Second, in [SAX J1808]{}the dip appears related to the pause during the rise. If this relation is real, then whatever physical mechanism underpins these features may also be related to the rebrightening.

Burst Oscillations {#burst-oscillations}
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We found that the X-ray burst shows burst oscillations at the expected 401 Hz spin frequency. Comparing these oscillations with the accretion-powered pulsations, we find that the two waveforms are remarkably similar, but the burst oscillations lead the pulsations by [$34\arcdeg\pm7\arcdeg$]{}. Similar results were reported from [*RXTE*]{}observations of burst oscillations in [SAX J1808]{}observed during the cooling phase of an X-ray burst [@Chakrabarty2003]. The fact that the burst oscillations are so closely matched to the persistent pulsations in terms of their waveform, suggests that both must arise from geometrically similar, if not the same, confined emitting region (hot-spot) on the stellar surface. With this in mind, it is interesting to note that the [*NICER*]{}data indicate the waveform energy dependence of the burst oscillations is quite different from that of the persistent pulsations. Some of the difference may simply arise from the strong reflection component, which is likely not pulsed, and thus is expected to dilute the measured burst oscillation amplitude at low energies. A detailed 