This repo reproduced measurements of dynamical mass in two systems in the local group, Bootes 2 and Eridanus. The distance to each object is measured using the colour-magnitude diagram, fit with isochrones from Bruzual and Charlot (2003). Then, the mass is measured using spectra from the Keck and CFHT telescopes, assuming virial equlibrium, and using MCMC parameter estimation (Forman-Mackey+ 2012).