Cumulative flux of the Crab nebula (top panel) obtained at 150 GHz over 5′ from the centre obtained by aperture photometry. The flux has been corrected by a zero level in the map, which corresponds to the mean of the signal calculated in an annular ring, as indicated by the white circles on the map and by the blue dotted lines on the top. The green dotted line represents the uncertainties measured at large radii.