A mount with two axes, one vertical (azimuth) and one horizontal (altitude), like a photo tripod. Intuitive and with no polar alignment, it needs both axes moved to follow an object. In long-exposure imaging the field rotates as the minutes pass.
Related terms
- Equatorial mount
A mount with one axis (the right ascension, or polar, axis) parallel to the Earth’s axis of rotation. Once polar aligned, turning that single axis follows the stars, by hand or with a motor. The “German” type, with counterweights, is the most common.
- Dobsonian
A Newtonian telescope on a simple box base that swings up and down and turns round, popularised by John Dobson in the 1960s and 1970s. You nudge it by hand to follow objects. Quick to set up and very steady, it gives a beginner the largest aperture.
- Altitude
The angle between an object and the horizon, from 0° (on the horizon) to 90° (at the zenith); also called elevation. Objects are usually well placed above 30°. With azimuth it locates an object in your local sky.
- Azimuth
An object’s direction along the horizon, measured from north towards east: 0° north, 90° east, 180° south, 270° west. With altitude it tells you where to look. Some older books count it from the south: check the convention.
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