a) Normalized diffracted stellar flux Φ (see scale on the left) caused by a moonlet of radius r_m = 0.3 km, as a function of the distance l travelled in the plane of the sky, at a resolution of 0.02 km. We assume here a zero miss-distance (diametric occultation) and a Fresnel scale of F_S = 2 km, relevant to NACO observations. The vertical solid lines define the central Fresnel region of radius , where Φ varies slowly. The vertical dotted lines define the Airy region of radius where the rapidly oscillating ripples have the largest amplitudes. b) Equivalent width E_m calculated over a 6 km-wide running box. For a box centered at l = 0 km, E_m slightly exceeds the value 0.15 km corresponding to the 3σ limit provided by the NACO observation (shaded rectangle). c) Same as curve a), but with a shadow miss distance of 7.6 km. d) Same as b), but corresponding to the light curve c).