Prepare for moving construct_wcs_corrector out to pipelines

[mcara]

This PR is the first step of moving construct_wcs_corrector to pipelines. This is the approach that I favor for fixing #528 in conjunction with a new release (0.9.0) of tweakwcs after spacetelescope/tweakwcs#243 is merged.

Associated Prs:
spacetelescope/romancal#2219
spacetelescope/jwst#10306

Tasks

• update or add relevant tests
• update relevant docstrings and / or docs/ page
• Does this PR change any API used downstream? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see changelog readme for instructions)
  • if your change breaks existing functionality, also add a changes/<PR#>.breaking.rst news fragment
• run regression tests with this branch installed ("git+https://github.com/<fork>/stcal@<branch>")
  • jwst regression test
  • romancal regression test

[mcara]

Regression test for JWST: https://github.com/spacetelescope/RegressionTests/actions/runs/22769717421
Romancal should pass if JWST passes - the changes are minor and affect both pipelines in the same way.

[braingram]

Regression test for JWST: https://github.com/spacetelescope/RegressionTests/actions/runs/22769717421 Romancal should pass if JWST passes - the changes are minor and affect both pipelines in the same way.

This will also need a passing romancal regtest run.

Would you help me understand how this relates to #528 or spacetelescope/tweakwcs#243

What is the plan here? Is this PR ready independent of spacetelescope/tweakwcs#243?

[mcara]

What is the plan here? Is this PR ready independent of spacetelescope/tweakwcs#243?

Yes, it is independent, but the two follow-up PRs will depend on tweakwcs release.

[mcara]

Romancal tests: https://github.com/spacetelescope/RegressionTests/actions/runs/22771003096

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.80%. Comparing base (6ae62a7) to head (7e95209).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #529   +/-   ##
=======================================
  Coverage   91.79%   91.80%           
=======================================
  Files          63       63           
  Lines        8858     8855    -3     
=======================================
- Hits         8131     8129    -2     
+ Misses        727      726    -1     

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[mcara]

My previous tests were set-up incorrectly. Starting new tests:

• JWST: https://github.com/spacetelescope/RegressionTests/actions/runs/22772788548
• Romancal: https://github.com/spacetelescope/RegressionTests/actions/runs/22772858867

[braingram]

Would it be easier (and equivalent) to just replace:

stcal/src/stcal/tweakreg/tweakreg.py

Lines 352 to 353 in 0e218f9

	original_skycoord = corrector.meta["original_skycoord"]
	separation = original_skycoord.separation(aligned_skycoord)

with:

 original_skycoord = _wcs_to_skycoord(corrector.original_wcs)
 separation = original_skycoord.separation(aligned_skycoord) 

and drop the handling of meta["original_skycoord"].

[mcara]

Would it be easier (and equivalent) to just replace:

stcal/src/stcal/tweakreg/tweakreg.py

Lines 352 to 353 in 0e218f9

	original_skycoord = corrector.meta["original_skycoord"]
	separation = original_skycoord.separation(aligned_skycoord)

with:

 original_skycoord = _wcs_to_skycoord(corrector.original_wcs)
 separation = original_skycoord.separation(aligned_skycoord) 

and drop the handling of meta["original_skycoord"].

This is an excellent observation! I see no reason not to do this. Initially I wanted to eliminate WCS copying for performance reasons but I kept original_wcs and made a copy of it to be modified. The alternative is to drop deepcopying "original wcs" at cost of correctors having side-effects like modifying input arguments which I do not like.

[mcara]

One side-effect of #529 (comment) is that now downstream tests fail because this is a breaking change (well, affecting only unit tests - not the actual code).

[braingram]

One side-effect of #529 (comment) is that now downstream tests fail because this is a breaking change (well, affecting only unit tests - not the actual code).

Thanks. The failing jwst test looks like it's just testing the private stcal method _is_wcs_correction_small. I propose that we delete that test in jwst. Would you open a PR removing the test? One the test is removed the tests should pass with this PR and it can be approved and merged.

[mcara]

yes, I'll do that

[mcara]

@braingram Done in spacetelescope/jwst#10354

[PaulHuwe]

LGTM

[tapastro]

JWST has a build release this week - is it okay if we wait to merge this until after the release? I'm hoping to avoid any possible complications.