User manual ORION TELESCOPES & BINOCULARS SKYQUEST XT4.5

[. . . ] INSTRUCTION MANUAL Orion SkyQuest XT4. 5 Dobsonian Reflector ® TM #9804 Customer Support (800) 676-1343 E-mail: support@telescope. com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P. O. Box 1815, Santa Cruz, CA 95061 IN 164 Rev. A Secondary mirror holder with 4-vane spider (not visible) Finder scope Finder scope bracket Focuser Eyepiece Navigation Knob Altitude Side Bearing Carry handle CorrecTension system Eyepiece rack Primary mirror cell Plastic foot Figure 1. The SkyQuest XT4. 5 parts diagram. Welcome to an exciting new world of adventure! Your SkyQuest XT4. 5 Dobsonian is a high-quality optical instrument designed to bring you dazzling views of the outer reaches of our universe. Easy enough for kids to use, and portable enough for anyone to carry, the SkyQuest XT4. 5 will provide fun and entertainment for the entire family. [. . . ] This is because the heat from the Sun warms the air and causes turbulence. Good "transparency" is especially important for observing faint objects. It simply means the air is free of moisture, smoke, and dust which tend to scatter light, reducing an object's brightness. One good way to tell if conditions are good is by how many stars you can see with your naked eye. If you cannot see stars of magnitude 3. 5 or dimmer then conditions are poor. 3. 4), which is the star in the `Big Dipper' connecting the handle to the `dipper'. If you cannot see Megrez, then you have fog, haze, clouds, smog, or other conditions that are hindering your viewing. (See Figure 14) Let Your Eyes Dark-Adapt Do not expect to go from a lighted house into the darkness of the outdoors at night and immediately see faint nebulas, galaxies, and star clusters -- or even very many stars, for that matter. Your eyes take about 30 minutes to reach perhaps 80% of their full dark-adapted sensitivity. Many observers notice improvements after several hours of total darkness. As your eyes become dark-adapted, more stars will glimmer into view and you will be able to see fainter details in objects you view in your telescope. So give yourself at least a little while to get used to the dark before you begin observing. To see what you are doing in the darkness, use a red light flashlight rather than a white light. Red light does not spoil your eyes' dark adaptation like white light does. A flashlight with a red LED light is ideal, or you can cover the front of a regular flashlight with red cellophane or paper. Beware, too, that nearby porch and streetlights and automobile headlights will spoil your night vision. 5 Astronomy Basics Tracking Celestial Objects The Earth is constantly rotating about its polar axis, completing one full rotation every 24 hours; this is what defines a "day". We do not feel the Earth rotating, but we can tell that it is at night by seeing the apparent movement of stars from east to west. This movement translates into a rate of approximately . 25° per minute, or 15 arc-seconds per second. (There are 60 arc-minutes in 1°, and 60 arc-seconds in one arc-minute. ) This is called the sidereal rate. When you observe any astronomical object, you are watching a moving target. This means the telescope's position must be continuously updated over time to keep an object in the field of view. This is easy to do with the SkyQuest XT4. 5 because of its smooth motions on both axes. [. . . ] Do this by holding the secondary mirror holder stationary with your fingers (don't touch the mirror itself) while unthreading the Phillips head cap screw in the center hub of the 4-vaned spider. Completely unthread the screw from the holder, and the holder will come loose in your fingers. Be careful not to lose the spring on the Phillips head cap screw. Handle the mirror and its holder carefully. You do not need to remove the secondary mirror from its holder for cleaning. [. . . ]