  Reliable estimations of ephemeris errors are fundamental for the follow-up of
CoRoT candidates. An equation for the precision of minimum times, originally
developed for eclipsing binaries, has been optimized for CoRoT photometry and
been used to calculate such errors. It may indicate expected timing precisions
for transit events from CoRoT, as well as from Kepler. Prediction errors for
transit events may also be used to calculate probabilities about observing
entire or partial transits in any given span of observational coverage, leading
to an improved reliability in deductions made from follow-up observations.
