Howard Bushouse

@cshanahan1 are you good with this now that all review comments have been addressed?

@karllark I think this PR branch may need to be rebased from master. Looks like conflicts are preventing the CI tests from running.

I think the remaining CI failures, which are confined to ramp_fitting unit tests, are due to other PR's included in the stcal 1.1.0 release, and maybe fixed by #6949 once...

OK, #6949 has now been merged to update the truth values in the unit tests that were causing CI failures. So one more rebase to kickoff the tests again.

@stscijgbot-jp

Because the `_s2d` data are rectified, both spatially and in wavelength, couldn't the wavelengths be represented via simple FITS WCS keywords (in the SCI extension header), rather than resorting to...

Given the information provided in #6936 , which suggests that ds9 can compute it's own inverse when not provided in the header and what it computes appears to be quite...

> > Of course it also can't really hurt to have it... > > It can, if provided inverse SIP approximation is not very accurate due to how DS9 has...

Well, if we can easily provide a fairly accurate reverse solution, then I guess we're back to the state of "we might as well put it in, because it shouldn't...

@mcara can you fix the conflict in this PR, so that I can then run the regtest suite on it?