Performances of optimal pseudofilter, Gaussian filter, and Mexican hat wavelet. In the top panel a portion of a 32,768 pixel one‐dimensional simulation is shown. In the simulation there are present Gaussian sources of width ﹩\theta =3\theta _{p}﹩ and ﹩1/ f﹩ noise. The amplitude of the sources is 1 for all of them. The dispersion of the background is set to be ﹩\frac{1}{3}﹩. The second (third) panel from the top shows the map after filtering with the optimal pseudofilter (a Gaussian of width θ). The bottom panel shows the map after filtering with a Mexican hat of width θ. The positions of the sources are marked with asterisks. In the three cases the 3 σ level of the resultant map is shown with an horizontal dotted line.