Axis Alignment Method #2 - Meade LXD 75 Instruction Manual

Fig. 44: A. Elevation Alignment;
B. Attitude Alignment.
4. Autostar then chooses three stars from its database to align upon. When the
telescope slews to a star for alignment, it may not appear in the field of view in the
eyepiece. Use the Arrow keys to move the telescope until the star is visible and
centered in the eyepiece. The alignment star should be easily recognized and be
the brightest star in the area of the sky where the telescope is pointing. See
ONE'S THE ALIGNMENT STAR
centered, press ENTER. Repeat the procedure for the second and third alignment
stars.
Note: Autostar locates alignment stars based on the date, time, and
location entered. The alignment stars may change from night to night. All
that is required is for the observer to center the selected star in the
eyepiece when prompted.
Method 2: Axis Alignment Procedures
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 ade-
quately without making any adjustments, but performing one of the following align-
ment 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.
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 tar-
gets. 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.
Loosen the R.A. Lock (33, Fig. 1d) and the Dec. Lock (17, Fig. 1d). Point the tube
2.
so that the tripod leg below the Fine Azimuth Control Knobs (27, Fig. 1c) approx-
imately faces North (or South in the Southern Hemisphere). Retighten the Dec.
Lock. Move the counterweight shaft and mount so that it is parallel to the horizon.
This is position A. See Fig. 45. Retighten the R.A. Lock.
3. If using a Schmidt Newtonian model, rotate the optical tube (you will need to
loosen the cradle ring lock knobs (13, Fig. 1a) to do so) to make sure the focuser
extends horizontally from the optical tube while in position A and do not rotate the
tube for the remainder of the alignment procedure.
If using a refractor model, use the diagonal assembly to rotate the eyepiece
during testing. However, be careful that the diagonal is placed flush against the
focuser and tightened in place using the thumbscrews. It is important that the
diagonal does not slip during the procedure.
4. Adjust the tripod legs, polar axis altitude and/or polar axis azimuth so that the
wide, horizontal object you have chosen as a target is positioned across the mid-
dle of the eyepiece.
Procedure #1: Step 4 Step 5
, page 18, for more information. When the star is
Step 6
WHICH
Step 7
5 3