086168

X-ray Reverberation tracks light travel delay between the continuum and the reflected iron line. Short openPar1e2-1e3 sclosePar iron band delays have been observed in many sources and are attributed to relativistic reverberation. The bright NGC4151 was the first to show these lags comma but recent data is not consistent with simple reverberation models. On longer time scales comma the narrow Fe K line was also found to lag the continuum by 3 days. XMM has been instrumental in both measurements. The delays at intermediate timescales openParhours to 1 dayclosePar have however been inaccessible due to visibility constraints. Here comma we propose to observe NGC4151 for two consecutive orbits to bridge this gap. This will be a significant step towards building a complete picture of the circumnuclear reprocessing material.