Measured ξ for the highly ionized outflowing absorber in the 2009 Long Look spectra, with different Γ_ion used as input in the Xstar simulations; error bars are purely statistical errors at 1σ confidence level. The vertical dotted line marks the best-fit measured Γ for the 2009 Long Look spectra, along with its statistical (dashed lines) and systematic (continuous line) errors that have been estimated considering the uncertainties of the power-law normalization and of the ionized absorbers.