  From simulations of transit observations, it is found that the detectability
of extrasolar planets depends only on two parameters: The signal-to-noise ratio
during a transit, and the number of data points observed during transits. All
other physical parameters describing transit configurations (planet and star
size, orbital period, orbital half axis, latitude of the transit across star)
can be reduced to these two parameters. In turn, once the dependency between
transit detectability and these two parameters has been determined, predictions
for an instrument's ability to detect transits by any combination of physical
parameters can be derived with ease. These predictions are applied to the
Eddington proposal of a combined Astroseismology/Transit-detection space
mission currently under study by ESA, which is described briefly.
