This paper describes a path toward the development of theory for using a photon counting camera as a star tracker for spacecraft attitude estimation. The benefit of using a photon counting camera is that star data can be sampled at a faster rate while allowing one to measure very dim stars, increasing the number of stars available for attitude estimation. The development of a noise model is discussed and an algorithm to process raw data is shown. An attitude estimation method is discussed and simulated data is shown. A simulated star tracker for attitude estimation is shown and attitude estimation results are shown.