Azmuth:    The angular distance around the horizion from Polaris in the clockwise direction to the object of interest. The Azmuth varies from 0° to +359°. The Azmuth is measured in degrees, arc minutes, and arcseconds. This measurement changes depending where the observer is on the face of the Earth.

Celestial Equator:    The imaginary circle in the sky which divides the sky into the norther and southern hemispheres. This circle coincides with the Earth's equator.

Declination(decl):    The angular distance from the  celestial equator to the object of interest. The declination is measured from 0° to ±90°.

Focal Length:    The focal length of a mirror or lens is the distance from the mirror, or lens to the point where image comes to a sharp focus.

Focal Ratio:    The focal ratio is the unobstructed diameter of the opening of the telescope divided by the focal length of the telescope. It is normally written as f/n such as f/11.

Magnitude:    A measure of the amount of light received from a star or other luminous object.

Right Asccension(RA):    The angular distance from the point where the sun crosses the celestial equator from east to west to the object of interest. The RA varies from 0hr to 23hr. The RA is measured in hours, minutes and seconds. One hour of RA is 15°. The RA is constant no matter where the observer is on the face of the Earth.

SCT:    The Schmitt-Cassigrain Telescope is a reflecting telescope which consists of a concave, spherically ground primary mirror and a convex, spherically ground secondary mirror, and a correcting plate. Unlike most other telescopes, the size of a SCT is the unobstructed diameter of the front of the telescope in inches.

UTC:    Universal Time Constant this is the same as Greenwich Mean Time (GMT) UTC is used so that all astronomers all over the world knows what time an astronomical event occurs.