Comparison of the S/Ns (median of each sample in each pixel) of the continuous BP/RP spectra of a sample of 1 000 RR Lyrae stars with 14 < ⟨G⟩< 16 mag extracted from the vari_rrlyrae table (red line) and the continuous BP/RP spectra of a control sample composed by 1 000 random non-variable sources with 14 < G < 16 mag. The random sources (black line) have a much higher pixel-wise S/N than the RR Lyrae stars (red line), even though both samples are drawn from the same apparent G range.