Question on PropagationType


I was looking around in my propagator (in this case I’m using a NumericalPropagator) and I noticed that PropagationType is set to MEAN. Does that mean that the propagator is returning the mean orbital elements at the end of the propagation? And what about the initial state provided? Is that interpreted as an osculating orbit or as a mean orbit?

Also, I presume that by converting the ephemeris returned by an EphemerisGenerator I’ll get the osculating orbit associated with each PVCoordinates instance, right?

Hi there,

As you can see in the comments line 106 of AbstractIntegratedPropagator (parent class if NumericalPropagator) in v11.3, the PropagationType is only considered by semi analytical models.
As for your ephemeris generator, if it’s built from a NumericalPropagator it should return osculating states as well



I think it’s confusing that the NumericalPropagator sets the PropagationType to MEAN in the constructor.
Although it shouldn’t have any effect on the results I think we should change that.
@Emiliano could you please open an issue on the forge about this ?

Thanks for reporting this,

I agree with @MaximeJ, it is confusing, the PropagationType should be set to OSCULATING.
It seems that there is the same problem for the GLONASSNumericalPropagator.

Before the implementation of PropagationType enum, a flag meanOrbit was present. It was initialized to true for the NumericalPropagator. That’s why PropagationType is set to MEAN. Even if it not use for this propagator, I agree that’s confusing.

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Thanks to all of you for the detailed explanation

@MaximeJ I opened the issue on the forge as you asked

Best regards,

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Thanks @Emiliano,

If you want to provide a fix you’re very welcome :wink: