morning hours, before the ground has built up internal heat, results in better viewing conditions than during the late- afternoon hours.
If you wish to observe a distant land object, such as a mountain top or a bird, you can observe by merely pointing the telescope and looking through the eyepiece. Set the telescope on a table top or tripod, loosen the horizontal and vertical locks (6 and 9, Fig. 1), and turn
Polaris | Right | Ascension |
| Declination | |
|
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the telescope towards the object you | Fig. 10: Equatorial mounting aligns the telescope with the | |
wish to observe. Look into the viewfinder | ||
celestial sphere | ||
and move the tube until you find the |
| |
| ||
object. If the viewfinder is correctly |
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aligned, the object now appears in the eyepiece. Center the object and focus the image using the by turning the focus knob (8, Fig. 1). Rotate the knob clockwise to focus on distant objects and counterclockwise to focus on nearby objects.
Astronomical Observing
As an astronomical instrument, your ETX telescope has many optical and electromechanical capabilities. It is in astronomical applications where the high level of optical performance is readily visible. The range of observable astronomical objects is, with minor qualification, limited only by the observer’s motivation.
Sidereal Rate
As the Earth rotates beneath the night sky, the stars appear to move from East to West. The speed at which the stars move across the sky is called the sidereal rate.
You can observe stars and objects in the night sky using the terrestrial viewing method, but note that objects begin to slowly drift across and out of the eyepiece field. This motion is caused by the rotation of the Earth.
Fig. 11: Electronic Controller.
You can counteract the drift by mounting the telescope to one of the optional tripods in the
polar mode (see POLAR ALIGNMENT
PROCEDURE, page 16). In this mode, the motor drive in each ETX model is designed to rotate the telescope at the sidereal rate so that it automatically follows, that is, "tracks" the stars. Tracking makes it easier to locate objects and to keep them centered in the telescope’s eyepiece. The Electronic Controller supplied with your telescope assists with the tracking function.
The Electronic Controller
Functions of the Electronic Controller include:
•Slewing (moving) the telescope's optical tube assembly to an object
•Turning on the telescope motor drive to automatically track celestial objects (when the telescope is polar aligned)
•Changing the hemisphere of operation, when required
•Changing tracking speed (see APPENDIX A, page 26)
Slew Speeds
The Electronic Controller has four slew speeds that are directly proportional to the sidereal rate. Press the Speed key to change the slew speed. Note each slew speed corresponds to one of the four LED's of the Electronic Controller.
TIPS FOR BEGINNERS 
•Try to pick an observing site away from street and house lights, and car headlights. While this is not always possible, the darker the site, the better.
•Give your eyes about ten minutes to adjust to the darkness before observing. Give your eyes a rest from observing every ten or fifteen minutes to relieve eyestrain.
•Try not to use a standard flashlight. Seasoned observers use red LED flashlights or tape red cellophane over their flashlights for setup and map reading so they don’t have to continually readjust their eyes to the darkness. Be careful not to shine bright lights if there are other observers in the area. Never shine a flashlight into a telescope while someone is observing!
•Dress warmly. It gets chilly when you’re sitting for prolonged periods, even on some summer nights.
•Practice setting up your equipment during the day or in a lighted area to become familiar with it before going to a dark site.
•Use your 26mm eyepiece to view terrestrial objects and wider areas of space, such as open star clusters. Use your higher power eyepieces when you wish to view something up close, such as craters on the Moon or the rings of Saturn.
•Know your observing site. If you’re going to try out an unfamiliar site, check it out in the daylight for possible obstructions and pitfalls.
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