Left panel: contour plot of the deconvolved 70 μm PACS image of W Aql. Two Archimedean spirals matching the outline of the IR emission are recognizable. The (black) dotted spiral has one winding to cover the emission with a separation distance θ = 52″ while the (white) dashed spiral has two windings with a separation distance θ = 26″. Right panel: the same image overplotted with an ellipse fitted to the IR emission. The axes lengths of the ellipse are 69″ and 59″, respectively, with the major axis oriented along PA = 35°.