Skip to content

Account for changes to PC and CD matrix when unwrapping to a FITS WCS that has been rebinned. #862

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 2 commits into
base: main
Choose a base branch
from
Draft

Account for changes to PC and CD matrix when unwrapping to a FITS WCS that has been rebinned. #862

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
ced7729
adjust PC and CD matrix when rebinning
wtbarnes Jun 23, 2025
1363d8c
Merge branch 'main' into rebin-respect-cd-matrix
wtbarnes Sep 10, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 10 additions & 1 deletion ndcube/wcs/tools.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ def unwrap_wcs_to_fitswcs(wcs):
offset[kept_wcs_axes] = low_level_wrapper._offset
fitswcs = _resample_fitswcs(fitswcs, factor, offset)
else:
raise TypeError("Unrecognized/unsupported WCS Wrapper type: {type(low_level_wrapper)}")
raise TypeError(f"Unrecognized/unsupported WCS Wrapper type: {type(low_level_wrapper)}")
return fitswcs, dropped_data_axes


Expand Down Expand Up @@ -185,4 +185,13 @@ def _resample_fitswcs(fitswcs, factor, offset=0):
fitswcs.wcs.cdelt *= factor
fitswcs.wcs.crpix = (fitswcs.wcs.crpix + offset) / factor
fitswcs._naxis = list(np.round(np.array(fitswcs._naxis) / factor).astype(int))
# TODO: Add some context about why this correction is made
if hasattr(fitswcs.wcs, 'pc'):
scaling_matrix = np.eye(fitswcs.wcs.naxis)
for i in range(fitswcs.wcs.naxis):
for j in range(fitswcs.wcs.naxis):
scaling_matrix[i,j] = factor[j] / factor[i]
fitswcs.wcs.pc *= scaling_matrix
if hasattr(fitswcs.wcs, 'cd'):
fitswcs.wcs.cd *= factor
return fitswcs
Loading