R       =  8.3 kpc

       v(esc)  =  528 km/s


    Q:  What is the mass interior to this radius?


           The equation relating the quantities is slightly different
           than that for objects in circular orbits; note the factor
           of 2.

                                v(esc)^2 * R
             M(interior)  =   ---------------------
                                  2 * G


                          =   5.3 x 10^(41) kg

                          =   2.7 x 10^(11) solar masses