Radial surface brightness profile of the radio halo in A773. Left: data points represents the averaged surface brightness measured in the magenta annuli shown in the right panel. The red curve is the theoretical exponential profile and the black curve is the profile convolved with the beam of the image. Right: radio image of A773 (see Table B.1). Contours start at 3-σ rms noise and are spaced by a factor of two. The orange circle in the bottom left corner shows the size of the beam.