Satellite tracking - plot position on 2D Earth map

[thor36]

Hello. :tiphat: I have a question which hopefully fits this sub-forum. In case it doesn't please let me know and I will fix it in any way possible :thumbup:

I would like to create a simple satellite tracking software, that will compute the position of a satellite at any time, and show its location on a 2D map of Earth surface.

Let's assume it is possible to find online position of a satellite in the Earth-centered inertial (ECI) coordinate frame ( in form of TLE for example ) and use some method to propagate its state to a moment in future. Then if I want to plot the position on Earth map, I will need to know orientation of Earth at a given moment in relation to the original ECI frame, probably with the help of ECEF (Earth-Centered, Earth-Fixed).

And here come the questions, how do I :

- transform from ECI to ECEF
- take in account Earth precession and nutation
- do the proper time conversion, to also involve leap years, leap seconds, added seconds...

I would like to get as precise results as possible, and thus I know it can not be as simple as putting a few mathematical functions together and let it do the work. It would be used for satellite tracking, orbit prediction etc.. There are probably different ways to achieve it, with different properties as well, so I would like to learn as much about it as possible. Thank you

 

[SolarLiner]

*cough* http://www.stoff.pl/ *cough*
But if you really want to do it yourself then I don't really know what to do.

 

[thor36]

*cough* http://www.stoff.pl/ *cough*
But if you really want to do it yourself then I don't really know what to do.

Thank you for the link, I appreciate it. I have played with Orbitron for a while some time ago But yes, I really do wish to do something on my own.

 

[Urwumpe]

Thank you for the link, I appreciate it. I have played with Orbitron for a while some time ago But yes, I really do wish to do something on my own.

The best you could do for a start, is to calculate a projection matrix from ECEF to J2000 ECI - thats pretty simple for the start, since it is just a function of time.

The opposite way, is then "simply" to invert the matrix = turn the projection around.

 

[thor36]

The best you could do for a start, is to calculate a projection matrix from ECEF to J2000 ECI - thats pretty simple for the start, since it is just a function of time.

The opposite way, is then "simply" to invert the matrix = turn the projection around.

Thank you for your reply. Are you talking about something like this ? I have stumbled upon this article yesterday. It seems to be describing what I am looking for. However it uses a lot of terminology that I am unfamiliar with. It also doesn't tell a lot about precision of this technique and where the equations come from ( I need to be confident that I am implementing the right procedures ). I would still like to address all of my initial issues. Any comment or tips for where to look for answers will be very much appreciated.