Merge pull request #47 from observerly/feature/dusk/ConvertEclipticCo…

…ordinateToEquatorial

feat: Added ConvertEclipticCoordinateToEquatorial().

coverage.txt

@@ -1,34 +1,13 @@
 mode: atomic
-github.com/observerly/dusk/pkg/dusk/solar.go:21.45,24.2 1 31
-github.com/observerly/dusk/pkg/dusk/solar.go:33.50,36.2 1 28
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-github.com/observerly/dusk/pkg/dusk/solar.go:81.47,86.11 2 8
-github.com/observerly/dusk/pkg/dusk/solar.go:90.2,90.10 1 8
-github.com/observerly/dusk/pkg/dusk/solar.go:86.11,88.3 1 8
-github.com/observerly/dusk/pkg/dusk/solar.go:106.110,112.2 2 24
-github.com/observerly/dusk/pkg/dusk/solar.go:123.142,151.2 12 23
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:10.30,12.2 1 446
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:14.30,16.2 1 90
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:18.44,20.2 1 121
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:22.30,24.2 1 5
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:26.31,28.2 1 30
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:30.31,32.2 1 26
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:34.31,36.2 1 1
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:38.36,40.2 1 5
-github.com/observerly/dusk/pkg/dusk/twilight.go:38.163,49.16 5 9
-github.com/observerly/dusk/pkg/dusk/twilight.go:53.2,57.18 1 9
-github.com/observerly/dusk/pkg/dusk/twilight.go:49.16,51.3 1 0
-github.com/observerly/dusk/pkg/dusk/twilight.go:69.139,74.2 2 3
-github.com/observerly/dusk/pkg/dusk/twilight.go:85.142,90.2 2 3
-github.com/observerly/dusk/pkg/dusk/twilight.go:101.146,106.2 2 3
 github.com/observerly/dusk/pkg/dusk/utils.go:15.34,17.2 1 5
-github.com/observerly/dusk/pkg/dusk/utils.go:26.55,31.12 2 4
-github.com/observerly/dusk/pkg/dusk/utils.go:35.2,35.11 1 4
+github.com/observerly/dusk/pkg/dusk/utils.go:26.55,31.12 2 6
+github.com/observerly/dusk/pkg/dusk/utils.go:35.2,35.11 1 6
 github.com/observerly/dusk/pkg/dusk/utils.go:31.12,33.3 1 0
 github.com/observerly/dusk/pkg/dusk/utils.go:47.84,49.2 1 4
-github.com/observerly/dusk/pkg/dusk/utils.go:60.84,62.2 1 4
+github.com/observerly/dusk/pkg/dusk/utils.go:60.84,62.2 1 6
+github.com/observerly/dusk/pkg/dusk/coordinates.go:26.108,45.12 10 2
+github.com/observerly/dusk/pkg/dusk/coordinates.go:49.2,52.3 1 2
+github.com/observerly/dusk/pkg/dusk/coordinates.go:45.12,47.3 1 2
 github.com/observerly/dusk/pkg/dusk/epoch.go:31.48,36.2 2 62
 github.com/observerly/dusk/pkg/dusk/epoch.go:43.45,45.2 1 70
 github.com/observerly/dusk/pkg/dusk/epoch.go:53.65,64.2 4 31
@@ -44,39 +23,52 @@ github.com/observerly/dusk/pkg/dusk/epoch.go:170.70,175.2 2 30
 github.com/observerly/dusk/pkg/dusk/lunar.go:15.47,20.11 2 15
 github.com/observerly/dusk/pkg/dusk/lunar.go:24.2,24.10 1 15
 github.com/observerly/dusk/pkg/dusk/lunar.go:20.11,22.3 1 12
-github.com/observerly/dusk/pkg/dusk/lunar.go:34.48,39.11 2 3
-github.com/observerly/dusk/pkg/dusk/lunar.go:43.2,43.10 1 3
-github.com/observerly/dusk/pkg/dusk/lunar.go:39.11,41.3 1 3
-github.com/observerly/dusk/pkg/dusk/lunar.go:53.45,58.11 2 8
-github.com/observerly/dusk/pkg/dusk/lunar.go:62.2,62.10 1 8
-github.com/observerly/dusk/pkg/dusk/lunar.go:58.11,60.3 1 5
-github.com/observerly/dusk/pkg/dusk/lunar.go:72.52,77.11 2 8
-github.com/observerly/dusk/pkg/dusk/lunar.go:81.2,81.10 1 8
-github.com/observerly/dusk/pkg/dusk/lunar.go:77.11,79.3 1 5
+github.com/observerly/dusk/pkg/dusk/lunar.go:34.48,39.11 2 1
+github.com/observerly/dusk/pkg/dusk/lunar.go:43.2,43.10 1 1
+github.com/observerly/dusk/pkg/dusk/lunar.go:39.11,41.3 1 1
+github.com/observerly/dusk/pkg/dusk/lunar.go:53.45,58.11 2 6
+github.com/observerly/dusk/pkg/dusk/lunar.go:62.2,62.10 1 6
+github.com/observerly/dusk/pkg/dusk/lunar.go:58.11,60.3 1 3
+github.com/observerly/dusk/pkg/dusk/lunar.go:72.52,77.11 2 6
+github.com/observerly/dusk/pkg/dusk/lunar.go:81.2,81.10 1 6
+github.com/observerly/dusk/pkg/dusk/lunar.go:77.11,79.3 1 3
 github.com/observerly/dusk/pkg/dusk/lunar.go:91.64,96.11 2 5
 github.com/observerly/dusk/pkg/dusk/lunar.go:100.2,100.10 1 5
 github.com/observerly/dusk/pkg/dusk/lunar.go:96.11,98.3 1 0
 github.com/observerly/dusk/pkg/dusk/lunar.go:109.52,114.11 2 5
 github.com/observerly/dusk/pkg/dusk/lunar.go:118.2,118.10 1 5
 github.com/observerly/dusk/pkg/dusk/lunar.go:114.11,116.3 1 2
-github.com/observerly/dusk/pkg/dusk/lunar.go:128.61,133.12 2 8
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 github.com/observerly/dusk/pkg/dusk/lunar.go:172.74,197.2 10 4
-github.com/observerly/dusk/pkg/dusk/lunar.go:207.70,236.20 15 2
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-github.com/observerly/dusk/pkg/dusk/lunar.go:269.2,273.3 1 2
-github.com/observerly/dusk/pkg/dusk/lunar.go:236.20,241.14 3 120
-github.com/observerly/dusk/pkg/dusk/lunar.go:242.10,244.21 2 64
-github.com/observerly/dusk/pkg/dusk/lunar.go:245.14,247.25 2 44
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-github.com/observerly/dusk/pkg/dusk/lunar.go:260.10,261.21 1 68
-github.com/observerly/dusk/pkg/dusk/lunar.go:262.14,263.25 1 48
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+github.com/observerly/dusk/pkg/dusk/solar.go:21.45,24.2 1 29
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pkg/dusk/coordinates.go

