sampling in catalog space

The only small bit of research I got done today was writing some text for Brewer's masterpiece on sampling in catalog space. Given an image of the sky, he can sample the posterior PDF over catalogs, along with the posterior PDF for hyperpriors on the number–flux relation of stars. By using nested sampling he doesn't get killed by the combinatoric degeneracies that arise from the catalog re-ordering degeneracy. Even better, he models the stars that are too faint to cleanly detect. Even better, the different catalogs in the sampling have different numbers of entries; that is, this is sampling at variable model complexity. Congratulations Brewer!

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