Assessments - 1, GPA: 3
(
)
)
|
Facilidade de uso
Rotate the telescope until the polar axis (10) points due North. Use a compass or locate Polaris, the North Star (see Fig. 3), as an accurate reference for due North. 2) Level the mount, if necessary, by adjusting the heights of the three tripod legs. 3) Determine the latitude of your observing location by checking a road map or atlas. Release the latitude lock (9) and tilt the telescope mount with the latitude adjustment knob (11) so that the pointer indicates the correct latitude of your viewing location on the latitude scale (29). Re-tighten the latitude lock (9). 4) If steps (1) - (3) above were performed with reasonable accuracy, your telescope is now sufficiently well- aligned to the North Celestial Pole for visual observations. Once the mount has been polar-aligned as described above, the latitude angle need not be adjusted again, unless you move to a different geographical location (i.e. a different latitude). The only polar alignment procedure that need be done each time you use the telescope is to point the polar axis due North, as described in step (1) above. E. Using the Telescope With the telescope assembled, balanced and polar aligned as described above, you are ready to begin observations. Decide on an easy-to-find object such as the Moon, if it is visible, or a bright star to become accustomed to the functions and operations of the telescope. For the best results during observations, follow the suggestions below: – 10 – • To center an object in the main telescope, loosen the telescope’s R.A. lock (22) and Dec. lock (23). The telescope can now turn freely on its axes. Use the aligned viewfinder to first sight-in on the object you wish to observe; with the object centered on the viewfinder’s crosshairs, re-tighten the R.A. and Dec. locks. • If you have purchased an assortment of eyepieces (see Section G on Calculating Power and Section J on Optional Accessories for higher and lower powers with the telescope), always start an observation with a low power eyepiece (e.g. the MA25mm eyepiece); get the object well-centered in the field of view and sharply focused. Then try the next step up in magnification. If the image starts to become fuzzy as you work into higher magnifications, then back down to a lower power; the atmospheric steadiness is not sufficient to support high powers at the time you are observing. Keep in mind that a bright, clearly resolved but smaller image will show far more detail than a dimmer, poorly resolved larger image. The MA25mm eyepiece included with the Model 4500 presents a wide field of view, ideal for general astronomical observing of star fields, clusters of stars, nebulae, and galaxies; it is also probably the best eyepiece to use in the initial finding and centering of any object. • Once centered, the object can be focused by turning one of the knobs of the focusing mechanism (31). You will notice that the astronomical object in the field of view will begin to slowly move across the eyepiece field. This motion is caused by the rotation of the Earth on its axis, as described in Section C, although the planets and stars, are, for practical purposes, fixed in their positions in the sky. The platform on which the telescope is sitting ( the Earth) rotates once every 24 hours under these objects.To keep astronomical objects centered in the field of the polar aligned telescope, simply turn the R.A. flexible cable control (3).These objects will appear to move through the field more rapidly at higher powers. Note that the Declination flexible cable control is used only for centering purposes, and not for tracking. • Avoid touching the eyepiece while observing through the telescope. Vibrations resulting from such contact will cause the image to move. Likewise, avoid observing sites where ground-based vibrations may resonate the tripod. Viewing from the upper floors of a building may also introduce image movement. • You should allow a few minutes to allow your eyes to become “dark adapted” before attempting any serious astronomical observations. Use a red filtered flashlight to protect your night vision when reading star maps or inspecting the components of the telescope. • Avoid setting up the telescope inside a room and observing through an open window (or worse yet, a closed window). Images viewed in such a manner may appear blurred or distorted due to temperature differences between inside and outside air. Also, it is a good idea to allow your telescope a chance to reach the ambient (surrounding) outside temperature before starting an observing session. We repeat the warning stated at the outset of this manual: Never point the telescope directly at or near the Sun at any time! Observing the Sun, even for the smallest fraction of a second, will result in instant and irreversible eye damage, as well as physical damage to the telescope itself. • Avoid viewing objects low on the horizon–objects will appear better resolved with far greater contrast when viewed higher in the sky...