@@ -1,5 +1,9 @@
 package dusk
 
+import (
+	"time"
+)
+
 type EquatorialCoordinate struct {
 	ra  float64
 	dec float64
@@ -10,3 +14,40 @@ type EclipticCoordinate struct {
 	β float64
 	Δ float64
 }
+
+/*
+	ConvertEclipticCoordinateToEquatorial()
+
+	@param datetime - the datetime of the observer (in UTC)
+	@param geocentric ecliptic coordinate of type EclipticCoordinate { λ, β, Λ }
+	@returns the converted equatorial coordinate { ra, dec }
+	@see eq13.3 & eq13.4 p.93 of Meeus, Jean. 1991. Astronomical algorithms. Richmond, Va: Willmann-Bell.
+*/
+func ConvertEclipticCoordinateToEquatorial(datetime time.Time, ec EclipticCoordinate) EquatorialCoordinate {
+	var J = GetCurrentJulianCenturyRelativeToJ2000(datetime)
+
+	var L float64 = GetSolarMeanLongitude(J)
+
+	var l float64 = GetLunarMeanLongitude(J)
+
+	var Ω float64 = GetLunarLongitudeOfTheAscendingNode(J)
+
+	var ε float64 = GetMeanObliquityOfTheEcliptic(J) + GetNutationInObliquityOfTheEcliptic(L, l, Ω)
+
+	var λ = ec.λ
+
+	var β = ec.β
+
+	var α = atanx((sinx(λ)*cosx(ε) - tanx(β)*sinx(ε)) / cosx(λ))
+
+	var δ = asinx(sinx(β)*cosx(ε) + cosx(β)*sinx(ε)*sinx(λ))
+
+	if α < 0 {
+		α += 180
+	}
+
+	return EquatorialCoordinate{
+		ra:  α,
+		dec: δ,
+	}
+}

pkg/dusk/coordinates_test.go

@@ -1 +1,32 @@
 package dusk
+
+import (
+	"math"
+	"testing"
+)
+
+func TestConvertEclipticCoordinateToEquatorialRA(t *testing.T) {
+	// utilising the ecliptic position of the moon on the datetime provided:
+	var ec EquatorialCoordinate = ConvertEclipticCoordinateToEquatorial(d, EclipticCoordinate{λ: 133.162655, β: -3.229126, Δ: 0})
+
+	var got float64 = ec.ra
+
+	var want float64 = 134.688470
+
+	if math.Abs(got-want) > 0.15 {
+		t.Errorf("got %f, wanted %f", got, want)
+	}
+}
+
+func TestConvertEclipticCoordinateToEquatorialDec(t *testing.T) {
+	// utilising the ecliptic position of the moon on the datetime provided:
+	var ec EquatorialCoordinate = ConvertEclipticCoordinateToEquatorial(d, EclipticCoordinate{λ: 133.162655, β: -3.229126, Δ: 0})
+
+	var got float64 = ec.dec
+
+	var want float64 = 13.768368
+
+	if math.Abs(got-want) > 0.15 {
+		t.Errorf("got %f, wanted %f", got, want)
+	}
+}