  BASE-9 is a Bayesian software suite that recovers star cluster and stellar
parameters from photometry. BASE-9 is useful for analyzing single-age,
single-metallicity star clusters, binaries, or single stars, and for simulating
such systems. BASE-9 uses Markov chain Monte Carlo and brute-force numerical
integration techniques to estimate the posterior probability distributions for
the age, metallicity, helium abundance, distance modulus, and line-of-sight
absorption for a cluster, and the mass, binary mass ratio, and cluster
membership probability for every stellar object. BASE-9 is provided as open
source code on a version-controlled web server. The executables are also
available as Amazon Elastic Compute Cloud images. This manual provides
potential users with an overview of BASE-9, including instructions for
installation and use.
