Redesigned the Altitude and Azimuth readings to use the Right Ascension and Declination co-ordinates and perform the transformation using the date and site details from the scope. This will correct the problem of the Altitude reading from the handset being incorrect.

2019-05-18 23:50:55 +01:00
parent cf5a6c72fe
commit cf28ecc7c2
9 changed files with 506 additions and 19 deletions
@@ -0,0 +1,165 @@
+using System;
+using ASCOM.Utilities;
+
+namespace ASCOM.Meade.net
+{
+    public class EquatorialCoordinates
+    {
+        public double RightAscension { get; set; }
+        public double Declination { get; set; }
+    }
+
+    public class HorizonCoordinates
+    {
+        public double Altitude { get; set; }
+        public double Azimuth { get; set; }
+    }
+
+
+    public class AltitudeData
+    {
+        public DateTime UtcDateTime { get; set; }
+        public double SiteLatitude { get; set; }
+        public double SiteLongitude { get; set; }
+        public EquatorialCoordinates equatorialCoordinates { get; set; }
+    }
+
+    public class AstroMaths
+    {
+
+        //returns the decimal hour angle for given right ascension on a given datetime for a given logitude.
+        public double RightAscensionToHourAngle(DateTime utcDateTime, double longitude, double rightAscension)
+        {
+            var ut = DateTimeToDecimalHours( utcDateTime);
+            var gst = UTtoGST( utcDateTime);
+            var lst = GSTtoLST( gst, longitude);
+            var raHours = rightAscension;
+            var h1 = lst - raHours;
+            var h = h1;
+
+            if (h < 0)
+                h = h + 24;
+
+            return h;
+        }
+
+        public HorizonCoordinates ConvertEqToHoz(double hourAngle, double latitude, EquatorialCoordinates raDec)
+        {
+            var h = hourAngle * 15;
+            var h1 = DegreesToRadians(h);
+            var d = DegreesToRadians(raDec.Declination);
+            var lat = DegreesToRadians(latitude);
+            var sinA = Math.Sin(d) * Math.Sin(lat) + Math.Cos(d) * Math.Cos(lat) * Math.Cos(h1);
+
+            var y = -Math.Cos(d) * Math.Cos(lat) * Math.Sin(h1);
+            var x = Math.Sin(d) - Math.Sin(lat) * sinA;
+            var upperA = Math.Atan2(y, x);
+            var upperB = RadiansToDegrees(upperA);
+
+            var horizonCoordinates = new HorizonCoordinates();
+            horizonCoordinates.Altitude = RadiansToDegrees(Math.Asin(sinA));
+
+            horizonCoordinates.Azimuth = upperB;
+
+            if (upperB < 0)
+            {
+                horizonCoordinates.Azimuth = 360 + horizonCoordinates.Azimuth;
+            }
+            
+            return horizonCoordinates;
+        }
+
+
+        //todo convert to extension method
+        public double DegreesToRadians(double degrees)
+        {
+            return (Math.PI / 180) * degrees;
+        }
+
+        //todo convert to extension method
+        public double RadiansToDegrees(double radians)
+        {
+            double degrees = (180 / Math.PI) * radians;
+            return (degrees);
+        }
+
+        //todo convert to extension method
+        public double DateTimeToDecimalHours( DateTime utcDateTime)
+        {
+            double sec = utcDateTime.Second;
+            double min = utcDateTime.Minute;
+            double hour = utcDateTime.Hour;
+			
+            var a = Math.Abs(sec) / 60;
+            var b = (Math.Abs(min) + a) / 60;
+            var c = Math.Abs(hour) + b;
+
+            var d = c;
+
+            if ((hour < 0) || (min < 0) || (sec < 0))
+                d = -c;
+
+            return d;
+        }
+
+        //todo convert to extension method
+        public double UTtoGST(DateTime utcDateTime)
+        {
+            Util util = new Util();
+
+            var jd = util.DateUTCToJulian(utcDateTime) - 0.5;
+            if ((jd % 1) <= 0.5 )
+                jd = Math.Floor( jd );
+            else
+                jd = Math.Floor( jd ) + 0.5;
+
+            var s = jd - 2451545.0;
+            var t = s / 36525.0;
+            var t0 = 6.697374558 + (2400.051336 * t ) +(0.000025862 * (t * t) );
+
+            while (t0 < 0)
+            {
+                t0 += 24;
+            }
+
+            while (t0 >= 24)
+            {
+                t0 -= 24;
+            }
+			
+            var ut = DateTimeToDecimalHours(utcDateTime);
+            var a = ut * 1.002737909;
+
+            var t1 = t0 + a;
+
+            while (t1 < 0)
+            {
+                t1 += 24;
+            }
+
+            while (t1 >= 24)
+            {
+                t1 -= 24;
+            }
+
+            return t1;
+        }
+
+        public double GSTtoLST(double gst, double longitude)
+        {
+            var l = longitude/ 15;
+
+            var lst = gst + l;
+            while (lst < 0 )
+            {
+                lst += 24;
+            }
+            while (lst >= 24)
+            {
+                lst -= 24;
+            }
+
+            return lst;
+        }
+    }
+}