Linking the Short and Long delays in NGC 4151

Xray Reverberation tracks light travel delay between the continuum and thereflected iron line. Short (1e21e3 s) iron band delays have been observed inmany sources and are attributed to relativistic reverberation. The brightNGC4151 was the first to show these lags, but recent data is not consistent withsimple reverberation models. On longer time scales, the narrow Fe K line wasalso found to lag the continuum by 3 days. XMM has been instrumental in bothmeasurements. The delays at intermediate timescales (hours to 1 day) havehowever been inaccessible due to visibility constraints. Here, we propose toobserve NGC4151 for two consecutive orbits to bridge this gap. This will be asignificant step towards building a complete picture of the circumnuclear reprocessing material. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]