Altazimuth

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A Dobsonian telescope on an azimuthal “rocker box” mount
Altazimuth in geodesy

Altazimuth or azimuthal mount is the simplest type of astronomical telescope mount , in which the telescope can be pivoted in all directions around a vertical standing axis and a horizontal tilting axis. Its counterpart is the equatorial mount , where the primary axis is not vertical , but parallel to the earth's axis.

The name Altazimut , which is also abbreviated Altaz in English , is made up of Alt for Altitude ( elevation angle ) and Azimuth ( horizontal angle ).

Azimuthal mounts have been used for astronomical and geodetic measuring instruments since ancient times because of their robust, simple design . After the invention of astronomical telescopes , they were also used for these from around 1620 and were increasingly perfected by the 18th century. Then they were replaced by the equatorial or parallactic mount; Only with the modern large telescopes , whose mirror diameters range from 6 to 20 meters, did they return to this earlier design around 1980 for reasons of mechanical stability .

In astronomy , in addition to the newer, very large telescopes (from about 6 m mirror diameter) and the radio telescopes , the universal and passage instruments are also mounted azimuthally, as are the meridian circles and heliostats , most meteor cameras and the ballistic satellite cameras . The latter are sometimes also used as astrographs .

In geodesy (surveying) and generally in technology , the Altaz system predominates over all other mounts because it corresponds to the natural plumb line and the horizon and can be easily adjusted - e.g. B. with dragonflies or inclinometers - can be set up precisely. Important examples are