Observations of the Be star f Car. Panels from top to bottom: TESS light curve (black), Hα EW, dynamical spectrum of Hα emission (after subtracting the photospheric profile), EW_V/EW_R of Hα, V/R and then peak separation (PS) of Hα emission (with the photospheric profile subtracted). The start of two outburst events are indicated by vertical shaded rectangles. The red curve in the top panel traces the low-frequency signals (below 0.5 d⁻¹). The solid green curve in second and sixth panels are Gaussian Process Regression fits to (sections of) the measurements. The fit of Eq. (2) is plotted for the first few days of the two flickers for EW_V/EW_R and V/R, with the corresponding frequencies indicated. The two downward arrows near TJD 3013 are the two epochs emphasized in Fig. 2.