The MC (Markovian chain) flux of events is a mathematical model of the fluxes of elementary particles (photons, electrons, etc.). To estimate its state, we have derived a recursion formula for the a posteriori probability that is most comprehensive characteristic of the state of an event flux. The decision on the flux state is made using a criterion of the a posteriori probability maximum. We present here some results of calculations of the a posteriori probability along with the results of statistical experiment using an imitation model