Aliases

[astudillo-defru]

Hi,
kima favors a 2 planets model but the posterior distribution of the orbital periods shows that one is the 1-day alias of the other. How can I prevent this?
Thank you!

[eggplantbren]

Do you know whether the ambiguity is genuine? If it is, there's nothing you can do (but it should favour a one planet model, sometimes with one period and sometimes with the other period). If it is really just an alias (and this is clear given the data), then this shouldn't happen and I can't figure out why it is happening without more information.

[astudillo-defru]

Thanks for your reply. I am (analytically) sure it is the genuine 1 day alias. In addition, the periodogram of RV residues when subtracting one of the periodicity do not show power excess at the alias periodicity. The posterior distribution of the orbital periods from kima shows both (alias) periodicities at the same time. What additional information do you need?

[j-faria]

I'm also surprised the two planet model is favoured because that means solutions with keplerians at the two periods together fit the data better.
In cases with an alias I would expect two nearly equal peaks in the period posterior but the one planet model being preferred.

There is no 3rd signal in the data?

As a 'solution' (a workaround, really) try restricting the prior to periods above 1 day.

[eggplantbren]

In addition, the periodogram of RV residues when subtracting one of the periodicity do not show power excess at the alias periodicity.

In this situation, kima should not be inferring both frequencies. Is it possible to provide the data?

[astudillo-defru]

Thank you for the support, but sorry, for the moment I can not provide the data

[eggplantbren]

Can you make a fake dataset that causes the same problem?

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