Meade LXD55 Series, Instruction Manual

50

APPENDIX B: ENHANCING
POINTING PRECISION

The Polar Alignment Viewfinder

Typically Autostar's pointing capabilities are sufficient for most telescope observers,
and the use of the polar alignment viewfinder is unnecessary for them. However, for
those observers who need to meet the more demanding requirements of astropho-
tography, the polar alignment viewfinder allows the telescope mount to be more pre-
cisely aligned with true North. The polar alignment viewfinder contains a reticle, lit by
an LED (Figs. 36 and 37).

To align your telescope to North using the polar alignment viewfinder:

1.

Set your telescope in the home position (see page 17). Then loosen the Dec.
lock (17, Fig. 1d) and rotate the optical tube 90°. Re-tighten the Dec. Lock.

2.

Loosen the R.A. Lock (33, Fig. 1d).

3.

Remove the polar viewfinder cap (18, Fig. 1d).

4.

If you have not already done so, remove the plastic separating the watch batter-
ies inside the polar alignment reticle. See step 12, page 13. 

5.

Turn the polar alignment reticle LED knob to turn on the LED and look through
the reticle. 

6.

Northern Hemisphere: Move the telescope mount until Polaris is superimposed
on the graduated area of the reticle (between 40' and 60'). The center crosshair
denotes the North celestial pole. Southern Hemisphere: The four-sided figure in
the reticle represents a grouping of four stars in Octantis (Sigma, Tau, Chi, and
Upsilon) for use in the Southern Hemisphere. Move the telescope mount on its
R.A. axis until the four stars depicted in the reticle are superimposed on the four
star group that matches the reticle pattern.

7.

Use the latitude T-handle screws (26, Fig. 1d) and the fine azimuth control knobs
(27, Fig. 1d) to fine tune the mount adjustment until the reticle pattern is more
precisely superimposed over the appropriate position as described in step 6. 

Note: Not all pointing positions are possible with the polar alignment reticle,
as the tripod is a limiting factor as to how far the optical tube and mount can
be moved.

8.

Tighten the R.A. Lock (33, Fig. 1d). Return the optical tube to the home position.

Note: Remember to turn off the polar alignment reticle LED.

Axis Alignment Procedure

In order for the equatorial mount to accurately point to astronomical objects using the
GO TO feature of the Autostar handbox, the optical axis of the optical tube must be
aligned with the R.A. axis of the mount. In most cases, the telescope will perform
adequately without making any adjustments, but performing one of the following
alignment methods before the initial use of the telescope, and periodically thereafter,
will increase the mount’s pointing accuracy.

When the optical axis is perfectly aligned to the R.A. axis and the declination set to 90°,
all objects will rotate about a point in the center of the eyepiece, as the mount is rotated
about the R.A. axis. A misalignment in elevation results in the center of rotation shifting
up or down. A misalignment in attitude results in the center shifting left or right.

The telescope is moved manually in Method #1 to correct for attitude misalignment
and then for elevation misalignment. Autostar moves the telescope in Method #2; this
method is recommended for beginners.

Method 1: Manual Alignment

Procedure #1: To correct for attitude misalignment

Important Note: Throughout the following procedures, the directional refer-
ences up/down/left/right are used. No matter which type of telescope model
you are using, these directions are to be interpreted relative to real-world
targets. For example, left/right moves the image along the horizon, and
up/down moves the image vertically.

Perform this procedure during the daytime. You will need to have a clear line of
sight to a wide, distinct landmark with a clear, horizontal feature.

1.  Plug in Autostar and turn on the power as described previously in this manual.

You will use Autostar's Arrow keys in the course of this procedure.

Fig. 36: The polar alignment
viewfinder.

Reticle LED Knob

Eyepiece

Fig. 37: The view inside the polar
alignment viewfinder reticle.

Fig. 38: A. Elevation Alignment;
B. Attitude Alignment.