private float NeptuneMoon_Magnitude(SkyContext c, int m)
{
var delta = c.Get(Planet_DistanceFromEarth, Planet.NEPTUNE);
double r = c.Get(Planet_DistanceFromSun, Planet.NEPTUNE);
return(NeptunianMoons.Magnitude(delta, r, m));
}
private CrdsEcliptical NeptuneMoon_Ecliptical(SkyContext c, int m)
{
var eclNeptune = c.Get(Planet_Ecliptical, Planet.NEPTUNE);
return(NeptunianMoons.Position(c.JulianDay, eclNeptune, m));
}
private double NeptuneMoon_Semidiameter(SkyContext c, int m)
{
var ecl = c.Get(NeptuneMoon_Ecliptical, m);
return(NeptunianMoons.Semidiameter(ecl.Distance, m));
}
public void Positions()
{
// Test data is obtained from NASA JPL Ephemeris tool
// https://ssd.jpl.nasa.gov/horizons.cgi
List <TestData> testDatas = new List <TestData>()
{
// Triton
// 2020-Jan-07 13:00 2458856.041666667 -0.964 12.797
new TestData()
{
MoonNumber = 1,
Neptune = new CrdsEcliptical(new DMS("346* 24' 16.12''"), new DMS("-1* 01' 26.26''"), 30.416),
JulianDay = 2458856.041666667,
X = -0.964,
Y = 12.797
},
// Triton
// 2025-Jan-22 19:00 2460698.291666667 1.086 -12.382
new TestData()
{
MoonNumber = 1,
Neptune = new CrdsEcliptical(new DMS("357° 43' 31.73''"), new DMS("-1° 16' 24.69''"), 30.416),
JulianDay = 2460698.291666667,
X = 1.086,
Y = -12.382
},
// Nereid
// 2020-Feb-27 00:00 2458906.500000000 5.124 10.556
new TestData()
{
MoonNumber = 2,
Neptune = new CrdsEcliptical(new DMS("348* 00' 11.97''"), new DMS("-1* 00' 54.27''"), 30.906),
JulianDay = 2458906.5,
X = 5.124,
Y = 10.556
},
// Nereid
// 2020-Jul-13 00:00 2459043.500000000 384.491 206.269
new TestData()
{
MoonNumber = 2,
Neptune = new CrdsEcliptical(new DMS("350* 51' 10.8''"), new DMS("-1* 05' 15.56''"), 29.405),
JulianDay = 2459043.5,
X = 384.491,
Y = 206.269
},
// Nereid
// 1980-Jan-01 00:00 2444239.500000000 135.407 32.771
new TestData()
{
MoonNumber = 2,
Neptune = new CrdsEcliptical(new DMS("260* 55' 41.93''"), new DMS("+1* 20' 26.28''"), 31.209),
JulianDay = 2444239.5,
X = 135.407,
Y = 32.771
}
};
// possible error in coordinates is 1 arcsecond
const double error = 1;
foreach (var testData in testDatas)
{
NutationElements ne = Nutation.NutationElements(testData.JulianDay);
double epsilon = Date.TrueObliquity(testData.JulianDay, ne.deltaEpsilon);
CrdsEcliptical eclSatellite = NeptunianMoons.Position(testData.JulianDay, testData.Neptune, testData.MoonNumber);
CrdsEquatorial eqNeptune = testData.Neptune.ToEquatorial(epsilon);
CrdsEquatorial eqSatellite = eclSatellite.ToEquatorial(epsilon);
double X = (eqSatellite.Alpha - eqNeptune.Alpha) * Math.Cos(Angle.ToRadians(eqNeptune.Delta)) * 3600;
double Y = (eqSatellite.Delta - eqNeptune.Delta) * 3600;
Assert.AreEqual(testData.X, X, error);
Assert.AreEqual(testData.Y, Y, error);
}
}
