M67 membership probability as a function of position. Color indicates the individual probabilities: blue for astrometric, green for photometric, and red for joint estimation; the higher the probability, the stronger the color component(s). Colors are blended so, for example, light gray indicates uniformly high probabilities. The size of each star is proportional to the joint probability of its being a cluster star. Cluster members (stars with P> 0.5) are circled in black.