rotate freely about the R.A. axis. Rotate it until the coun- terweight shaft is parallel to the ground (i.e., horizontal).
2.Now loosen the counterweight locking thumbscrew and slide the weight along the shaft until it exactly counterbal- ances the telescope. (Figure 2a) That’s the point at which the shaft remains horizontal even when you let go with both hands (Figure 2b).
3.Retighten the counterweight locking thumbscrew. The tel- escope is now balanced on the R.A. axis.
4.To balance the telescope on the Dec. axis, first tighten the R.A. lock knob, with the counterweight shaft still in the hor- izontal position.
5.With one hand on the telescope optical tube, loosen the Dec. lock knob (Figure 2c). The telescope should now be able to rotate freely about the Dec. axis. Loosen the tube ring clamps a few turns, until you can slide the telescope tube forward and back inside the rings (this can be aided by using a slight twisting motion on the optical tube while you push or pull on it) (Figure 2d).
6.Position the telescope in the mounting rings so it remains horizontal when you carefully let go with both hands. This is the balance point for the optical tube with respect to the Dec. axis (Figure 2e).
7.Retighten the tube ring clamps.
The telescope is now balanced on both axes. Now when you loosen the lock knob on one or both axes and manually point the telescope, it should move without resistance and should not drift from where you point it.
4. Aligning the Finder Scope
A finder scope has a wide field of view to facilitate the loca- tion of objects for subsequent viewing through the main telescope, which has a much narrower field of view. The find- er scope and the main telescope must be aligned so they point to exactly the same spot in the sky.
Alignment is easiest to do in daylight hours. First, insert the lowest-power (25mm) eyepiece into the star diagonal. Then loosen the R.A. and Dec. lock knobs so the telescope can be moved freely.
Point the main telescope at a discrete object such as the top of a telephone pole or a street sign that is at least a quarter- mile away. Move the telescope so the target object appears in the very center of the field of view when you look into the eye- piece. Now tighten the R.A. and Dec. lock knobs. Use the slow-motion control knobs to re-center the object in the field of view, if it moved off-center when you tightened the lock knobs.
Now look through the finder scope. Is the object centered in the finder scope’s field of view, (i.e., at the intersection of the crosshairs)? If not, hopefully it will be visible somewhere in the field of view, so that only fine adjustment of the finder scope alignment screws will be needed to center it on the crosshairs. Otherwise you’ll have to make coarser adjust- ments to the alignment screws to redirect the aim of the finder
scope. Make sure the knurled lock nut on each alignment screw is loosened before making any adjustments.
Once the target object is centered on the crosshairs of the finder scope, look again in the main telescope’s eyepiece and see if it is still centered there as well. If it isn’t, repeat the entire process, making sure not to move the main telescope while adjusting the alignment of the finder scope.
When the target object is centered on the crosshairs of the finder scope and in the telescope’s eyepiece, tighten the knurled lock nuts on the alignment screws to lock the finder scope into position. The finder scope is now aligned and ready to be used for an observing session. The finder scope and bracket can be removed from the dovetail for storage, and then re-installed without changing the finder scope’s alignment.
Note that the image seen through the finder scope appears upside down. This is normal for astronomical finder scopes.
5.Setting Up and Using the Equatorial Mount
When you look at the night sky, you no doubt have noticed that the stars appear to move slowly from east to west over time. That apparent motion is caused by the Earth’s rotation (from west to east). An equatorial mount (Figure 3) is designed to compensate for that motion, allowing you to eas- ily “track” the movement of astronomical objects, thereby keeping them from drifting out of the telescope’s field of view while you’re observing.
This is accomplished by slowly rotating the telescope on its right ascension (polar) axis, using only the R.A. slow-motion cable. But first the R.A. axis of the mount must be aligned with the Earth’s rotational (polar) axis—a process called polar alignment.
Polar Alignment
For Northern Hemisphere observers, approximate polar alignment is achieved by pointing the mount’s R.A. axis at the North Star, or Polaris. It lies within 1 degree of the north celestial pole (NCP), which is an extension of the Earth’s rota- tional axis out into space. Stars in the Northern Hemisphere appear to revolve around Polaris.
To find Polaris in the sky, look north and locate the pattern of the Big Dipper (Figure 4). The two stars at the end of the “bowl” of the Big Dipper point right to Polaris.
Observers in the Southern Hemisphere aren’t so fortunate to have a bright star so near the south celestial pole (SCP). The star Sigma Octantis lies about 1 degree from the SCP, but it is barely visible with the naked eye (magnitude 5.5).
For general visual observation, an approximate polar align- ment is sufficient:
1.Level the equatorial mount by adjusting the length of the three tripod legs.
2.Loosen the latitude locking t-bolt. Turn the latitude adjust- ing t-bolt and tilt the mount until the pointer on the latitude
