The WFIRST coronagraph, currently in the design phase, will make possible for the first time the direct imaging of exoplanets down to Jupiters. The main technical challenge in direct detection comes from three areas: starlight suppression, low flux detection, and speckle stabilization in the dark zone where the planet or disk light is to be detected. These three aspects in turn place requirements on key instrument parameters such as system throughput, raw contrast and detector effects. The link between instrument limitations and instrument performance is captured in models, and balanced using error budgets. Instrument performance can be measured in terms of the science yield, which is itself limited by available mission time and the instrument sensitivity floor. In this paper, we present an overview of the modeling and methodology to assess the sensitivity of the coronagraph and some of the key results pertaining to the WFIRST coronagraph.
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