Optical Tube Alignment Procedure to
Improve Meade LX200 Pointing Accuracy
by Michael Sparks <sparksmd
zoomnet.net>
A misaligned Optical Tube Assembly (OTA) will significantly reduce the pointing accuracy of your LX200. The purpose of this document is to give the owner of an LX200 with poor pointing accuracy the option to attempt to correct this problem himself before sending his scope to Meade for realignment. This document assumes that the owner is familiar with his scope and has an average mechanical aptitude.
Basis for this procedure
The pointing accuracy of an LX200 is dependent on two general areas of
scope design, the electrical and the mechanical. The electrical is concerned
with the on board computer and encoders while the mechanical is concerned
with the relationship between the three major axes, the Right Ascension
(RA) axis, Declination (DEC) axis, and the OTA line of site (LOS) axis.
This procedure concerns itself with the relationship of the major axes.
The DEC axis must be orthogonal, that is at perpendicular, with the RA
axis, and the OTA LOS axis must be coincide with the RA axis when the
OTA is at 90 degree DEC. If either of these relationships is compromised
then reduction in pointing accuracy will be the result.
Editor's Note: it is strongly recommended that you read through these procedures
until you are comfortable with the concepts of what you are trying to accomplish. Further, be sure to read the notes by Bruce
Johnston that correct
errors and provide additional information at critical points. Also see his webpage on GoTo Accuracy: <http://www.mapug-astronomy.net/ccdastro/goto-tests.htm> And
be sure to read the discussions on this Topical Archive page related to alignment accuracy.
Figure 1 - RA and DEC axes
Figure 2 - Line of site axis
Tools Needed:
*Laser Pen ($25 at office supply)
*Carpenter's square
*Equatorial Wedge
*3' X 3' X _" plywood
*(4) 1" X 4-40 machine screws
*Screw driver
*Set of hex wrenches
*Rubber mallet
*Utility knife
*Cedar shims
*Pen
*Paper
*Tape
