Contour image of M 81^∗ obtained by hybrid mapping on the self-calibrated data set. Contours are logarithmic, separated by a factor , with the lowest level set at 1.8 mJy/beam, that is, three times the root-mean-square noise of the image. The peak of brightness is 112 mJy/beam. The interferometric beam, shown in the bottom left corner has a size of 0.361  ×  0.168 mas and a position angle  − 1.6°.