Line profile variations due to the non-radial pulsations of HD 104237. The deviations from the mean intensity are displayed for four different nights (top left: April 22, 1999, bottom left: April 23, 1999, top right: April 24, 1999, bottom right: April 25, 1999). Dashed lines represent the limits of the equivalent profile, an additional broadening agent generates wings reaching almost  ± 2 vsini, i.e. twice the width of a pure rotational profile at continuum level.