A device that allows a telescope to follow a guide star during photography or imaging. Guiding is necessary to compensate for small mechanical errors in the telescope and mounting, and changes in atmospheric refraction. There should be a means of monitoring a guide star and making small corrections to either the telescope's movement or the position of the camera. The monitoring may be carried out using a guide telescope or an off-axis guider, either visually or with an autoguider.
Subjects: Astronomy and Astrophysics.