Timing reactions

Application for Determining Reaction Time (Personal Equation)

When a minor planet (asteroid, planetoid) passes in front of a star, the star will be occulted for a short while, typically for a few seconds. Exact measurements from various places make it possible to determine the asteroid’s size and shape. Such occultations can often be observed with small instruments, e.g. binoculars. The predicted times frequently differ from the real ones. The event can sometimes come unexpectedly, making it difficult to obtain the correct time.

You can download a piece of software to test your own reaction times from this external website.

If you require specific occultation data for your locality, or details of occultations involving fainter stars, please get in touch with the Director of the Occultation Section giving your geographical location. Graphical representations of each occultation will be available at the Occultation Sections web-site before the event is due to take place.