0120114

We propose observations of 2 brightest Seyfert 1s NGC 4151 and IC 4329A with exposure of 7.5E5 s each. The main goal of the observations is to accurately measure the shape of their high-energy >100 keV spectra. This will allow us to determine the relative contribution of thermal and non-thermal Comptonization in the sources. The presence of non-thermal Comptonization will lead to power-law like tails as well as broad pair annihilation features beyond the thermal cutoff. Such measurements will have profound theoretical consequences. Furthermore we will study short-time scale variability of the sources and correlations between various spectral components. This will further constrain the physical processes and geometry of the sources. The field of view of IC 4329A also contains the famous MCG-6-30-15 which spectrum we will measure as well. For all observations we will apply for XMM time to provide simultaneous detailed measurements of the Fe K line and edge complex. [truncated! Please see actual data for full text]