WISE band-4 images for the genuine Algol CZ Vel (left) and the Be star SX Aur (right). The images are centred on the objects, with north up and east to the left. The flux scale goes from the background level to background plus 150 times the background scatter σ, and the first thin (green) contour line corresponds to the background level plus 3 times its fluctuation, the next intermediate (blue) contour curve to 5σ, and the inermost thick black contour line to 10σ.