Orion 9862 instruction manual The Polar Axis Finder Scope, Aligning the Polar Axis Finder Scope

Azimuth
fine
adjustment	Tripod
knobs	attachment
		knob

Figure 8. For polar alignment, position the tripod so that the “N” label at the base of the mount faces north. The two azimuth fine adjustment knobs above it are used to make small adjustments to the mount’s azimuth position.

tripod so the telescope points north. There is a label bear- ing a large “N” at the base of the equatorial mount (Figure 8). It should be facing north.

The equatorial mount is now approximately polar-aligned for casual observing. More precise polar alignment is required for astrophotography and for use of the manual setting circles.

From this point on in your observing session, you should not make any further adjustments to the latitude of the mount, nor should you move the tripod. Doing so will undo the polar align- ment. The telescope should be moved only about its R.A. and Dec. axes.

The Polar Axis Finder Scope

A feature of the AstroView 100 EQ is the polar axis finder scope housed inside the R.A. axis of the equatorial mount (see Figure 9). When properly aligned and used, it makes accurate polar alignment quick and easy to do. Alignment of the polar finder need only be done once, unless it gets bumped or oth- erwise shifts its position.

Remove the cover cap from the front opening in the R.A. axis of the mount (see Figure 6). Look through the polar finder at a distant object. Focus the polar finder so that the images and reticle are sharp by rotating the eyepiece end of the finder. Notice that the reticle pattern consists of a crosshair with a circle around the middle. On the circumference of this circle is a tiny circle; this is where Polaris will be placed for accurate polar alignment once the finder is properly aligned. Alignment of the polar finder is best done during the day, before going out into the field at night.

Aligning the Polar Axis Finder Scope

Aligning the polar axis finder scope so that it will accurately point at the true north pole is a two-step procedure. First, the polar finder must be rotated in its housing so that the small circle in which Polaris will be placed in is in the proper initial position. Next, the polar axis finder must be adjusted so that it points directly along the mount’s R.A. axis.

R.A. setting circle lock thumbscrew

					Pointer
Date circle	R.A. setting circle
			Meridian
Ring with			offset scale
engraved time
meridian indicator
mark			Polar scope
Polar scope				housing
alignment			Polar axis
thumbscrew (3)
		finder scope

Figure 9. The polar axis finder scope installed in the right ascension (R.A.) axis of the mount.

We will start by aligning the polar finder rotationally. Refer to Figure 9.

1.Loosen the large thumbscrew just above the R.A. setting circle. Rotate the R.A. setting circle until the line above the “0” on the setting circle lines up with the pointed indicator that is cast into the mount (located directly below the large thumbscrew; see Figure 8). Retighten the thumbscrew.

2.Rotate the date circle until the “0” line on the meridian off- set scale lines up with the time meridian indicator mark. The meridian offset scale is printed on the inner circumfer- ence of the date circle, and is labeled “E20” to “W20”. The time meridian indicator mark is an engraved line on the exterior of the polar finder’s housing. It is on the “ring” of the housing that is closest to the date circle.

3.The R.A. setting circle is labeled in hours, from “0” to “23” (military time). For Northern Hemisphere observers, refer to the top numbers on the setting circle. Each small line represents 10 minutes of R.A. The date circle is labeled from “1” to “12”, with each number representing a month of the year (“1” is January, “2” is February, etc.). Each small line represents a two-day increment.

4.Loosen the R.A. lock lever and rotate the mount about the R.A. axis until the March 1 indicating mark (the long line between the “2” and the “3”) on the date circle lines up with the 4 PM mark (the long line above the “16”) on the R.A. setting circle.You may find it convenient to remove both the counterweights and the telescope optical tube to do this.

5.Now, loosen the three thumbscrews on the polar finder housing and rotate the polar finder so the small circle where Polaris will be centered is located straight down from the intersection of the crosshairs. Retighten the thumbscrews.

The polar axis finder scope is now properly set in its initial position. Next, you must align it so that it is exactly parallel to the mount’s R.A. axis:

6.Look through the polar finder at a distant object (during the day) and center it in the crosshairs.You may need to adjust the latitude adjustment T-bolts and the tripod position to do this.

8