KEPLER_RMAX

          Outer radius for the Radius-Velocity diagram (in au).
      KEPLER_RMAX must be greater then KEPLER_ROUT.

      KEPLER_RMAX is an optional variable. By default (i.e.
      if the variable has not been created by the user),
      the maximum radius is taken as KEPLER_ROUT + 5*KEPLER_STEP.