public void NearestPhase()
{
// 1 second error
double error = 1.0 / (24 * 60 * 60);
{
// New Moon takes place in February 1977
Date date = new Date(1977, 2, 15);
double jd = date.ToJulianEphemerisDay();
double jdNewMoon = LunarEphem.NearestPhase(jd, MoonPhase.NewMoon);
Assert.AreEqual(2443192.65118, jdNewMoon, error);
}
{
// First last quarter of 2044
Date date = new Date(2044, 1, 1);
double jd = date.ToJulianEphemerisDay();
double jdLastQuarter = LunarEphem.NearestPhase(jd, MoonPhase.LastQuarter);
Assert.AreEqual(2467636.49186, jdLastQuarter, error);
}
}
/// <summary>
/// Calculates instants of first sighting of lunar crescent on the evening sky, i.e. noumenia events.
/// </summary>
/// <remarks>
/// The method is based on work of B.D.Yallop,
/// see the work there: https://webspace.science.uu.nl/~gent0113/islam/downloads/naotn_69.pdf.
/// As it noted in the work (see page 12):
/// From observers reports it has been found that in general q = 0
/// is close to the lower limit for first visibility under
/// perfect atmospheric conditions at sea level without requiring optical aid.
/// Also lunar altitude should be checked: 2 degrees above horizon is an empyric value.
/// So, the condition of the event used there is "q > 0 && alt > 0"
/// </remarks>
private ICollection <AstroEvent> Noumenia(AstroEventsContext context)
{
List <AstroEvent> events = new List <AstroEvent>();
double jd = 0;
jd = context.From;
while (jd < context.To)
{
if (context.CancelToken?.IsCancellationRequested == true)
{
return(new AstroEvent[0]);
}
else
{
double jdNewMoon = LunarEphem.NearestPhase(jd, MoonPhase.NewMoon);
for (int day = 0; day <= 7; day++)
{
var ctx = new SkyContext(jdNewMoon + day, context.GeoLocation, preferFast: true);
double jdMidnight = ctx.JulianDayMidnight;
var rtsSun = ctx.Get(solarCalc.RiseTransitSet);
var rtsMoon = ctx.Get(lunarCalc.RiseTransitSet);
var sunSet = double.IsNaN(rtsSun.Set) ? 1 : rtsSun.Set;
var moonSet = double.IsNaN(rtsMoon.Set) ? 1 : rtsMoon.Set;
double jdBestTime = jdMidnight + sunSet + 4.0 / 9.0 * (moonSet - sunSet);
ctx = new SkyContext(jdBestTime, context.GeoLocation, preferFast: true);
double alt = ctx.Get(lunarCalc.Horizontal).Altitude;
double q = ctx.Get(lunarCalc.CrescentQ);
if (q > 0 && alt > 2)
{
events.Add(new AstroEvent(jdBestTime, Text.Get("MoonEvents.Noumenia.Text"), lunarCalc.Moon));
break;
}
}
jd = jdNewMoon + LunarEphem.SINODIC_PERIOD;
}
}
return(events);
}
/// <summary>
/// Calculates dates of lunar phases within specified range
/// </summary>
private ICollection <AstroEvent> Phases(AstroEventsContext context)
{
List <AstroEvent> events = new List <AstroEvent>();
double jd = 0;
jd = context.From;
while (jd < context.To)
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.NewMoon);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.NewMoon"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
jd = context.From;
while (jd < context.To)
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.FirstQuarter);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.FirstQuarter"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
jd = context.From;
while (jd < context.To)
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.FullMoon);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.FullMoon"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
jd = context.From;
while (jd < context.To)
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.LastQuarter);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.LastQuarter"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
return(events);
}
/// <summary>
/// Calculates dates of lunar phases within specified range
/// </summary>
private ICollection <AstroEvent> Phases(AstroEventsContext context)
{
List <AstroEvent> events = new List <AstroEvent>();
double jd = 0;
jd = context.From;
while (jd < context.To)
{
if (context.CancelToken?.IsCancellationRequested == true)
{
return(new AstroEvent[0]);
}
else
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.NewMoon);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.NewMoon"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
}
jd = context.From;
while (jd < context.To)
{
if (context.CancelToken?.IsCancellationRequested == true)
{
return(new AstroEvent[0]);
}
else
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.FirstQuarter);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.FirstQuarter"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
}
jd = context.From;
while (jd < context.To)
{
if (context.CancelToken?.IsCancellationRequested == true)
{
return(new AstroEvent[0]);
}
else
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.FullMoon);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.FullMoon"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
}
jd = context.From;
while (jd < context.To)
{
if (context.CancelToken?.IsCancellationRequested == true)
{
return(new AstroEvent[0]);
}
else
{
jd = LunarEphem.NearestPhase(jd, MoonPhase.LastQuarter);
events.Add(new AstroEvent(jd, Text.Get("MoonEvents.Phases.LastQuarter"), lunarCalc.Moon));
jd += LunarEphem.SINODIC_PERIOD;
}
}
return(events);
}
/// <summary>
/// Gets nearest phase date
/// </summary>
private Date NearestPhase(SkyContext c, MoonPhase p)
{
return(c.GetDate(LunarEphem.NearestPhase(c.JulianDay, p)));
}