The distance to SS433 can be obtained directly from the radio observations.
No optical work is needed to find the parameters for the kinematic model. The
velocity and the distance
can both be derived from the radio
maps together with all the other parameters from the kinematic model.
Hjellming and Johnston (1981) noted that one can use optical observations to get more accurate measurements for some parameters.
See Appendix A for all the calculations involved for determining the
distance. Most authors find a value for the distance to SS433 of kpc.