  The ability to observe extrasolar planets transiting their stars has
profoundly changed our understanding of these planetary systems. However, these
measurements depend on how well we understand the properties of the host star,
such as radius, luminosity and limb darkening. Traditionally, limb darkening is
treated as a parameterization in the analysis, but these simple
parameterizations are not accurate representations of actual center-to-limb
intensity variations (CLIV) to the precision needed for interpreting these
transit observations. This effect leads to systematic errors for the measured
planetary radii and corresponding measured spectral features. We compute
synthetic planetary transits using model stellar atmosphere CLIV and
corresponding best-fit limb-darkening laws for a grid spherically symmetric
model stellar atmospheres. From these light curves we measure the differences
in flux as a function of the star's effective temperature, gravity, mass, and
the inclination of the planet's orbit.
