Definition
An altazimuth mount is a two‑axis mechanical support that allows an instrument—most commonly an optical telescope, camera, or antenna—to be positioned by rotating it around a vertical axis (azimuth) and a horizontal axis (altitude, also called elevation).
Overview
Altazimuth mounts are widely used in amateur and professional astronomy, as well as in satellite communication and radio telescopes. Their simplicity and stability make them attractive for portable equipment and large observatories alike. Unlike equatorial mounts, which are aligned with Earth’s rotational axis, altazimuth mounts track celestial objects by moving simultaneously in both axes, requiring computer control for long exposures in astrophotography.
Etymology / Origin
The term combines the Latin words altus (“high” or “deep”) and azimuth, derived from the Arabic as‑samt meaning “direction”. The name thus literally describes a device that adjusts height (altitude) and horizontal direction (azimuth).
Characteristics
| Feature | Description |
|---|---|
| Axes of motion | Two perpendicular axes: azimuth (horizontal rotation) and altitude (vertical tilt). |
| Mechanical simplicity | Fewer moving parts than equatorial mounts, resulting in lower cost, lighter weight, and easier maintenance. |
| Tracking requirements | Requires coordinated, often computer‑driven motion in both axes to follow objects across the sky; otherwise, field rotation occurs. |
| Load capacity | Can support a wide range of masses, from handheld binoculars to large, multi‑ton telescope structures. |
| Field rotation | As the instrument tracks, the observed field rotates relative to the detector; this is corrected by field‑derotators or software in imaging applications. |
| Setup | No polar alignment needed; the mount can be placed on virtually any level surface. |
| Applications | Visual observation, astrophotography (with motorized tracking), radio and satellite dish positioning, and some radar systems. |
Related Topics
- Equatorial mount – a telescope mount aligned with Earth’s axis, allowing single‑axis tracking of celestial objects.
- Dobsonian telescope – a type of altazimuth mount using a simple, low‑cost design for large Newtonian reflectors.
- Field derotator – a device that compensates for field rotation in altazimuth‑mounted imaging systems.
- Computerized GoTo system – electronic control that automatically points and tracks objects using altazimuth or equatorial mounts.
- Alt-azimuthal mount (radar) – similar two‑axis mount employed in radar antennas for directional scanning.