private ICollection <AstroEvent> FindLunarEclipses(AstroEventsContext context)
{
List <AstroEvent> events = new List <AstroEvent>();
int ln = LunarEphem.Lunation(context.From, LunationSystem.Meeus);
do
{
LunarEclipse eclipse = LunarEclipses.NearestEclipse(ln, next: true);
double jd = eclipse.JulianDayMaximum;
if (jd <= context.To)
{
double jdMax = jd;
string type = Text.Get($"LunarEclipse.Type.{eclipse.EclipseType}");
string phase = Formatters.Phase.Format(eclipse.Magnitude);
var elements = GetLunarEclipseElements(jdMax);
var local = LunarEclipses.LocalCircumstances(eclipse, elements, context.GeoLocation);
string localVisibility = GetLocalVisibilityString(eclipse, local);
events.Add(new AstroEvent(jdMax, Text.Get("LunarEclipse.Event", ("type", type), ("phase", phase), ("localVisibility", localVisibility)), moon));
ln = eclipse.MeeusLunationNumber + 1;
}
else
{
break;
}
}while (true);
return(events);
}
private ICollection <AstroEvent> FindSolarEclipses(AstroEventsContext context)
{
List <AstroEvent> events = new List <AstroEvent>();
int ln = LunarEphem.Lunation(context.From, LunationSystem.Meeus);
do
{
SolarEclipse eclipse = GetNearestSolarEclipse(ln, next: true, saros: false);
double jd = eclipse.JulianDayMaximum;
if (jd <= context.To)
{
var pbe = GetBesselianElements(jd);
var localCirc = SolarEclipses.LocalCircumstances(pbe, context.GeoLocation);
string type = Text.Get($"SolarEclipse.Type.{eclipse.EclipseType}");
string subtype = eclipse.IsNonCentral ? $" {Text.Get("SolarEclipse.Type.NoCentral")}" : "";
string phase = eclipse.EclipseType == SolarEclipseType.Partial ? $" ({Text.Get("SolarEclipse.MaxPhase")} {Formatters.Phase.Format(eclipse.Magnitude)})" : "";
double jdMax = localCirc.MaxMagnitude > 0 ? localCirc.Maximum.JulianDay : jd;
string localVisibility = GetLocalVisibilityString(eclipse, localCirc);
events.Add(new AstroEvent(jdMax, Text.Get("SolarEclipse.Event", ("type", type), ("subtype", subtype), ("phase", phase), ("localVisibility", localVisibility)), sun, moon));
ln = eclipse.MeeusLunationNumber + 1;
}
else
{
break;
}
}while (true);
return(events);
}
public void FindNearestLunarEclipse()
{
// ex. 54c
{
double jd = new Date(1973, 6, 1).ToJulianDay();
LunarEclipse eclipse = LunarEclipses.NearestEclipse(jd, true);
var d = new Date(eclipse.JulianDayMaximum, 0);
Assert.AreEqual(1973, d.Year);
Assert.AreEqual(6, d.Month);
Assert.AreEqual(15, (int)d.Day);
Assert.AreEqual(20, d.Hour);
Assert.AreEqual(50, d.Minute);
Assert.AreEqual(LunarEclipseType.Penumbral, eclipse.EclipseType);
Assert.AreEqual(0.462, eclipse.Magnitude, 1e-3);
}
// ex. 54d
{
double jd = new Date(1997, 7, 1).ToJulianDay();
int ln = LunarEphem.Lunation(jd, LunationSystem.Meeus);
LunarEclipse eclipse = LunarEclipses.NearestEclipse(ln, true);
var d = new Date(eclipse.JulianDayMaximum, 0);
Assert.AreEqual(1997, d.Year);
Assert.AreEqual(9, d.Month);
Assert.AreEqual(16, (int)d.Day);
Assert.AreEqual(18, d.Hour);
Assert.AreEqual(47, d.Minute);
Assert.AreEqual(LunarEclipseType.Total, eclipse.EclipseType);
Assert.AreEqual(1.187, eclipse.Magnitude, 1e-3);
}
}
public void LunationNumber()
{
Assert.AreEqual(1217, LunarEphem.Lunation(new Date(2021, 5, 11).ToJulianEphemerisDay()));
Assert.AreEqual(-282, LunarEphem.Lunation(new Date(1900, 2, 17).ToJulianEphemerisDay()));
}
/// <summary>
/// Calculates nearest solar eclipse (next or previous) for the provided lunation number.
/// </summary>
/// <param name="lunationNumber">Meeus lunation number of interest.</param>
/// <param name="next">Flag indicating searching direction. True means searching next eclipse, false means previous.</param>
/// <summary>
/// Calculates nearest lunar eclipse (next or previous) for the provided Julian Day.
/// </summary>
/// <param name="jd">Julian day of interest, the nearest lunar eclipse for that date will be found.</param>
/// <param name="next">Flag indicating searching direction. True means searching next eclipse, false means previous.</param>
public static LunarEclipse NearestEclipse(double jd, bool next)
{
int lunationNumber = LunarEphem.Lunation(jd, LunationSystem.Meeus);
return(NearestEclipse(lunationNumber, next));
}
/// <summary>
/// Gets Brown lunation number
/// </summary>
private int Lunation(SkyContext c)
{
double age = c.Get(Age);
return(LunarEphem.Lunation(c.JulianDay - age));
}