jsauve/aasharp

Astronomical Algorithms in C#

aasharp's Issues

AASharp.AASCoordinateTransformation.Equatorial2Horizontal probably wrong implementation

@jsauve
@elendil-software
@NameOfTheDragon

The AASharp.AASCoordinateTransformation.Equatorial2Horizontal method is incorrectly implemented.
It gives definitely wrong result for Polaris azimuth coordinate.
We all know that Polaris has a "special place" on the night sky and its azimuth coordinate regardless of the current geographic location must be always near 359° (or 0° - 1°, but always between these values).

But the current implementation gives cca 179° for Polaris azimuth, which is impossible!

Used following code to test it:

using System;
using System.Globalization;
using AASharp;

namespace ABC {
    class Program {
        static void Main(string[] args) {
            // constants
            var latitude = 47.832301400;    // enter your latitude in decimal degrees
            var longitude = 17.668490900;   // enter your longitude in decimal degrees
            var ra = 2.53030404466667;      // Polaris RA in decimal hours
            var de = 89.26410897;           // Polaris DE in decimal degrees

            // calculated values
            var utcNow = DateTime.UtcNow;
            var jd1 = new AASDate(utcNow.Year, utcNow.Month, utcNow.Day, utcNow.Hour, utcNow.Minute, utcNow.Second, true).Julian;
            var gmst = AASSidereal.MeanGreenwichSiderealTime(jd1);
            var lmst = gmst + AASCoordinateTransformation.DegreesToHours(longitude);
            var lha = lmst - ra;
            var coord = AASCoordinateTransformation.Equatorial2Horizontal(lha, de, latitude);

            // display values
            Console.WriteLine("{0,-30}{1}", "UTC",                          utcNow.ToString(@"HH\:mm\:ss", CultureInfo.InvariantCulture) );
            Console.WriteLine("{0,-30}{1}", "Greenwich mean sidereal time", TimeSpan.FromHours(gmst).ToString(@"hh\:mm\:ss", CultureInfo.InvariantCulture) );
            Console.WriteLine("{0,-30}{1}", "Local mean sidereal time",     TimeSpan.FromHours(lmst).ToString(@"hh\:mm\:ss", CultureInfo.InvariantCulture) );
            Console.WriteLine("{0,-30}{1}", "Local hour angle",             TimeSpan.FromHours(lha).ToString(@"hh\:mm\:ss", CultureInfo.InvariantCulture) );
            Console.WriteLine("{0,-30}{1}", "Azimuth",                      FormatDMS(coord.X) );
            Console.WriteLine("{0,-30}{1}", "Altitude",                     FormatDMS(coord.Y) );

            Console.Write(Environment.NewLine);
        }

        // Convert decimal degrees to DMS string
        private static string FormatDMS(double dd) {
            var ts = TimeSpan.FromHours(dd);
            return string.Format("{0:D}", ts.Days * 24 + ts.Hours) + "°" +
                string.Format("{0:D2}", ts.Minutes) + "'" +
                string.Format("{0:D2}", ts.Seconds) + "\"";
        }
    }
}

Link to SwiftAA?

Hi,

Not an issue per-se. I just discovered your code, and since I am the author of the Objective-C(++) / Swift and Javascript versions, I thought it would be cool to link to yours.

You may be interested to link back ? :-)
https://github.com/onekiloparsec/SwiftAA

Best

Is Mono Solution file still necessary ?

Hi,

I open this issue to discuss the need of the Mono solution version (AASharp.Mono.sln)

With .Net standard I'm not sure it is still necessary to keep this solution file.

Note : the solution AASharp.sln is targeting .Net Standard 2.0, .Net 4.0 and .Net 4.5. We could add .Net Standard 1.6 to support Mono 4.6

Helper function to return constellation from equatorial coordinates

Hi @elendil-software @jsauve !

As the title says, that function would be really useful.
There is a ready to use JavaScript application available here.
Demo page is here.

It would be nice to port this to our lovely AASharp.

BR,

Ladislav

AASharp.Extension

@jsauve
I created a new repository for extension to AASharp : https://github.com/elendil-software/AASharp.Extension

• I already put there a few classes that I initially pushed on AASharp.
• On AASharp I have have set this classes as "Obsolete"

And I reported the modifications of AA+ 1.98 and 1.99. I will build the NuGet package soon. I have some problem with my CI server. As soon I solve that I build the package.

Julien

Used licensing

Would you possibly change the used license LGPL-3.0 to MIT_License?
It would make it easier to use in other projects.

Height parameter was removed from CAARiseTransitSet2::Calculate in the AA+ v2.36

Since v2.36 (12 September 2021) of AA+, the Height parameter was removed from the CAARiseTransitSet2::Calculate & CalculateMoon methods. But it is not ported yet to AASharp.

The parameter was removed and replaced by 0 (Zero) in all occurrences.

The link for the announcement : https://naughter.wordpress.com/2021/09/12/aa-v2-36/

Note that CAARiseTransitSet2::CalculateMoon algorithm has changed.

Thanks.

Can't open the solution

Hi @jsauve

Cannot open the AASharp.sln solution, at least in Visual Studio 2013.

However, as far as I checked the source code, it looks a very good Astro library, with rich function set!

Did u consider to make it available as a nuget package at www.nuget.org ?

Implementation of the last AA+ additions

Hi @jsauve

I implemented the last AA+ additions on the develop branch. If you want to have a look before I merge it on Master and release the NuGet package.

• CAAMoonPhases2
• CAAMoonNodes2
• CAAMoonPerigeeApogee2
• CAAMoonMaxDeclinations2
• CAAEquinoxesAndSolstices2
• CAARiseTransitSet2

Regards,

Julien

Qingming Festival

Hello,

What amazing repository !

I'm searching a way to calculate the 5th solar term for the chinese calendar.
I know there is some calculation to do in order to get the gregorian date, but I have no idea to do this :/.
I think your libraries can do this, but have you any idea ?

If you can help we with your project it will be so cool ;)

Some link :
https://en.wikipedia.org/wiki/Solar_term
https://en.wikipedia.org/wiki/Qingming_Festival
http://www.math.nus.edu.sg/aslaksen/gem-projects/hm/Chinese_Calendar.pdf

Best regards,

Shaenn

Uranus has copy of Neptune coefficients

AASharp/Src/AASharp/AASUranus.cs

Line 9 in 4f977c6

static readonly VSOP87Coefficient[] g_L0NeptuneCoefficients =

DaysInMonth in AASDate should checks that month parameter is between 1 and 12

The validation is not correct, an exception is thrown if month is lower than 1 AND greater than 12. Should be month is lower than 1 OR greater than 12