Top panel: the final map of AQ And at 70 μm when the central star and shell are not masked during median filtering with a “high pass filter width” of 20. The “shadowing effect” is clearly visible. The central star does not look round but that is due to the secondary mirror support structure which introduces a tri-lobe shape of the PSF at a low flux level. Lower panel: the map when the central star and shell are masked and a high pass filter width of 35 is used.