Telescope mount
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In astronomy, the telescope mount is an important part of the overall design of an operational telescope. Many sorts of mounts have been developed over the years, with the majority of effort being put into systems that can track the motion of the stars as the Earth rotates with a single motion.
The earliest types of mounts are today known as altitude-azimuth, or alt-az systems. The name refers to the way the system allows the telescope to be moved in altitude, up and down, or azimuth, side to side, as separate motions. They typically consisted of a two-prong fork with the telescope sitting between the prongs. Alternate alt-az systems used a single large pipe as one axis, typically the az, with the telescope mounted on a second pipe perpendicular to the first.
The introduction of the equatorial mount displaced most alt-az systems for serious users. By tilting the horizontal base of an alt-az system up until it is parallel to Earth's equatorial plane, the azimuth rotation then swings the telescope in an arc that follows the stars as they move across the sky due to Earth's rotation. By attaching a simple clockwork mechanism to this axis, the equatorial system makes long observation easy. The German equatorial is the most popular form, consisting of two rods mounted in a T, with the telescope on the end of one of the T arms and the body tilted to match Earth's axis.
Today, the alt-az system is making a comeback in the form of the Dobsonian, a simplified and very rugged alt-az mount. The introduction of better electronics and inexpensive driver motors has allowed even alt-az systems to track the stars, making the complexity of the equatorial system less important.