Orion 9791 Selecting an Observing Site, Use of the Optional Light Shroud, Seeing and Transparency

your target much more quickly (and quietly!) than other com- puterized telescopes can – and without guzzling all those bat- teries in the process.

The Object Locator’s database includes:

•7,840 objects from the Revised New General Catalog (NGC)

•5,386 objects from the Index Catalog (IC)

•110 objects from the Messier Catalog (M)

•837 selected stars (mostly double, multiple, and variable stars)

•8 planets

•99 user-programmable objects

With the user-friendly IntelliScope Object Locator, there are many ways to locate an astronomical object. If you know its catalog number (NGC or M number, for instance), you can enter it using the illuminated keypad buttons. Or you can press one of the object category buttons (Cluster, Nebula, Galaxy, etc.) to access a list of objects by type. For a tour of the best objects visible in a given month, you just press the Tour button.

Another great feature of the IntelliScope is the ability to iden- tify an “unknown” object in the field of view – just press the ID button. You can even add up to 99 objects of your own choosing to the Object Locator’s database. The backlit, two- line LCD on the Object Locator shows you the object’s cata- log number, its common name if it has one, the constellation in which it resides, its right ascension and declination coordi- nates, the object type, magnitude, angular size, as well as a brief description in scrolling text.

The IntelliScope Object Locator is a wonderful convenience for both the novice and experienced observer. You’ll spend more time actually observing astronomical objects instead of hunting for them. For instructions on how to operate the Object Locator, refer to the instruction manual included in the box with the IntelliScope Object Locator kit.

Selecting an Observing Site

Since most astronomical objects are faint, observing them from dark skies will give you the best views. While some objects, such as the planets and Moon, are bright enough to see clearly even from light-polluted city skies, for nebulas, galaxies, and most star clusters, the less ambient light there is to reduce contrast, the better.

When it isn’t possible or convenient to get out of town to a pitch-black observing location, try to set up in a spot that is removed from street and building lights and that has a clear view of a large portion of the sky. Avoid pointing the tele- scope above buildings, if possible, since they radiate heat which degrades images. For observing faint deep sky objects, choose a moonless night or time of night. Using the optional light shroud will be a necessity (see below). Also, use of a light-pollution filter, like the Orion SkyGlow Broadband fil- ter, can mitigate the effects of background sky brightness, enhancing the view of faint objects.

Figure 48. The optional light shroud for the XX14i prevents stray light from entering the telescope. It also helps prevent dew from forming on the optical surfaces.

Use of the Optional Light Shroud

When viewing from light-polluted skies, we highly recommend using the optional light shroud for the XX14i. The light shroud is a black nylon cloth wrap that fits over the exterior of the truss poles (Figure 48). The shroud prevents stray light from entering the telescope through the open truss section of the tube and degrading image contrast. The shroud also helps prevent dew from forming on the optical surfaces of the tele- scope.

Seeing and Transparency

Atmospheric conditions play a huge part in quality of viewing. Light from stars and other celestial objects must travel through miles of Earth’s atmosphere to reach our eyes. The air in the atmosphere will refract and bend the light. Atmospheric turbu- lence will worsen the effects of refraction, which can cause the image you see in your telescope to be unstable. The steadi- ness of the atmosphere is called the “seeing” condition.

In conditions of good seeing, star twinkling is minimal and objects appear steady in the eyepiece. Seeing is best over- head, worst at the horizon. Also, seeing conditions generally

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