NICER observation list: Target ID 263301

We propose a monitoring program of NGC 4151 to track the coronal temperature variations as the source flux changes, and at the same time track how the narrow Fe K line and the Compton hump respond to those flux changes. The pair-dominated model for the corona has a testable prediction for the dependence of cutoff energy on flux and spectral index, while a Compton-thick hypothesis for the narrow Fe Line predicts a correlation between the line flux, the Compton hump and the continuum flux. We will test these predictions and advance our understanding of the corona and the reflector producing the strong Fe K line.