Dear Jonas,

Some quick feedback, I am on a conference.

The variables that you can retrieve using ARTS-OEM so far are mainly atmospheric quantities. To handle instrument variables I maonly left for the future.

A constant frequency switch could be handled by shifting the transitions as you tried to do. But frequency shifts are in fact an instrument parameter, and moving the transitions will not work for frequency stretch. So it seems to be time to implement a general way to handle instrument variables. I will discuss with Simon, that is also here at the conference.

For the moment I suggest that you do repeated linear inversions. And adjusting your instrument frequencies after each linear inversion. This should work with your extension of xaStandard. After some iterations turn off the frequency switch and make a final inversion.

Kind regards,


On 2018-09-17 17:22, Jonas Hagen wrote:
Hello ARTS Developers,

I'm trying to retrieve the Frequnecy Shift along with Wind with the ARTS internal retrieval. To my understanding, this should work, but support in xaStandard and x2artsStandard WSMs is missing and results in an error: "Found a retrieval quantity that is not yet handled by internal retrievals: Frequency"

For xaStandard(), the a priori Frequency Shift could easily be set to zero after line 793 of along with baseline and pointing. For x2artsStandard(), maybe a new WSV would make sense (f_shift) and the inversion_iterate_agenda would then call abs_linesShiftFrequency(f_shift), similar to the baseline stuff? I tried to implement it myself but got stuck with jacobian_quantities and indices in x2artsStandard().

Best regards,
Jonas Hagen
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