AngularRaDec OD problem with big ΔP(m)

Orekit usage
1

Hello everyone,
For some time I have been struggling with TDM based OD using your tutorials. For my own purpose I also wanted to get initial conditions from TLE. Unfortunately I ran into a problem with big ΔP(m) such as 70655560065.9505m and therefore not converging solution. First, I tried a solution given in post about post about TLE OD tutorial but I failed to fix this problem. I also tried to transform measurements from EME2000 to TEME but it also didn’t work.
Is it a problem with initial conditions or maybe with measurements?

(reference frame of measurements is EME2000 and TLE epoch is almost the same as measurements)
EDIT1: I am performing OD of Lares norad: 38077

2

Hi @mahromir,

Welcome to the forum.

Could you share some code with us? Without it, it’s going to be hard to help you.

Be careful the station/telescope latitude/longitude/altitude must be given in radians and not in degrees in Orekit.

Maxime

3

Hi Maxime, thanks for your response. I typed wrong coordinates for my station. Now everything works perfectly. I find Numerical OD tutorial very fun and easy to play with.
After some time spent on this tutorial I would like to ask, whether observation points with high residuals are filtered out during subsequent interations. I would like to get those filtered measurements and perform OD again.
Is it possible to get those measurements from estimator or should I make my own filter?

Best
Marek

4

Hi @mahromir,

You’re welcome. Happy to see you fixed your problem.

They are filtered out if you’ve set up an OutlierFilter for those measurements (see here in the tutorial).
From one iteration to the other, the OD algorithm re-examines all the measurements, computes their residuals, and the OutlierFilterrejects those with high residuals.
(not sure that answers your question)

I think you can get them yes.
When you loop on the estimated measurements of the last iteration (see for example here), you can get the rejected EstimatedMeasurements by using method getStatus() which will return either PROCESSED or REJECTED.

Best,
Maxime

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