Orion SPACEPROBE 130ST EQ - Manual (Page 9)

scale that is on the eastern half of the Dec. setting circle.
Retighten the Dec. lock knob.
2. Loosen the R.A. lock knob and rotate the telescope until
the R.A. value from the star atlas matches the reading on
the R.A. setting circle. Retighten the lock knob.
Most setting circles are not accurate enough to put an object
dead-center in the telescope’s eyepiece, but they should
place the object somewhere within the field of view of the
finder scope, assuming the equatorial mount is accurately
polar aligned. Use the slow-motion controls to center the
object in the finder scope, and it should appear in the tele-
scope’s field of view.
The R.A. setting circle must be re-calibrated every time you
wish to locate a new object. Do so by calibrating the setting
circle for the centered object before moving on to the next one.
Confused About Pointing the telescope?
Beginners occasionally experience some confusion about
how to point the telescope overhead or in other directions. In
Figure 1 the telescope is pointed north, as it would be during
polar alignment. The counterweight shaft is oriented down-
ward. But it will not look like that when the telescope is point-
ed in other directions. Let’s say you want to view an object
that is directly overhead, at the zenith. how do you do it?
One thing you DO NOT do is make any adjustment to the
latitude adjustment T-bolt. That will nullify the mount’s polar
alignment. Remember, once the mount is polar aligned, the
telescope should be moved only on the R.A. and Dec. axes.
To point the scope overhead, first loosen the R.A. lock knob
and rotate the telescope on the R.A. axis until the coun-
terweight shaft is horizontal (parallel to the ground). Then
loosen the Dec. lock knob and rotate the telescope until it
is pointing straight overhead. The counterweight shaft is still
horizontal. Then retighten both lock knobs.
Similarly, to point the telescope directly south, the counter-
weight shaft should again be horizontal. Then you simply
rotate the scope on the Dec. axis until it points in the south
direction.
What if you need to aim the telescope directly north, but at
an object that is nearer to the horizon than Polaris? You can’t
do it with the counterweight down as pictured in Figure 1.
Again, you have to rotate the scope in R.A. so the counter-
weight shaft is positioned horizontally. Then rotate the scope
in Dec. so it points to where you want it near the horizon.
To point the telescope to the east or west, or in other direc-
tions, you rotate the telescope on its R.A. and Dec. axes.
Depending on the altitude of the object you want to observe,
the counterweight shaft will be oriented somewhere between
vertical and horizontal.
Figure 7 illustrates how the telescope will look pointed at
the four cardinal directions — north, south, east, and west
The key things to remember when pointing the telescope is
that a) you only move it in R.A. and Dec., not in azimuth or
latitude (altitude), and b) the counterweight and shaft will not
always appear as it does in Figure 1. In fact, it almost never
will!
6. Collimating the Optics
(Aligning the Mirrors)
Collimating is the process of adjusting the mirrors so they
are aligned with one another. Your telescope’s optics were
aligned at the factory, and should not need much adjustment
unless the telescope is handled roughly. Accurate mirror
alignment is important to ensure the peak performance of
your telescope, so it should be checked regularly. Collimating
is relatively easy to do and can be done in daylight.
To check collimation, remove the eyepiece and look down
the focuser drawtube. You should see the secondary mirror
centered in the drawtube, as well as the reflection of the pri-
mary mirror centered in the secondary mirror, and the reflec-
9
Figure 7. This illustration shows the telescope pointed in the four
cardinal directions: (a) north, (b) south, (c) east, (d) west. Note that
the tripod and mount have not been moved; only the telescope tube
has been moved on the R.A. and Dec. axes.
a. b.
c. d.