Converting from TEME to EME2000 Frame

Orekit usage
1

I am reading in a TLE and generating ephemeris for use in other calculations but I need the ephemeris in an ECI (EME2000) frame. I am currently doing this with a Matlab script but wanted to see if Orekit has a method to change frame output. Thanks.

2

Hi @StephenC,

Given an Orekit TLEPropagator and an Orekit AbsoluteDate , just use:

TimeStampedPVCoordinates PV = TLEPropagator.getPVCoordinates(date, FramesFactory.getEME2000())

To have your PV in EME2000.
Is that what you’re looking for ?

Maxime

3

Yes, to be compatible with other calculations I need to have the satellite position/velocity in EME2000.

4

hi @StephenC,

To generate ephemeris from a propagator (in your case, a TLEPropagator), you should use the ephemeris mode of the propagator :

propagator.setEphemerisMode();
propagator.propagate(startDate, endDate);
BoundedPropagator bounded = propagator.getGeneratedEphemeris();

Once you have your BoundedPropagator object, it is possible to generate ephemeris with the time step and the frame you want with a loop on the BoundedPropagator that uses the method that MaximeJ mentionned.

Hope it can help you,

Romaric

5

Ephemeris mode won’t hurt with analytical propagators (e.g. TLEPropagator) but it won’t help either. (Ephemeris mode is needed when using integrated propagators.)