Map of the total (left) and polarised (right) radio intensity at 3 GHz (λ 10 cm) of NGC 628 overlaid on an Hα and XMM-Newton Optical Monitor in UVW1 filter map, respectively. The contour levels are 3, 5, 8, 16, 32, 64, 128, 256, and 512 × 24 μJy (left) or 10 μJy (right). The lines show the orientation of the magnetic fields, and their lengths of 1′ are proportional to the polarised intensity of 150 μJy (left) or to a degree of polarisation of 36% (right). The angular resolution is 30″.