Astronomy/MeadeGeneric
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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.

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This commit is contained in:
Colin Dawson
2019-05-18 23:50:55 +01:00
parent cf5a6c72fe
commit cf28ecc7c2
9 changed files with 506 additions and 19 deletions
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Meade.net.Telescope/AstroMaths.cs
+165
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@@ -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;
}
}
}
Meade.net.Telescope/Meade.net.Telescope.csproj
+1
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@@ -81,6 +81,7 @@
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="AstroMaths.cs" />
<Compile Include="StringExtensions.cs" />
<Compile Include="Telescope.cs" />
<Compile Include="Properties\AssemblyInfo.cs" />
Meade.net.Telescope/Telescope.cs
+44 -12
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@@ -98,6 +98,8 @@ namespace ASCOM.Meade.net
/// </summary>
private AstroUtils astroUtilities;
private AstroMaths astroMaths;
/// <summary>
/// Variable to hold the trace logger object (creates a diagnostic log file with information that you specify)
/// </summary>
@@ -117,7 +119,9 @@ namespace ASCOM.Meade.net
connectedState = false; // Initialise connected to false
utilities = new Util(); //Initialise util object
astroUtilities = new AstroUtils(); // Initialise astro utilities object
//TODO: Implement your additional construction here
astroMaths = new AstroMaths();
tl.LogMessage("Telescope", "Completed initialisation");
}
@@ -403,21 +407,45 @@ namespace ASCOM.Meade.net
{
get
{
//todo firmware bug in 44Eg, :GA# is returning the dec, not the altitude!
var result = SharedResources.SendString(":GA#");
//:GA# Get Telescope Altitude
//Returns: sDD* MM# or sDD*MM’SS#
//The current scope altitude. The returned format depending on the current precision setting.
var altAz = CalcAltAzFromTelescopeEqData();
tl.LogMessage("Altitude", $"{altAz.Altitude}");
return altAz.Altitude;
var alt = utilities.DMSToDegrees(result);
tl.LogMessage("Altitude", $"{alt}");
return alt;
////todo firmware bug in 44Eg, :GA# is returning the dec, not the altitude!
//var result = SharedResources.SendString(":GA#");
////:GA# Get Telescope Altitude
////Returns: sDD* MM# or sDD*MM’SS#
////The current scope altitude. The returned format depending on the current precision setting.
//var alt = utilities.DMSToDegrees(result);
//tl.LogMessage("Altitude", $"{alt}");
//return alt;
//tl.LogMessage("Altitude Get", "Not implemented");
//throw new ASCOM.PropertyNotImplementedException("Altitude", false);
}
}
private HorizonCoordinates CalcAltAzFromTelescopeEqData()
{
var altitudeData = SharedResources.Lock(() => new AltitudeData
{
UtcDateTime = this.UTCDate,
SiteLongitude = this.SiteLongitude,
SiteLatitude = this.SiteLatitude,
equatorialCoordinates = new EquatorialCoordinates()
{
RightAscension = this.RightAscension,
Declination = this.Declination
}
});
double hourAngle = astroMaths.RightAscensionToHourAngle(altitudeData.UtcDateTime, altitudeData.SiteLongitude,
altitudeData.equatorialCoordinates.RightAscension);
var altAz = astroMaths.ConvertEqToHoz(hourAngle, altitudeData.SiteLatitude, altitudeData.equatorialCoordinates);
return altAz;
}
public double ApertureArea
{
get
@@ -467,15 +495,19 @@ namespace ASCOM.Meade.net
{
get
{
var result = SharedResources.SendString(":GZ#");
//var result = SharedResources.SendString(":GZ#");
//:GZ# Get telescope azimuth
//Returns: DDD*MM#T or DDD*MM’SS#
//The current telescope Azimuth depending on the selected precision.
double az = utilities.DMSToDegrees(result);
//double az = utilities.DMSToDegrees(result);
tl.LogMessage("Azimuth Get", $"{az}");
return az;
//tl.LogMessage("Azimuth Get", $"{az}");
//return az;
var altAz = CalcAltAzFromTelescopeEqData();
tl.LogMessage("Azimuth Get", $"{altAz.Azimuth}");
return altAz.Azimuth;
}
}