(for a discussion of the pulse fractional amplitudes during the 1998, 2000, 2002 and 2005 outbursts see @har08 and for the 2008 outburst see @har09). The opposite is true for the pulsed fractions of peaks: they are on average smaller than the observed fractional amplitudes during the outbursts.

Discussion {#1Hz:Discussion}
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Our analysis of the five outbursts of SAX J1808.4-3658 has shown that the fast decay, the re-flares and the 1 Hz modulation can be related phenomena in the 2002 and 2005 outbursts (and possibly in the 2000 one) which might also affect the 401 Hz pulsations. The drifts in pulse phase and the re-flares observed on time scales of days might be related with some change in the disk structure which is connected to the fast decay, which takes place on a similar time scale. The fast decay presumably is either a thermal or a viscous one, and additionally depends on the lengthscale on which significant changes occur within the disk, longer length scales corresponding to longer time scales. The 1 Hz QPO properties had previously only been very briefly discussed in the literature, and left the mechanism responsible to be identified. We therefore studied the 1 Hz modulation 