Bayesian Analysis of Stellar Evolution is an international collaboration studying stellar evolution with an emphasis on stellar ages. We also develop and support a Bayesian software suite that recovers star cluster and stellar parameters from photometry, currently called BASE-9.

BASE-9 is useful for analyzing single-age, single-metallicity star clusters, binaries, or single stars, and for simulating such systems. BASE9 uses Markov chain Monte Carlo to estimate the posterior probability distribution for the age, metallicity, distance modulus, and line-of-sight absorption for a cluster, and for the mass, binary mass ratio, and cluster membership probability for every cluster member.