Comparison between the amplitude spectrum of HS 2324 in 1997 (Silvotti et al. 1999) and 2019 (TESS data). The detection threshold (dash-dotted magenta line) in 2019 is slightly higher (2.07 ppt with sector 16 and 17 together vs. 1.62 ppt in 1997), but the spectral window (red, upper right panels) is much cleaner. This partially explains the higher density of the peaks in 1997. The low level of noise below ∼100 μHz in 1997 is due to artificial filtering.