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Keck-DataReductionPipelines / KPF-Pipeline

KPF-Pipeline
https://kpf-pipeline.readthedocs.io/en/latest/
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LFC masters are using etalon data to derive WLS #916

Open shalverson opened 3 months ago

shalverson commented 3 months ago

The LFC master stacks are using etalon spectra to derive the WLS. This has been diagnosed a few ways, 1) by the SCI-OBJ keywords in the header of the LFC WLS master 2) by looking at the etalon spectrum for a given day and measuring the apparently free spectral range (the etalon line spacing is 30 GHz natively), and 3) seeing the individual LFC-calibrated orders 'shrink' in wavelength by ~30%. Since the WLS code is forcing the detected peaks in the LFC master file to be 20 GHz apart, the WLS will be compressed by a factor of 20GHz/30GHz anytime the etalon data is unintentionally used.

Examples plots showing this are below, in no particular order:

image

Screenshot 2024-06-12 at 1 16 30 PM Screenshot 2024-06-12 at 1 20 00 PM

Here's an example of what the etalon line spacing curve should look like: image

shalverson commented 3 months ago

In addition to fixing the masters, we also need to add some additional QCs in the WLS code to independently identify if the provided spectrum is correct or not. @aaronhouseholder let's discuss some quick checks that we can use so that the WLS code knows not to produce a fit when it's handed the wrong source