You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
Implement fourth-order moments for PSF diagnostics (PSFHOME-style; useful for PSF-leakage systematics in DES/HSC).
Current state. No higher-order-moment code exists on develop. PR #698 (branch moment4) implemented this in psfex_interp.py (_get_psfshapes / _get_starshapes): whiten the pixel grid with the inverse-sqrt second-moment matrix, compute the centered p+q=4 moments, store the spin-2 combinations M40 − M04 and 2(M13 + M31) as M_4_{PSF,STAR}_{1,2}. That branch is now ~435 commits behind develop and predates the HSM column-grammar refactor.
Plan. Implement as a follow-up on top of #812 (sky-coords HSM), which rewrites the same two functions. Measuring in sky coordinates removes the pixel→sky rotation the old code would need. Deliverables:
spin-2 fourth-moment combinations (port the fourth-order moments #698 math onto the sky-coords frame; the whitening matrix must be built from the sky-frame moments),
galsim's spin-0 moments_rho4 (already computed by FindAdaptiveMom, currently discarded),
tests for both.
#698 is kept open as reference for the original implementation; the new work supersedes it.
Implement fourth-order moments for PSF diagnostics (PSFHOME-style; useful for PSF-leakage systematics in DES/HSC).
Current state. No higher-order-moment code exists on
develop. PR #698 (branchmoment4) implemented this inpsfex_interp.py(_get_psfshapes/_get_starshapes): whiten the pixel grid with the inverse-sqrt second-moment matrix, compute the centered p+q=4 moments, store the spin-2 combinationsM40 − M04and2(M13 + M31)asM_4_{PSF,STAR}_{1,2}. That branch is now ~435 commits behinddevelopand predates the HSM column-grammar refactor.Plan. Implement as a follow-up on top of #812 (sky-coords HSM), which rewrites the same two functions. Measuring in sky coordinates removes the pixel→sky rotation the old code would need. Deliverables:
moments_rho4(already computed byFindAdaptiveMom, currently discarded),#698 is kept open as reference for the original implementation; the new work supersedes it.