  The fine precision of photometric data available from missions like Kepler
provide researchers with the ability to measure changes in light on the order
of tens of parts per million (ppm). This level of precision allows researchers
to measure the loss of light due to exoplanet transits as well as the light
emitted by an exoplanet, or planetary photometric emissions. The planetary
photometric emissions are due to the thermal emissions of the exoplanet, and
reflected stellar light. In many cases it is assumed that the incident stellar
light may be modeled as plane parallel rays. For extremely close-in exoplanets
the finite angular size of the host star must be taken into account and the
plane parallel ray model breaks down. One consequence of modeling the incident
stellar radiation in this manner is the creation of three distinct zones as
opposed to the two zones present in the plane parallel ray model. The three
zones are the fully illuminated, penumbral, and un-illuminated zones. The
existence of the penumbral zone means that more than half of the exoplanet will
be at least partially illuminated by the host star. In this work we will
present a complete derivation of the reflective luminosity of the fully
illuminated zone. In addition, we will present an outline for the derivation of
the reflected intensity distribution of the penumbral zone. Within this work we
will also derive a new expression for the thermal luminosity of an exoplanet by
treating each of the three zones as a blackbody emitting at a constant
temperature. Finally, it will be shown that an estimation of the radius of the
exoplanet requires proper accounting of light from the penumbral zone during
the primary transit. Not doing so risks underestimating the radius of the
exoplanet and an overestimation of its geometric albedo and nightside
temperature.
