Following DM-33279, we can write a task that re-estimates the PSF model using uniquely/consistently reserved stars.

Discussion with Jim Bosch has led to the following plan:

• This will be run after fgcmcal/jointcal (but at the moment it will not use these outputs as inputs)
• This will be run before skycorr
• This is run per-ccd at the moment.
  The inputs will be:
• calexp (to measure the psf)
• src catalog which a subset will be input to psf estimator task
• tract-by-tract isolated stars
  In the task it will:
• Read src, apply a schema mapper to cut down to relevant columns.
• Run psf estimator (excluding reserved stars)
• On the psf stars (+ reserve stars) run each algorithm that requires an aperture correction
• Compute aperture correction for each algorithm
  The outputs will be:
• The psf model (in its own file)
• The apcorr model (in its own file)
• The psf catalog (source catalog with measurements + flags including psf_used and psf_reserved).

The coadd make warp code will have to be updated to know to use these psfs, aperture corrections, and psf catalog (for flags).