and
      converged light time solutions is recommended when adequacy of
      the one-iteration solution is in doubt.


      Converged corrections
      ---------------------

      When the requested aberration correction is 'CN', 'CN+S',
      'XCN', or 'XCN+S', as many iterations as are required for
      convergence are performed in the computation of LT. Usually
      the solution is found after three iterations. The relative
      error present in this case is at most

          (V/C)**4
         --