Tyler McCracken, doctoral candidate in the Physics Department, will defend his dissertation, "Closing the Loop on the MRO Interferometer ICoNN Tracker." The heart of the Magdalena Ridge Observatory Interferometer (MROI) is the fringe tracker, or ICoNN, which is the instrument that pushes the interferometer’s limiting magnitude beyond the current state-of-the-art. For ground-based interferometers to continuously observe high contrast fringes, and be able to reliably form images, the effects of the turbulent atmosphere must be kept under control. The fringe tracker tracks the random, constantly-changing, path length variations between combination partners, keeping the entire interferometer in phase. McCracken will present the process in which the loop was closed on the ICoNN (Infrared Coherencing Nearest Neighbor) tracker, demonstrating its capability to track atmospheric-like perturbations.