Telescope mount

A mechanical support that holds and moves a telescope, allowing it to point at and track celestial objects. Its design determines how the telescope moves and how it compensates for Earth’s rotation.

Equatorial mount: A telescope mount with one axis aligned parallel to Earth’s rotation axis, enabling tracking by rotating around that axis. Its polar-aligned axis can follow the sky with a steady rotation.
Polar alignment: The process of aligning an equatorial telescope mount’s polar axis with Earth’s rotational axis. Accurate alignment lets the mount track with minimal correction.
German equatorial mount: An equatorial mount whose telescope and counterweight sit on opposite sides of a central declination axis. Its counterweighted design supports substantial telescopes but requires a meridian flip.
Astrophotography: The practice of photographing astronomical objects and phenomena. Long exposures require stable tracking and careful control of mount errors.
Altazimuth mount: A telescope mount that moves in altitude and azimuth, corresponding to vertical angle and compass direction. Its two perpendicular axes provide a simple way to aim across the sky.
Celestial sphere: An imaginary sphere surrounding Earth on which celestial objects are represented by directions. Mounts aim by translating directions on this model into mechanical positions.
Fork mount: A mount in which a telescope sits between two arms attached to a rotating base. Fork designs can operate in altazimuth or equatorial configurations, unlike a single universal geometry.
Periodic error: A repeating tracking error caused by imperfections in a telescope mount’s drive mechanism. It produces recurring deviations that can blur long-exposure images.
Right ascension: The angular coordinate measured eastward along the celestial equator from the vernal equinox. On an equatorial mount, this coordinate tracks celestial motion around the polar axis.
Sidereal time: A timekeeping system based on Earth’s rotation relative to distant stars. Equatorial tracking follows the sky’s apparent motion at the sidereal rate.

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