The SDSS catalogues used. We show a six-degree thick slice drawn from the catalogues used in our analysis. The red points are the LRG galaxies, which form a nearly volume-limited sample at z > 0.15. The “main” galaxies of the SDSS are depicted in blue. As shown, we use the “main” galaxies from z > 0.09, and we use only the LRG in an inner volume, allowing for a buffer region of r_buff = 175   h^-1   Mpc from any of the borders of the “main” sample volume. For our analysis, we use the samples covering a total area of 5511deg². The radius of a typical BAO shell is shown as a segment. At the top insets, we show two orthogonal slices of width 20   h^-1   Mpc, centred on a particular LRG. The BAOlet coefficient map W_R,s(x) has a large value at the position of this centre (for R_max,s_max), thus we expect to find a strong BAO signal. The two circles have the radii of 100 and 110 h^-1   Mpc, respectively. This is a single BAO shell where the over-density can be appreciated by eye on the right scale.