X-ray light curves of the precursor to the burst from 4U 0614+09 at 122 μs time resolution (left panels) and the burst from 2S 0918-549 at 0.25 ms resolution (right panels). The top graphs refers to photons at all photon energies, the middle ones to photons of energies below 6 keV, and the bottom ones to those above 6 keV. The X-axis refers to time since burst onset in sec. The horizontal dashed lines indicate the level of the flux at which the Eddington limit is reached in the main burst.