9 - Precision Tracking and Guiding

Summary

No telescope mount tracks the stars perfectly, but some do better than others. Astrophotography at long focal lengths almost always requires guiding corrections. In the past this meant the astrophotographer had to watch a star continuously and press buttons to keep it centered on the crosshairs. This was an agonizing process when film exposures typically lasted an hour. Nowadays we use autoguiders, which watch the star automatically, or else, increasingly, we make exposures short enough, and tune our mounts carefully enough, that no corrections are needed. This is presently an area of rapid technical progress.