WEXTER and ERAFITTER: two programs to fit MW at LEP2 using the best measurable kinematical variables

In this paper, we present two programs to fit MW at LEP2 using the best measurable kinematical variables. The theoretical probabilities of observing the final-state kinematical configurations are computed by integrating over the quantitites that are not well measured. Therefore, an event-by-event kinematical reconstruction is avoided. MW is then determined through a maximum likelihood fit.