Response of an extended parsec-scale structure with inner radius of R_in = 0.01 pc line response and outer radius R_out = 10 pc. The dashed lines correspond to the upper and lower errors of R_out. Inset: Reduced-χ² from the Fe Kα light-curve fit best estimate of the external radius. The blue marker and red dashed line represent the best-fitting value, and the error bar corresponds to Δχ² = 5.