Move ecliptic obliquity to angle

Author: ncke

Sources/SwiftAstro/Units/Angle.swift

@@ -191,6 +191,17 @@ extension SwiftAstro.Angle {
 
 }
 
+// MARK: - Mean Obliguity Of The Ecliptic
+
+extension SwiftAstro.Angle {
+    
+    /// The mean obliquity of the ecliptic in the standard equinox of J2000.
+    public static let meanObliquityOfEclipticAtJ2000 = SwiftAstro.Angle(
+        degrees: 23.43929111111111
+    )
+
+}
+
 // MARK: - Operators
 
 extension SwiftAstro.Angle {

Sources/SwiftAstro/Units/Time+Ecliptic.swift

@@ -4,17 +4,12 @@ import Foundation
 
 extension SwiftAstro.Time {
 
-    /// The mean obliquity of the ecliptic in the standard equinox of J2000.
-    public static let meanObliquityOfEclipticAtJ2000 = SwiftAstro.Angle(
-        degrees: 23.43929111111111
-    )
-
     /// The mean obligquity of the ecliptic.
     /// - Note : See Equation 21.3, Meeus (1991), p. 135.
     public var meanObliquityOfEcliptic: SwiftAstro.Angle {
         let U = 0.1 * self.julianMilleniaSinceEpoch(.J2000)
 
-        let e0 = Self.meanObliquityOfEclipticAtJ2000.degrees
+        let e0 = SwiftAstro.Angle.meanObliquityOfEclipticAtJ2000.degrees
         - 4680.93 * U / 3600.0
         - 1.55 * pow(U, 2.0) / 3600.0
         + 1999.25 * pow(U, 3.0) / 3600.0