You are here


Equatorial Mountings: Although celestial objects are essentially fixed in their positions in the sky (on the celestial sphere, the imaginary spherical surface on which all astronomical objects are located), they appear to move in an arc across the sky, as the earth rotates underneath the sky once every 24 hours. From an astronomical point of view, therefore, the task of the telescope mounting is to compensate for the Earth's rotation and allow the observer to track the Moon, planets, and stars. This task is made vastly easier by the equatorial mounting, the type of mounting incorporated into most larger or more advanced telescopes. By aligning one axis of the equatorial mount to the Earth's rotational axis (a simple process which involves pointing one telescope axis to the North Star), the observer can track astronomical objects by turning one control cable, instead of the two simultaneous motions required with the altazimuth mount. If a small motor is attached to the equatorial mount, this tracking can be performed automatically. These motor drives are available for most Meade equatorially mounted telescopes The equatorial mount is the most common type of mount available with today's telescopes. It is pretty much standard with both reflectors and refractors. This mount consists of two perpendicular axes. One axis rotates the telescope in Right Ascension (R.A.), and the other controls Declination (Dec.). When the R.A. axis is aligned parallel to the Earth's axis, objects can be tracked by adjusting slow motion controls that move the mount on the R.A. axis. These mounts are available with motors attached to the R.A. axis that enable automatic tracking of objects in the sky. To accomplish this, the mount will rotate the telescope in the opposite direction as the rotation of the Earth. This allows an object to remain centered in the telescope for prolonged periods of time. These mounts also contain coordinate markings called setting circles. These coordinates enable objects to be located by their celestial coordinates using the R.A. and Dec. setting circles.