Distributions of the relative uncertainty – defined as the standard deviation σ divided by the mean of the measured values – for the major and minor axes of the thermal and nonthermal sources (from left to right: w_a,th, w_b,th, w_a,nth, and w_b,nth). Top row: relative statistical uncertainties given by the VFF forward fitting method. Middle row: relative systematic uncertainties derived from the four imaging methods. Bottom row: relative systematic uncertainties derived from those imaging methods that have been individually selected for each event.