Celestron OMNI XLT 102 Telescope User Manual


 
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Although overlooked by many amateur astronomers, solar observation is both rewarding and fun. However,
because the Sun is so bright, special precautions must be taken when observing our star so as not to damage
your eyes or your telescope.
Never project an image of the Sun through the telescope. Because of the folded optical design (on the SCT),
tremendous heat build-up will result inside the optical tube. This can damage the telescope and/or any
accessories attached to the telescope.
For safe solar viewing, use a solar filter that reduces the intensity of the Sun's light, making it safe to view.
With a filter you can see sunspots as they move across the solar disk and faculae, which are bright patches seen
near the Sun's edge.
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The best time to observe the Sun is in the early morning or late afternoon when the air is cooler.
To center the Sun without looking into the eyepiece, watch the shadow of the telescope tube until it forms a
circular shadow.
To ensure accurate tracking, be sure to select the solar tracking rate of the optional motor drive.
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Deep-sky objects are simply those objects outside the boundaries of our solar system. They include star
clusters, planetary nebulae, diffuse nebulae, double stars and other galaxies outside our own Milky Way. Most
deep-sky objects have a large angular size. Therefore, low-to-moderate power is all you need to see them.
Visually, they are too faint to reveal any of the color seen in long exposure photographs. Instead, they appear
black and white. And, because of their low surface brightness, they should be observed from a dark-sky
location. Light pollution around large urban areas washes out most nebulae making them difficult, if not
impossible, to observe. Light Pollution Reduction filters help reduce the background sky brightness, thus
increasing contrast.
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Viewing conditions affect what you can see through your telescope during an observing session. Conditions
include transparency, sky illumination, and seeing. Understanding viewing conditions and the effect they have
on observing will help you get the most out of your telescope.
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Transparency is the clarity of the atmosphere which is affected by clouds, moisture, and other airborne particles.
Thick cumulus clouds are completely opaque while cirrus can be thin, allowing the light from the brightest stars
through. Hazy skies absorb more light than clear skies making fainter objects harder to see and reducing
contrast on brighter objects. Aerosols ejected into the upper atmosphere from volcanic eruptions also affect
transparency. Ideal conditions are when the night sky is inky black.
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General sky brightening caused by the Moon, aurorae, natural airglow, and light pollution greatly affects
transparency. While this is not a problem for the brighter stars and planets, bright skies reduce the contrast of
extended nebulae making them difficult, if not impossible, to see. To maximize observing, limit deep sky
viewing to moonless nights far from the light polluted skies found around major urban areas. LPR filters
enhance deep sky viewing from light polluted skies by blocking unwanted light while transmitting light from
certain deep sky objects. You can, on the other hand, observe planets and stars from light polluted areas or
when the Moon is out.