Intensity variations at the footpoint of a large loop which supports a transverse oscillation, taken from TRACE observation on September 15 2001. Top: relative intensity of the TRACE 2d loop region, averaged over the longitudinal coordinate from the foot point up to 22 Mm, as a function of time and transverse distance. The vertical dashed line indicates the reference time t₀. Middle: intensity of the same region, averaged over transverse distance, as a function of time. The dashed line is a smooth trend that is taken to be the background intensity. Bottom: relative intensity fitted with a damped oscillator between times t₀ and t₁, is shown as a dashed curve. Reproduced from Verwichte et al. (2010).