The existing colour terms reduce errors on the fixed 2,062 held cores. Turning them off while retaining the learned ePSF/WCS gives median paired OFF/ON score 1.4788; conditional95% interval 1.370–1.605.
This is an ablation, not a refitted achromatic model. Evaluation flux and nuisance scale are re-solved. Residual structure remains with colour enabled.
Full method and conclusion · Hashes and scores · Model campaign
