The light curve from an asteroidal occultation is affected by the size of the asteroid, Fresnel diffraction of light around the edge of the asteroid, and the effects of the star having a significant diameter, all of which is affected by noise from the earth's atmosphere and from the detector. This sessions will provide a an overview of these issues, followed by a demonstration of AOTA - Asteroidal Occultation Time Analyser - a tool for analysing an asteroidal occultation light curve.