Many RASC members are involved in the sport of occultation chasing. This activity involves monitoring a star when an asteriod is predicted to cross in front of it. By observing the dip in brightness and accurately timing it the International Occultation Timing Association (IOTA) can put together accurate estimates of the size and shape of the occulting body. This, combined with measurements of the asteroid's brightness helps to refine our knowledge of the members of the asteroid belt.
