# State Vector processing

Hello,
I am very new the orbital dynamics and have been asked to process a state vector that is in a JS200 reference frame. I have available:

• position - Triple of position (x, y, z) in meters
• velocity - Triple of velocity (vx, vy, vz) in meters per second
• covariance - 6x6 covariance matrix of the standard dim-6 position-velocity vector
• covarianceExtended - 8x8 covariance matrix of the dim-8 extended state vector

Can I use orekit to determine the accuracy of my position & velocity by somehow utilizing the covariance?

I am attempting to learn Astrodynamics as I go, but I canâ€™t yet figure out the basic workflow for dealing with state vectors. Any pointers / insights / examples are much appreciated.

Thank you.

Hi @gormanst,

Welcome to the Orekit forum!

What do you mean by â€śprocessâ€ť the state vector ? Propagate it further in time or simply convert it to, say, orbital parameters ?

Somehow, yes, but you donâ€™t really need Orekit for that. If you take the square roots of the diagonal part of the matrix you will get the standard deviations of each component of your state vector, so in other terms the accuracy associated to each component.

Have you checked the tutorial page of the website, maybe this will help you getting started. You should probably start with the Frame, Time and Propagation tutorials.
There are also many examples on the Orekit Tutorials Gitlab.
If you are really new to Orekit and Astrodynamics I suggest you to start with a basic Keplerian Propagation tutorial.

Hope this helps,
Maxime

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By process I mean â€śuse state vector to calculate the accuracy of a given position/velocity + covariance.â€ť

Yes, JS200 â†’ JS2000 aka EME2000.

I am being given a state vector by my satellite regulator (they monitor it) and it includes position/velocity/covariance along with uncertainties/coefficients. Candidly, I am just trying to make some sense of what to do with my state vector. It seems to report an observed position/velocity and I am assuming that the covariance will tell me the accuracy of their observations. I want to display the accuracy so I figure I need to calculate it, and I bet itâ€™s like your trying to point out in your answer.