Update MIRI detector cross artifact model; fixes #415

[mperrin]

See discussion at #415: the model for the MIRI cross artifact (detector internal diffraction) turned out to be low in webbpsf compared to the MIRI CDP PSFs. I am not sure how this was not caught before. I derived empirical scaling factors that bring them into agreement.

Relatively simple PR in terms of the code; all the effort was in figuring out the appropriate scale factors and verifying things are now working as intended.

This PR assumes that the MIRI CDP PSFs can be taken as a reliable reference for the cross artifact amplitudes vs wavelength.

Before (using original amplitudes):

See difference column at right, then compare to the "after" version of this plot, below..

After (using rescaling factors):

Same plot scale as above.

Horizontal cuts across the PSFs show excellent quantitative agreement now (unlike the prior plots visible in #415):

[mperrin]

@merope82 would you be so kind as to take a look at the plots on this update to WebbPSF, please? It's pretty quick and dirty and ad hoc, but I think suffices for current purposes.

[codecov]

Codecov Report

Merging #417 (b642091) into develop (67c7c18) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #417      +/-   ##
===========================================
+ Coverage    48.59%   48.62%   +0.02%     
===========================================
  Files           14       14              
  Lines         5772     5775       +3     
===========================================
+ Hits          2805     2808       +3     
  Misses        2967     2967              

Impacted Files	Coverage Δ
webbpsf/distortion.py	95.23% <100.00%> (+0.11%)	⬆️

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[merope82]

Hi @mperrin! They do look significantly better; possibly even better at approximating the artifact than the model. Obviously scaling is scaling. As you can see, the diffraction also widens the PSF features (basically yields a halo around all higher flux regions), which the scaling does not subtract.

…

On Wed, Feb 24, 2021 at 12:07 PM Marshall Perrin ***@***.***> wrote: *External Email* @merope82 <https://github.com/merope82> would you be so kind as to take a look at the plots on this update to WebbPSF, please? It's pretty quick and dirty and ad hoc, but I think suffices for current purposes. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#417 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AH7CDOQLCEZ5HDHDNOA2NCDTAVE5ZANCNFSM4YFBZKNQ> .

[shanosborne]

Looks good to me! I'm glad to see we got some more accurate numbers