SOM-based tomographic bin definition + n(z) #274

Define tomographic bins and n(z) via a SOM. Owner: Klara.

Plan (from the Bochum telecon with Angus Wright, 21 Sep; 22 Sep call notes): follow KiDS-Legacy. One SOM (one magnitude + four colours) trained on UNIONS photometry in W3, with the spectroscopic samples there. Gold weighting rather than a gold cut. Constant-shear image sims. Clustering redshifts (DESI overlap) cross-check the mean. The two UNIONS z filters are mapped onto one system. If W3 turns out unrepresentative of the survey, fall back to two SOMs with a transfer function (DES Y6). Pipeline: CosmoPipe. Next: a first n(z) on current data.

Open: equipopulated vs a-priori bin boundaries.

Context: Paris meeting notes