Open edetoc opened 1 year ago
Hey, thanks for reaching out and letting me know!
I was able to reproduce this behaviour, seems like it consistenly is off by a few minutes and also has the incorrect Azimuth and Elevation data. (Time on the right side is UTC)
This is weird since I am pretty sure that I cross compared with N2YO and other pages a lot when I initially wrote the program. But it is possible that I introduced an error somewhere that accumulated over time. According to the library used the error should not be larger than 1KM:
The SGP4 implementation is accurate in the KM range meaning the calculated position of an object can be off by around 1 km
https://github.com/1manprojects/one_Sgp4/blob/master/README.md#accuracy
I would assume that this is an error introduced by me and not the library and that you can safely implement the pass prediciton in your program. But I would have to do some further digging into it to confirm this suspicion and hopefully fix my bug as well.
Sadly I have a lot of other projects going on at the time. I am not sure when I will get around to fixing this.
Thanks a lot for your response. I did some more experimentation on my side. I wrote a simple app that is calling :
List
observer coordinates in below screenshot is the Eiffel tower: One_Sgp4.Coordinate observer = new Coordinate(48.8583, 2.2945, 0); // tour eiffel
I am getting the TLE for the ISS from Celestrak: https://celestrak.org/NORAD/elements/gp.php?CATNR=25544
I have compared the passes (all passes, in local time) obtained in my app with N2YO and I can see pretty similar results:
I don't see anything wrong in your code (btnCalc_Click). I see you're using a different source for the TLE. Could it be the root cause why you're seeing inaccurate results ?
Nice App, Congratulations !
I am also using OneSgp4 library in my app and I'm considering adding passes predictions. I can see you have this in your app:
https://github.com/JKamue/SatWatcher/blob/3d1bcdd346b2d1e7dd07e6aa7ab2edcb7ba2b4f8/SatWatcher/Forms/PassCalculator.cs#L52
I just tried to compare the predictions obtained with your app with what I get from Heavens-above.com (for Paris). for each pass I can see a few minutes difference. I have underlined some of them in the screenshot below (on the left is heavens-above.com, your app is on the right). Have you noticed that too ?
thanks !