Terminating Messier 4

We have obtained deep HST imaging (to V=30, I=28) in Messier 4, and have constructed proper-motion cleaned colour-magnitude diagrams that contain several groups of objects whose properties can only be revealed with deep NIR photometry. We propose to obtain deep J,K Flamingos-I images of our HST field that will help us understand the location of the hydrogen-burning limit in metal-poor stars, improve the theoretical models of metal-poor stars and provide a solution to the origin and properties of a mysterious red population of faint stars near the Galactic centre.