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William Herschel's 49-inch (1,200 mm) 40-foot telescope on an altazimuth mount. Altazimuth, altitude-azimuth, or alt-az mounts allow telescopes to be moved in altitude (up and down), or azimuth (side to side), as separate motions. This mechanically simple mount was used in early telescope designs and until the second half of the 20th century ...
In the largest telescopes, the mass and cost of an equatorial mount is prohibitive and they have been superseded by computer-controlled altazimuth mounts. [5] The simple structure of an altazimuth mount allows significant cost reductions, in spite of the additional cost associated with the more complex tracking and image-orienting mechanisms. [6]
A large German equatorial mount on the Forststernwarte Jena 50cm Cassegrain reflector telescope. An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, called polar axis, parallel to the Earth's axis of rotation. [1] [2] This type of mount is used for astronomical telescopes and cameras.
The altazimuth mount does have its own limitations. Un-driven altazimuth mounted telescopes need to be "nudged" every few minutes along both axes to compensate for the rotation of the Earth to keep an object in view (as opposed to one axis for un-driven equatorial mounts), an exercise that becomes more difficult with higher magnifications. [11]
Altitude (alt. or altitude angle [b]), sometimes referred to as elevation (el. or elevation angle [c]) or apparent height, is the angle between the object and the observer's local horizon. For visible objects, it is an angle between 0° and 90°. [d]
A large portable Newtonian telescope on an altazimuth mount with a third equatorial axis platform mount consisting of a pivot and radius bearing surfaces.. An equatorial platform or equatorial table is an equatorial telescope mount in the form of a specially designed platform that allows any device sitting on it to track astronomical objects in the sky on an equatorial axis. [1]
They include commercial equatorial mounts and homemade equatorial devices such as barn door trackers and equatorial platforms. Mounts can suffer from inaccuracies due to backlash in the gears, wind, and imperfect balance, and so a technique called auto guiding is used as a closed feedback system to correct for these inaccuracies.
Altazimuth mount, a two-axis telescope mount Topics referred to by the same term This disambiguation page lists articles associated with the title Altitude-azimuth .