Orion 9822 instruction manual Specifications, Finding Objects With the Setting Circles

Figure 8a Figure 8b Figure 8c Figure 8d

Figure 8a,b,c,d. This illustration shows the telescope pointed in the four cardinal directions: (a) North, (b) South, (c) East, (d) West. Note that the tripod and mount have not been moved; only the telescope tube has move on the R.A. and Dec. axis.

circles for finding objects; the thumbscrew is only needed for polar alignment using the polar axis finder scope.

Finding Objects With the Setting Circles

Now that both setting circles are calibrated, look up in a star atlas the coordinates of an object you wish to view.

1.Loosen the Dec. lock lever and rotate the telescope until the Dec. value from the star atlas matches the reading on the Dec. setting circle. Remember that values of the Dec. setting circle are positive when the telescope is pointing north of the celes- tial equator (Dec. = 0°), and negative when the telescope is pointing south of the celestial equator. Retighten the lock lever.

2.Loosen the R.A. lock lever and rotate the telescope until the R.A. value from the star atlas matches the reading on the R.A. setting circle. Remember to use the upper set of num- bers on the R.A. setting circle. Retighten the lock lever.

Most setting circles are not accurate enough to put an object dead-center in the telescope’s eyepiece, but they should place the object somewhere within the field of view of the finder scope, assuming the equatorial mount is accurately polar aligned. Use the slow-motion controls to center the object in the finder scope, and it should appear in the telescope’s field of view.

The R.A. setting circle must be re-calibrated every time you wish to locate a new object. Do so by calibrating the setting circle for the centered object before moving on to the next one.

Confused About Pointing the Telescope?

Beginners occasionally experience some confusion about how to point the telescope overhead or in other directions. In Figure 1 the telescope is pointed north as it would be during polar align- ment. The counterweight shaft is oriented downward. But it will not look like that when the telescope is pointed in other direc- tions. Let’s say you want to view an object that is directly over- head, at the zenith. How do you do it?

DO NOT make any adjustment to the latitude adjustment T-bolts. That will spoil the mount’s polar alignment. Remember, once the mount is polar aligned, the telescope should be moved only on the R.A. and Dec. axes. To point the scope overhead, first loosen the R.A. lock lever and rotate the telescope on the R.A. axis until the counterweight shaft is horizontal (parallel to the ground). Then loosen the Dec. lock lever and rotate the telescope until it is

pointing straight overhead. The counterweight shaft is still hori- zontal. Then retighten both lock levers.

What if you need to aim the telescope directly north, but at an object that is nearer to the horizon than Polaris? You can’t do it with the counterweights down as pictured in Figure 1. Again, you have to rotate the scope in R.A. so that the counterweight shaft is positioned horizontally. Then rotate the scope in Dec. so it points to where you want it near the horizon.

To point the telescope directly south, the counterweight shaft should again be horizontal. Then you simply rotate the scope on the Dec. axis until it points in the south direction.

To point the telescope to the east or west, or in other directions, you rotate the telescope on its R.A. and Dec. axes. Depending on the altitude of the object you want to observe, the counterweight shaft will be oriented somewhere between vertical and horizon- tal.

Figure 8 illustrates how the telescope will look when pointed at the four cardinal directions: north, south, east and west.

The key things to remember when pointing the telescope are that

a)you only move it in R.A. and Dec., not in azimuth or latitude (altitude), and b) the counterweight and shaft will not always appear as it does in Figure 1. In fact it almost never will!

7. Specifications

Mount: German equatorial

Tripod: Aluminum, adjustable height, accessory tray included Counterweights 7lbs. 9oz. and 4lbs.

Slow-motion controls: For both R.A. and Dec. axes

Setting circles: R.A. scaled in 10 min. increments, Dec. scaled in 2° increments. for N or S Hemispheres

Latitude adjustment: 5° to 75°

Motor drives: Optional

Weight: 27.5 lbs.

Polar Alignment: Polar axis finder scope for Northern Hemisphere included, fine adjustments for latitude and azimuth

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