LUCKY SIGHTINGS AND PREDICTIONS
Satellite observing can be enjoyed on many levels. Most skywatchers simply enjoy keeping an eye out for satellites while they are doing other kinds of observing. For this, all you need is a lucky glance in the right direction at the right time. Satellites can even be rather intrusive, leaving their trails on long-exposure astrophotographs, or startling deep-sky observers by racing through their field of view.
Interested observers can obtain predictions for when artificial satellites will appear in their area. Favorite targets include the space station Mir, the space shuttle, and the Hubble Space Telescope. Predictions are supplied by groups such as the Belgian Working Group Satellites, or via web sites such as the Visual Satellite Observer's Home Page.
A few dedicated amateurs obtain software packages that enable them to make their own satellite predictions, and then diligently monitor satellite appearances, positions, and brightnesses. These observations can help scientists to accurately track satellite orbits and study how they are affected by changing conditions in the atmosphere and fluctuations in Earth's gravitational field.
To determine a satellite's position, you note exactly when and where the satellite crosses an imaginary line between two stars that are close to each other in the sky. This can be done by eye, but if you wish to submit your records, you will need to use a telescope or take photographs. For more information on contributing positional measurements of satellites, contact the Royal Greenwich Observatory, Satellite Laser Ranging Team.