Get more accurate sunrise/set times

kylecorry31 · Sep 12, 2020 · 766b57d · 766b57d
1 parent bea3bbf
commit 766b57d
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Showing 3 changed files with 26 additions and 6 deletions.
diff --git a/app/src/main/java/com/kylecorry/trailsensecore/domain/astronomy/Astro.kt b/app/src/main/java/com/kylecorry/trailsensecore/domain/astronomy/Astro.kt
@@ -356,9 +356,12 @@ internal object Astro {
         coordinate: Coordinate,
         standardAltitude: Double = -0.8333
     ): RiseSetTransitTimes {
-        val ut = ut(date).toLocalDate().atStartOfDay()
-        val sr = meanSiderealTime(julianDay(ut))
-        val sun = solarCoordinates(julianDay(ut))
+        val ut = ut0hOnDate(date)
+        val jd = julianDay(ut)
+        val longitudeNutation = nutationInLongitude(jd)
+        val eclipticObliquity = trueObliquityOfEcliptic(jd)
+        val sr = apparentSiderealTime(jd, longitudeNutation, eclipticObliquity)
+        val sun = solarCoordinates(jd)
         val times = riseSetTransitTimes(
             coordinate.latitude,
             coordinate.longitude,
@@ -528,6 +531,22 @@ internal object Astro {
     private fun square(a: Double): Double {
         return a * a
     }
+
+
+    private fun ut0hOnDate(date: ZonedDateTime): LocalDateTime {
+        val localDate = date.toLocalDate()
+
+        for (i in -1..1){
+            val ut0h = ut(date.plusDays(i.toLong())).toLocalDate().atStartOfDay()
+            val local0h = utToLocal(ut0h, date.zone)
+            if (localDate == local0h.toLocalDate()){
+                return ut0h
+            }
+        }
+
+        return ut(date).toLocalDate().atStartOfDay()
+    }
+
 }
 
 data class AstroCoordinates(val declination: Double, val rightAscension: Double)

diff --git a/app/src/main/java/com/kylecorry/trailsensecore/domain/time/TimeExtensions.kt b/app/src/main/java/com/kylecorry/trailsensecore/domain/time/TimeExtensions.kt
@@ -28,8 +28,8 @@ fun Instant.toZonedDateTime(): ZonedDateTime {
 
 fun LocalDateTime.plusHours(hours: Double): LocalDateTime {
     val h = hours.toLong()
-    val m = ((hours % 1) * 60).toLong()
-    val s = (hours * 60) % 1
+    val m = (hours % 1) * 60
+    val s = (m % 1) * 60
     val ns = (1e9 * s).toLong()
-    return this.plusHours(h).plusMinutes(m).plusNanos(ns)
+    return this.plusHours(h).plusMinutes(m.toLong()).plusNanos(ns)
 }
diff --git a/app/src/test/java/com/kylecorry/trailsensecore/domain/astronomy/AstroTest.kt b/app/src/test/java/com/kylecorry/trailsensecore/domain/astronomy/AstroTest.kt
@@ -240,4 +240,5 @@ class AstroTest {
         assertEquals(-7.78507, coords.declination, 0.0001)
         assertEquals(-161.61917, coords.rightAscension, 0.0001)
     }
+
 }
-Original file line number
+Diff line change
@@ Expand Up / @@ -240,4 +240,5 @@ class AstroTest { @@
             assertEquals(-7.78507, coords.declination, 0.0001)
             assertEquals(-161.61917, coords.rightAscension, 0.0001)
         }
     }