Example estimation of the AC FWHM as a function of AC rate, for one particular FOV (FOV1) and CCD (ROW3 AF5). The upper and lower panels correspond to ungated 2D observations in the AC rate ranges 0.175-0.200 and 0.6000.625 pix s⁻¹, respectively. The grey points are samples from the marginalised and normalised AC LSFs of a large number of observations, aligned according to the AC location of the source. The black curve is a polynomial fit to the samples, with the vertical lines indicating the maximum and half-maximum locations from which the AC FWHM (quoted in the figures) is derived.