Mass Estimation of Blackhoie Companied With a Neutron Star

A gravitational effect of binary system composed of a close neutron star and a blackhoie has been discussed in this paper. The orbit circulization caused by gravitation radiation has been Explained clearly and a time scale of the orbit circuliztion is also estimated. We have solved the vector equation of the procession in a circular orbit round a shwarchild blackhoie, and a exact solution of the equation has been obtained. Based on a relationship between the precession period and the mass of the central blackhoie, a method of estimating the mass of blackhoie companied with a neutron star is found by Us. It allows us to discuss a way of discovering blackholes. As a conclusion, we have discussed the way of discovering blackholes by means of the pulse variations of their neutron stars versus spin procession.