Maximum likelihood estimation of single X-ray point-source parameters in ROSAT data

The point source parameter estimation via Maximum Likelihood Estimation in ROSAT data is documented. The infall of X-ray photons is treated as a Poisson process. Based on she Poisson model, the log-likelihood function for unbinned data is derived. The adopted source and background models are explained. In the chosen parameterization, the Maximum Likelihood equations and their numerical solution are expounded. The performance of the method is illustrated by an example and tests on simulated observations.