Merge pull request #64 from PhangsTeam/cross-corr-get-wcs-adjust

Add cross-correlation to get_wcs_adjust_step.py

CHANGES.rst

@@ -1,6 +1,9 @@
 1.1.1 (Unreleased)
 ==================
 
+- Fix bug in ``astrometric_align_step`` if first pass of alignment succeeds but second
+  fails
+- Add cross-correlation option to ``get_wcs_adjust_step``, which uses ``spacepylot``
 - Add control over reproject functions, can be ``reproject_interp`` (default), ``reproject_exact``,
   or ``reproject_adaptive``. For MIRI, ``reproject_exact`` may work better. This applies to ``anchoring_step``,
   ``astrometric_align_step``, ``level_match_step``, ``multi_tile_destripe_step``, ``psf_matching_step``, and

config/3707/config.toml

@@ -91,6 +91,9 @@ jwst_parameters.bkg_subtract.sigma = 1.5
 
 [parameters.get_wcs_adjust]
 
+method.nircam = "tweakreg"
+method.miri = "cross_corr"
+
 bands = [
     'F300M',
     'F770W',

docs/steps/get_wcs_adjust.rst

@@ -8,6 +8,9 @@ shift per-visit (since JWST cycles between filters), and apply that shift to all
 that taking a long NIRCam band that is ideally stellar dominated (i.e. F300M) works best for NIRCam, and a shorter
 wavelength, non-PAH-dominated MIRI band (i.e. F1000W) is ideal for MIRI.
 
+By default, this step uses tweakreg, but can also be swapped out for cross-correlation via optical flow. This may be
+more optimal if you don't have any point source dominated wavebands, such as if you only have F770W, for instance.
+
 ---
 API
 ---

pjpipe/astrometric_align/astrometric_align_step.py

@@ -676,6 +676,12 @@ def tweakreg_align(
                 except ValueError:
                     log.warning("No catalog matches found. Defaulting to no shift")
 
+                    # Reset everything to avoid crashes
+                    wcs_aligned_fit = None
+                    xoffset, yoffset = 0, 0
+                    shift = np.array([0, 0])
+                    matrix = np.array([[1, 0], [0, 1]])
+
             target_wcs_corrected = copy.deepcopy(target_wcs_corrector_orig)
 
             # Put the correction in and properly update header.