feat: Added ConvertEquatorialCoordinateToHorizontal().

coverage.txt

@@ -1,10 +1,10 @@
 mode: atomic
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:10.30,12.2 1 663
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:14.30,16.2 1 106
+github.com/observerly/dusk/pkg/dusk/trigonometry.go:10.30,12.2 1 673
+github.com/observerly/dusk/pkg/dusk/trigonometry.go:14.30,16.2 1 116
 github.com/observerly/dusk/pkg/dusk/trigonometry.go:18.44,20.2 1 301
 github.com/observerly/dusk/pkg/dusk/trigonometry.go:22.30,24.2 1 7
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:26.31,28.2 1 34
-github.com/observerly/dusk/pkg/dusk/trigonometry.go:30.31,32.2 1 26
+github.com/observerly/dusk/pkg/dusk/trigonometry.go:26.31,28.2 1 36
+github.com/observerly/dusk/pkg/dusk/trigonometry.go:30.31,32.2 1 28
 github.com/observerly/dusk/pkg/dusk/trigonometry.go:34.31,36.2 1 3
 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
@@ -19,21 +19,22 @@ 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 6
-github.com/observerly/dusk/pkg/dusk/astrometry.go:12.52,16.12 2 2
-github.com/observerly/dusk/pkg/dusk/astrometry.go:20.2,20.11 1 2
-github.com/observerly/dusk/pkg/dusk/astrometry.go:16.12,18.3 1 2
+github.com/observerly/dusk/pkg/dusk/astrometry.go:12.52,16.12 2 4
+github.com/observerly/dusk/pkg/dusk/astrometry.go:20.2,20.11 1 4
+github.com/observerly/dusk/pkg/dusk/astrometry.go:16.12,18.3 1 4
 github.com/observerly/dusk/pkg/dusk/coordinates.go:37.108,56.12 10 2
 github.com/observerly/dusk/pkg/dusk/coordinates.go:60.2,63.3 1 2
 github.com/observerly/dusk/pkg/dusk/coordinates.go:56.12,58.3 1 2
-github.com/observerly/dusk/pkg/dusk/epoch.go:31.48,36.2 2 71
+github.com/observerly/dusk/pkg/dusk/coordinates.go:76.148,91.2 6 2
+github.com/observerly/dusk/pkg/dusk/epoch.go:31.48,36.2 2 73
 github.com/observerly/dusk/pkg/dusk/epoch.go:43.45,45.2 1 70
-github.com/observerly/dusk/pkg/dusk/epoch.go:53.60,65.13 6 4
-github.com/observerly/dusk/pkg/dusk/epoch.go:69.2,81.13 5 4
-github.com/observerly/dusk/pkg/dusk/epoch.go:85.2,85.12 1 4
+github.com/observerly/dusk/pkg/dusk/epoch.go:53.60,65.13 6 6
+github.com/observerly/dusk/pkg/dusk/epoch.go:69.2,81.13 5 6
+github.com/observerly/dusk/pkg/dusk/epoch.go:85.2,85.12 1 6
 github.com/observerly/dusk/pkg/dusk/epoch.go:65.13,67.3 1 1
 github.com/observerly/dusk/pkg/dusk/epoch.go:81.13,83.3 1 1
-github.com/observerly/dusk/pkg/dusk/epoch.go:94.74,102.11 4 3
-github.com/observerly/dusk/pkg/dusk/epoch.go:106.2,106.17 1 3
+github.com/observerly/dusk/pkg/dusk/epoch.go:94.74,102.11 4 5
+github.com/observerly/dusk/pkg/dusk/epoch.go:106.2,106.17 1 5
 github.com/observerly/dusk/pkg/dusk/epoch.go:102.11,104.3 1 0
 github.com/observerly/dusk/pkg/dusk/epoch.go:115.65,126.2 4 31
 github.com/observerly/dusk/pkg/dusk/epoch.go:134.73,142.2 3 28

pkg/dusk/coordinates.go

@@ -62,3 +62,30 @@ func ConvertEclipticCoordinateToEquatorial(datetime time.Time, ec EclipticCoordi
 		dec: δ,
 	}
 }
+
+/*
+	ConvertEquatorialCoordinateToHorizontal()
+
+	@param datetime - the datetime of the observer (in UTC)
+	@param longitude - is the longitude (west is negative, east is positive) in degrees of some observer on Earth
+	@param latitude - is the latitude (south is negative, north is positive) in degrees of some observer on Earth
+	@param equatorial coordinate of type EquatorialCoordiate { ra, dec }
+	@returns the equivalent horizontal coordinate for the given observers position
+	@see eq13.5 and eq.6 p.93 of Meeus, Jean. 1991. Astronomical algorithms. Richmond, Va: Willmann-Bell.
+*/
+func ConvertEquatorialCoordinateToHorizontal(datetime time.Time, longitude float64, latitude float64, eq EquatorialCoordinate) HorizontalCoordinate {
+	var LST float64 = GetLocalSiderealTime(datetime, longitude)
+
+	var ra float64 = GetHourAngle(eq.ra, LST)
+
+	var dec float64 = eq.dec
+
+	var alt = asinx(sinx(dec)*sinx(latitude) + cosx(dec)*cosx(latitude)*cosx(ra))
+
+	var az = acosx((sinx(dec) - sinx(alt)*sinx(latitude)) / (cosx(alt) * cosx(latitude)))
+
+	return HorizontalCoordinate{
+		a: alt,
+		A: az,
+	}
+}

pkg/dusk/coordinates_test.go

@@ -30,3 +30,27 @@ func TestConvertEclipticCoordinateToEquatorialDec(t *testing.T) {
 		t.Errorf("got %f, wanted %f", got, want)
 	}
 }
+
+func TestConvertEquatorialCoordinateTHorizontalAltitude(t *testing.T) {
+	var hz HorizontalCoordinate = ConvertEquatorialCoordinateToHorizontal(datetime, longitude, latitude, EquatorialCoordinate{ra: 88.7929583, dec: 7.4070639})
+
+	var got float64 = hz.a
+
+	var want float64 = 72.800882
+
+	if math.Abs(got-want) > 0.00001 {
+		t.Errorf("got %f, wanted %f", got, want)
+	}
+}
+
+func TestConvertEquatorialCoordinateTHorizontalAzimuth(t *testing.T) {
+	var hz HorizontalCoordinate = ConvertEquatorialCoordinateToHorizontal(datetime, longitude, latitude, EquatorialCoordinate{ra: 88.7929583, dec: 7.4070639})
+
+	var got float64 = hz.A
+
+	var want float64 = 134.397750
+
+	if math.Abs(got-want) > 0.00001 {
+		t.Errorf("got %f, wanted %f", got, want)
+	}
+}