Flux correction factor as a function of ρ/s, the ratio between the aperture radius and the angular separation distance of the two partially overlapping comae 1 and 2, vs. different measured flux ratios of ﹩{F}_{2}^{{\prime} }/{F}_{1}^{{\prime} }﹩ (color coded as shown in the legend). The exact results and the approximate counterparts from Taylor expansion keeping the lowest order of ρ/s are plotted as solid and dotted lines, respectively. At small ρ/s, the two results are largely inseparable, thereby validating the approximation.