A guider that causes a telescope to follow a guide star automatically by feeding control signals to the telescope's drive system. It may use a photomultiplier which views the star through the centre of a rotating mask, or a charge-coupled device (CCD) with software which monitors the position of the guide star. Some CCDs use a system known as track and accumulate in which software compensates for drift of the image when superimposing several short exposures to give the effect of one long one. The autoguider may be attached to either a guide telescope or an off-axis guider.
Subjects: Astronomy and Astrophysics.