Map of the normalised spatial gradient of linearly polarized emission, |∇P|/|P|, in Aitoff projection of the entire southern sky at a reference frequency of 2.3 GHz and a resolution of 11′. The noise level in the map was obtained by averaging intensity over a small region with no signal and intensity is clipped at 3σ. The scaling runs from 0.2 (black) to 1000 (white). Intensity unit is beam^-0.5.