Detector for body-sat-ground station angle?


Doing some simulations of satellite visibility, and would like to event detect on the sun-sat-groundstation angle, when it is less than a certain value. I can set one up in python, but if possible I prefer to use java detectors for performance.

I was reading on the AlignmentDetector, not sure I understand the documentation, but I don’t think that can do it, right?


Hi @Petrus,

The AngularSeparationDetector looks like what you search.


I thought that initially too except he wants the propagated satellite in the middle rather than the other other observer, if I’m reading his comment correctly.


Yes, it is the angle between the satellite to sun vector and the satellite to ground vector I am looking for. My thought is to try to identify visible satellites, assuming some kind of diffuse reflection in the satellite towards the observer and seeing when this may be the geometrical case.

I could see the value in having a version of this event detector where the satellite is the center point versus one of the end points. For your purposes you could create a new event detector based on this one and just shuffle the geometry in the calculation.

Should we make a new one for this type of calculation or maybe add a different constructor which allows one to toggle if the satellite the detector is attached to is the viewer versus the viewee?

Thanks for the info, yes I could imagine this would be a bit of generic usability. I have no strong view if it is better to use AngularSeparationDetector with different constructor. It is indeed an angular separation but a different scope than what is described for the current one.

Hi @petrus.hyvonen,

Could you open an issue for this feature on the Gitlab forge ?
It would be nice to have it in Orekit, looks simple to add, we just need to agree on how to handle this to make it clear for the users.


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Added it as a suggestion in the issue system of the gitlab forge! Thanks.