Orion 9874 Operation of the Atlas Mount Motor Drives, Atlas EQ Mount hand controller

Figure 10. The optical tube must be at a 90° angle to the R.A. axis in order to view through the polar axis finder.

Power switch

Indicator light

R.A. pushbuttons

Rate switch

Reverse switches

Dec. pushbuttons

quick and easy. To align the mount using the polar axis finder scope, follow these instructions:

1.Approximately polar-align the mount as outlined in the pre‑ vious alignment procedure.

2.Loosen the Dec. lock lever and rotate the optical tube on the declination axis so that the tube is at a 90° to the right ascension axis (Figure 10). Tighten the Dec. lock lever.

3.Remove the cap on the front opening of the equatorial mount (Figure 7). Focus the polar finder by rotating the eyepiece. Now, sight Polaris in the polar axis finder scope. If you have followed the approximate polar alignment pro‑ cedure accurately, Polaris will probably be within the field of view. If not, move the tripod left-to-right, and adjust the latitude up-and down until Polaris is somewhere within the field of view of the polar axis finder scope.

4.Flip the power switch on the hand controller (Figure 11) to the N or S position. With the power on, you can now use the illuminator on the polar axis reticle. Look through the polar axis finder and adjust the illuminator by turning the small dial on the mount (located above the power and hand controller jacks) counter-clockwise to make it bright‑ er, and clockwise to make it dimmer. Use the dimmest possible setting that allows you to see the reticle without difficulty. Note the constellation Cassiopeia and the Big Dipper in the reticle. They do not appear in scale, but they indicate the general positions of Cassiopeia and the Big Dipper relative to the north celestial pole (which is indi‑ cated by the cross at the center of the reticle). Rotate the reticle so the constellations depicted match their current orientation in they sky when viewed with the naked eye. To do this, release the R.A. lock lever and rotate the main telescope around the R.A. axis until the reticle is oriented with sky. You may need to remove the tube from the mount to prevent it from bumping into the mount. Once the reticle is correctly oriented, use the right ascension lock lever to secure the mount’s position.

5.Now use the azimuth adjustment knobs (Figure 2) and the latitude adjustment L-bolts (Figure 7) on the mount to position the star Polaris inside the tiny circle marked

Figure 11. The Atlas EQ Mount hand controller.

“Polaris” on the finder’s reticle. You must first loosen the knob underneath the equatorial mount on the center sup‑ port shaft to use the azimuth adjustment knobs. Once Polaris is properly positioned within the reticle, you are precisely polar aligned.

If you do not have a clear view of Polaris from your observing site, you will not be able to use the polar axis finder to pre‑ cisely polar align the telescope.

From this point on in your observing session, you should not make any further adjustments in the azimuth or the latitude of the mount, nor should you move the tripod. Doing so will undo the polar alignment. The telescope should be moved only about its right ascension and declination axes.

Additional Note Regarding Focusing the Polar Axis Finder Scope

The polar axis finder scope is normally focused by simply rotating the eyepiece focus ring. However, if after adjusting the focus ring you find that the image of the reticle is sharp, but the stars are out of focus, then you must adjust the focus of the polar axis finder’s objective lens. To do this, first remove the polar axis finder from the mount. Look through the polar axis finder at a star (at night) or distant object at least 1/4 mile away (during daylight). Use the eyepiece focus ring to bring the reticle into sharp focus. Now, loosen the focus lock ring (Figure 9) and thread the entire objective end of the finder inwards or outwards until images appear sharp. Re-tighten the focus lock ring. Once the polar axis finder’s objective lens is focused, it should not need to be adjusted again.

Operation of the Atlas Mount Motor Drives

The Atlas EQ mount comes with dual built-in motor drives. These motor drives will be used to “track” objects in the night sky, as well as to make small adjustments when aiming the telescope. The motors are controlled from the hand controller (Figure 11). To start the drives, flip the power switch on the hand controller to “N” if you live in the northern hemisphere, or “S” if you live in the southern hemisphere. When you flip

9