRK(RADec rd, double latitude, double longitu
return vRot + vOrbit + vSun;
}
// Calculate sunrise and sunset time
// From: https://en.wikipedia.org/wiki/Sunrise_equation
// Probably accurate to within a couple of minutes
void Astronomy::sunrise(QDate date, double latitude, double longitude, QDateTime& rise, QDateTime& set)
{
// Calculate Julian day
double n = std::ceil(Astronomy::julianDate(QDateTime(date, QTime(0, 0, 0))) - 2451545.0 + (69.184 / 86400.0));
// Mean solar time
double jStar = n - longitude / 360.0;
// Solar mean anomaly
double m = Astronomy::modulo(357.5291 + 0.98560028 * jStar, 360.0);
double mRad = Units::degreesToRadians(m);
// Equation of the center
double c = 1.9148 * sin(mRad) + 0.02 * sin(2.0 * mRad) + 0.0003 * sin(3 * mRad);
// Ecliptic longitude
double lambda = Astronomy::modulo(m + c + 180.0 + 102.9372, 360.0);
double lambdaRad = Units::degreesToRadians(lambda);
// Solar transit
double jTransit = 2451545.0 + jStar + 0.0053 * sin(mRad) - 0.0069 * sin(2.0 * lambdaRad);
// Declination of the Sun
const double tilt = 23.4397;
const double tiltRad = Units::degreesToRadians(tilt);
double sunDecRad = asin(sin(lambdaRad) * sin(tiltRad));
// Hour angle
double latitudeRad = Units::degreesToRadians(latitude);
double omega0Rad = acos((sin(Units::degreesToRadians(-0.833)) - sin(latitudeRad) * sin(sunDecRad)) / (cos(latitudeRad) * cos(sunDecRad)));
double omega0 = Units::radiansToDegrees(omega0Rad);
// Rise and set times
double jRise = jTransit - omega0 / 360.0;
double jSet = jTransit + omega0 / 360.0;
rise = Astronomy::julianDateToDateTime(jRise);
set = Astronomy::julianDateToDateTime(jSet);
}
// Calculate thermal noise power for a given temperature in Kelvin and bandwidth in Hz
double Astronomy::noisePowerdBm(double temp, double bw)
{

3
sdrbase/util/astronomy.h
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@ -40,6 +40,7 @@ public:
static double julianDate(int year, int month, int day, int hours, int minutes, int seconds);
static double julianDate(QDateTime dt);
static double modifiedJulianDate(QDateTime dt);
static QDateTime julianDateToDateTime(double jd);
static double jd_j2000(void);
static double jd_b1950(void);
@ -80,6 +81,8 @@ public:
static double sunVelocityLSRK(RADec rd);
static double observerVelocityLSRK(RADec rd, double latitude, double longitude, QDateTime dt);
static void sunrise(QDate date, double latitude, double longitude, QDateTime& rise, QDateTime& set);
static double noisePowerdBm(double temp, double bw);
static double noiseTemp(double dBm, double bw);