Accuracy of AP estimation with the GSP-Phot algorithm Aeneas using BP/RP spectra of stars at G = 15 covering the full AP space shown. There are a total of 2000 stars in this test sample. The vertical structure of points visible in the bottom panels is due to our procedure to generate test spectra from a limited supply of synthetic spectra. This causes spectra of identical AP values to appear multiple times in the test set, though these spectra differ in their noise realizations.