Merge pull request #32 from jfcarr-astronomy/moon/dist-ad-hp

Calculate -> Moon's distance, angular diameter, and horizontal parallax

PALib.Tests/PAMoon.cs

@@ -34,5 +34,11 @@ public void TimesOfNewMoonAndFullMoon()
 		{
 			Assert.Equal((17, 27, 27, 8, 2003, 16, 36, 10, 9, 2003), _paMoon.TimesOfNewMoonAndFullMoon(false, 0, 1, 9, 2003));
 		}
+
+		[Fact]
+		public void MoonDistAngDiamHorParallax()
+		{
+			Assert.Equal((367964, 0, 32, 0, 59, 35.49), _paMoon.MoonDistAngDiamHorParallax(0, 0, 0, false, 0, 1, 9, 2003));
+		}
 	}
 }

PALib/PAMacros.cs

@@ -1762,6 +1762,53 @@ public static double MoonHP(double lh, double lm, double ls, int ds, int zc, dou
 			return pm;
 		}
 
+		/// <summary>
+		/// Calculate distance from the Earth to the Moon (km)
+		/// </summary>
+		/// <remarks>
+		/// Original macro name: MoonDist
+		/// </remarks>
+		/// <param name="lh"></param>
+		/// <param name="lm"></param>
+		/// <param name="ls"></param>
+		/// <param name="ds"></param>
+		/// <param name="zc"></param>
+		/// <param name="dy"></param>
+		/// <param name="mn"></param>
+		/// <param name="yr"></param>
+		/// <returns></returns>
+		public static double MoonDist(double lh, double lm, double ls, int ds, int zc, double dy, int mn, int yr)
+		{
+			var hp = (MoonHP(lh, lm, ls, ds, zc, dy, mn, yr)).ToRadians();
+			var r = 6378.14 / hp.Sine();
+
+			return r;
+		}
+
+		/// <summary>
+		/// Calculate the Moon's angular diameter (degrees)
+		/// </summary>
+		/// <remarks>
+		/// Original macro name: MoonSize
+		/// </remarks>
+		/// <param name="lh"></param>
+		/// <param name="lm"></param>
+		/// <param name="ls"></param>
+		/// <param name="ds"></param>
+		/// <param name="zc"></param>
+		/// <param name="dy"></param>
+		/// <param name="mn"></param>
+		/// <param name="yr"></param>
+		/// <returns></returns>
+		public static double MoonSize(double lh, double lm, double ls, int ds, int zc, double dy, int mn, int yr)
+		{
+			var hp = (MoonHP(lh, lm, ls, ds, zc, dy, mn, yr)).ToRadians();
+			var r = 6378.14 / hp.Sine();
+			var th = 384401.0 * 0.5181 / r;
+
+			return th;
+		}
+
 		/// <summary>
 		/// Convert angle in radians to equivalent angle in degrees.
 		/// </summary>

PALib/PAMoon.cs

@@ -236,5 +236,42 @@ public class PAMoon
 
 			return (nmLocalTimeHour, nmLocalTimeMin, nmLocalDateDay, nmLocalDateMonth, nmLocalDateYear, fmLocalTimeHour, fmLocalTimeMin, fmLocalDateDay, fmLocalDateMonth, fmLocalDateYear);
 		}
+
+		/// <summary>
+		/// Calculate Moon's distance, angular diameter, and horizontal parallax.
+		/// </summary>
+		/// <param name="lctHour"></param>
+		/// <param name="lctMin"></param>
+		/// <param name="lctSec"></param>
+		/// <param name="isDaylightSaving"></param>
+		/// <param name="zoneCorrectionHours"></param>
+		/// <param name="localDateDay"></param>
+		/// <param name="localDateMonth"></param>
+		/// <param name="localDateYear"></param>
+		/// <returns>
+		/// <para>earth_moon_dist -- Earth-Moon distance (km)</para>
+		/// <para>ang_diameter_deg -- Angular diameter (degrees part)</para>
+		/// <para>ang_diameter_min -- Angular diameter (minutes part)</para>
+		/// <para>hor_parallax_deg -- Horizontal parallax (degrees part)</para>
+		/// <para>hor_parallax_min -- Horizontal parallax (minutes part)</para>
+		/// <para>hor_parallax_sec -- Horizontal parallax (seconds part)</para>
+		/// </returns>
+		public (double earthMoonDist, double angDiameterDeg, double angDiameterMin, double horParallaxDeg, double horParallaxMin, double horParallaxSec) MoonDistAngDiamHorParallax(double lctHour, double lctMin, double lctSec, bool isDaylightSaving, int zoneCorrectionHours, double localDateDay, int localDateMonth, int localDateYear)
+		{
+			var daylightSaving = (isDaylightSaving) ? 1 : 0;
+
+			var moonDistance = PAMacros.MoonDist(lctHour, lctMin, lctSec, daylightSaving, zoneCorrectionHours, localDateDay, localDateMonth, localDateYear);
+			var moonAngularDiameter = PAMacros.MoonSize(lctHour, lctMin, lctSec, daylightSaving, zoneCorrectionHours, localDateDay, localDateMonth, localDateYear);
+			var moonHorizontalParallax = PAMacros.MoonHP(lctHour, lctMin, lctSec, daylightSaving, zoneCorrectionHours, localDateDay, localDateMonth, localDateYear);
+
+			var earthMoonDist = Math.Round(moonDistance, 0);
+			var angDiameterDeg = PAMacros.DecimalDegreesDegrees(moonAngularDiameter + 0.008333);
+			var angDiameterMin = PAMacros.DecimalDegreesMinutes(moonAngularDiameter + 0.008333);
+			var horParallaxDeg = PAMacros.DecimalDegreesDegrees(moonHorizontalParallax);
+			var horParallaxMin = PAMacros.DecimalDegreesMinutes(moonHorizontalParallax);
+			var horParallaxSec = PAMacros.DecimalDegreesSeconds(moonHorizontalParallax);
+
+			return (earthMoonDist, angDiameterDeg, angDiameterMin, horParallaxDeg, horParallaxMin, horParallaxSec);
+		}
 	}
 }

README.md

@@ -59,7 +59,7 @@ If you're interested in this topic, please buy the book! It provides far more de
 - [x] Calculate -> Approximate and precise position of Moon
 - [x] Calculate -> Moon phase and position angle of bright limb
 - [x] Calculate -> Times of new Moon and full Moon
-- [ ] Calculate -> Moon's distance, angular diameter, and horizontal parallax
+- [x] Calculate -> Moon's distance, angular diameter, and horizontal parallax
 - [ ] Calculate -> Local moonrise and moonset
 
 ### Eclipses