Distribution of the thermal radio emission from M 101 at λ 6.2 cm overlaid on a greyscale plot of the Hα emission of Hoopes et al. (2001) smoothed to the same beamwidth of (shown in the lower left corner). Contour levels are (1, 2, 3, 4, 6, 8, and 12)  × 1.5  mJy/beam area . The noise level is about 0.5  mJy/beam area . The white plus shows the position of the optical centre. The strong source near the eastern border of the map is the H ii -region complex NGC 5471.