Celestron XLT series User Manual
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Resolution
The minimum detectable angle an optical system can detect. Because of diffraction, there is a limit
to the minimum angle, resolution. The larger the aperture, the better the resolution.
T
he ang
Right Ascension: (RA)
ular distance of a celestial object measured in hours, minutes, and seconds along the
elestial Equator eastward from the Vernal Equinox.
S -
idt Telescope
Rated the most important advance in optics in 200 years, the Schmidt telescope combines the best
Voldemar Schmidt (1879-1935).
Sidereal Rate
This is the angular speed at which the Earth is rotating. Telescope tracking motors drive the
telescope at this rate. The rate is 15 arc seconds per second or 15 degrees per hour.
the light and dark portion of the moon or a planet.
V -
ble Star
A star whose brightness varies over time due to either inherent properties of the star or something
W -
Waning Moon
Waxing Moon
Z -
Zodiac
years
nal Equinox has moved westward by
about 30 deg
rees
since that time; the signs have moved with it and thus no longer coincide with the
C
Schm
features of the refractor and reflector for photographic purposes. It was invented in 1930 by
Bernhard
T -
Terminator
The
boundary
line between
U -
Universe
The totality of astronomical things, events, relations and energies capable of being described
objectively.
Varia
eclipsing or obscuring the brightness of the star.
The period of the moon's cycle between full and new, when its illuminated portion is decreasing.
The period of the moon's cycle between new and full, when its illuminated portion is increasing.
Zenith
The point on the Celestial Sphere directly above the observer.
The zodiac is the portion of the Celestial Sphere that lies within 8 deg
rees
on either side of the
Ecliptic. The apparent paths of the Sun, the Moon, and the planets, with the exception of some
portions of the path of Pluto, lie within this band. Twelve divisions, or signs, each 30 deg
rees
in
width, comprise the zodiac. These signs coincided with the zodiacal constellations about 2,000
ago. Because of the Precession of the Earth's axis, the Ver
constellations.
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