Autoguida

Autoguida, in astronomy, refers to an automated system used to keep a telescope precisely pointed at a target during long-exposure imaging. It works by monitoring a guide star with a small guide camera and using a real-time feedback loop to send corrections to the telescope mount. The goal is to compensate for tracking errors caused by mechanical flexure, imperfect polar alignment, and atmospheric disturbances, thereby reducing star trailing in long exposures.

A guiding setup can use either a separate guide scope or an off-axis guider. The guide camera captures short exposure images of a guide star, and software determines the star’s centroid relative to a reference position. If the star drifts, the system issues corrective commands to the mount on the right ascension and declination axes. Exposures for guiding are typically short, from a fraction of a second to a few seconds. Guiding software such as PHD2 is widely used, often in conjunction with drivers and interfaces provided by mount manufacturers via ASCOM or INDI.

Autoguiding is essential for many amateur and semi-professional astrophotography workflows, enabling longer total integration times and higher image quality for deep-sky objects. It interfaces with common imaging equipment, including CCD or CMOS cameras and computerized mounts. The technique has evolved from dedicated, standalone devices to software-driven solutions that integrate with modern telescope control systems, expanding accessibility for enthusiasts and researchers alike.

Limitations include the need for a suitable guide star, sufficient mount performance, and stable observing conditions. Autoguiding does not correct all error sources, but it significantly reduces drift and improves tracking for long exposures.