Polar Alignment

There are several means of aligning your mount. One of the easiest and generally accurate means is through a polar alignment scope. These are either inserted directly into the polar shaft or attached to it. The eyepiece contains an illuminated reticle that shows you exactly where to position Polaris and the second brightest star in the field. Once this is accomplished, you are well aligned.

If you do not have a polar alignment scope, you can rely on your mount’s setting circles. To do this, you will need to position the mount so that the polar axis points toward the celestial pole. Make sure that your Declination circle reads 90 when that axis lies on the same plane as the polar axis (i.e., when your telescope is pointing along the polar axis). Then point your scope at a star near the celestial equator and set the Right Ascension circle so it reads the correct coordinates for that star. Next, reposition the scope until the setting circles read the coordinates for Polaris (R.A. 2h 21m, Dec. +89degrees 13m). Finally, move the entire mount until Polaris is centered in your eyepiece’s field of view.

Yet another method of polar alignment is referred to as declination drift. This method is time-consuming but yields the most accurate results. You will need to begin by finding two bright stars, one near the eastern horizon and the other near the meridian (due south). Both stars should be near the celestial equator. Place an illuminated reticle eyepiece into the diagonal and position it so the crosshairs are aligned with the R.A. and Dec axes (do so by slewing the scope). Next, find the star that is near the intersection of the celestial equator and the meridian. Center that star in your eyepiece and monitor its movement (drift) along declination. If it drifts south, the polar axis is too far east; if it drifts north, the polar axis is too far west. Make the necessary adjustments to the mount to eliminate any further drift and then center your scope on the star that is near the eastern horizon. Now observe that star’s drift in declination. If it drifts south, the axis is pointed too low; if it drifts north, the axis is pointed too high. Once again, adjust the mount to eliminate the drift. Unfortunately, this entire process will need to be repeated as adjustments in one axis affect the other. Once there is minimal drift with both stars, the mount is accurately aligned.

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