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PAHFIT / pahfit

Model Decomposition for Near- to Mid-Infrared Spectroscopy of Astronomical Sources
https://pahfit.readthedocs.io/
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Multiple spectra from different instruments w/ overlapping wavelengths #29

Open karllark opened 5 years ago

karllark commented 5 years ago

Possibly could be done by artificially shifting the spectra from different instruments to non-overlapping wavelengths (w/ appropriate scalings) and constraining the common features for the fitting. Then the same fitting machinery should work.

jdtsmith commented 5 years ago

Shifting spectra in wavelength changes integrated feature strength (in the same way as redshift) and wouldn't work for smooth functions like blackbodies. Is there any reason we can't just fit a suite of parallel models with absolute ties between the "same" lines/features (in terms of integrated strength)? The modeler doesn't care about "wavelength" after all. Not sure how continuum would get treated (we need to demand it is "continuous" and identical in the overlap regions).

This would definitely stress the parameter constraint apparatus of the model framework. This is a long range enhancement I'd guess. It definitely relates closely to the issue of spectral stitching discussed in #16. How much of this is PAHFIT's job? Reasonable people can disagree.

karllark commented 5 years ago

I agree with all your comments. :-)

jdtsmith commented 1 year ago

This old issue leads to AstroPy's JointFitter and related "fit overlapping spectra in parallel" ideas. Currently not implemented given the limitations of the joint fitter, but part of the new model plan.