8
T-bolt before tightening the other.) If you don’t know your
location’s latitude, you can look it up on the internet. For
example, if your latitude is 35° North, set the pointer to 35.
Then retighten the latitude lock knob. The latitude setting
should not have to be adjusted again unless you move to a
different viewing location some distance away.
4. Next, loosen the mount attachment knob (see
Figure 6
) just
enough to allow you to rotate the mount in azimuth. Then
rotate the mount by hand so the R.A. axis points rough-
ly at Polaris (
Figure 6
). If you cannot see Polaris directly
from your observing site, consult a compass and rotate the
mount so the telescope points North. Then retighten the
mount attachment knob.
The equatorial mount is now (roughly) polar aligned. From this
point on in your observing session, you should not make any
further adjustments to the azimuth or the latitude of the mount,
nor should you move the tripod. Doing so will ruin the polar
alignment. The telescope should henceforth be moved only
about its R.A. and Dec. axes.
VII. Using the R.A. and Dec.
Slow-Motion Control Cables
The R.A. and Dec. slow-motion control cables (see
Figure 6
)
allow fine adjustment of the mount’s position to center objects
within the telescope’s field of view. Before using the cables,
manually “slew” the mount to point the telescope in the vicinity
of the desired target. Do this by loosening the R.A. and Dec.
lock knobs and moving the telescope about the mount’s R.A.
and Dec. axes. Once the telescope is pointed somewhere
close to the object to be viewed, retighten the mount’s R.A.
and Dec. lock knobs.
The object should now be visible somewhere in the field of
view of the EZ Finder II. If it isn’t, use the slow-motion controls
to scan the surrounding area of sky. Note: when using the slow
motion cables, the R.A. and Dec lock knobs should be tight-
ened, not loose. When the object is visible in the finder scope,
use the slow-motion controls to center it. Now, look in the tele-
scope’s eyepiece (start with the low power 25mm eyepiece)
and use the slow-motion controls to center it in the eyepiece.
The R.A. slow motion cable can turn the mount’s R.A. axis a
full 360 degrees. However, the Dec. slow-motion cable has a
limited range of about 25 degrees. If you reach the end of the
range of motion – and you cannot turn the knob further – you
should reverse direction by 10 degrees or so, then release the
Dec. lock knob and move the telescope by hand back to about
where it was pointed before the slow-motion cable stopped
turning. Now you should be able to use the slow motion cable
again for fine pointing in either direction.
VIII. Tracking Celestial
Objects
When you observe a celestial object through the telescope,
you’ll see it drift slowly across the field of view. To keep it in the
field, assuming the equatorial mount is polar aligned, just turn
the R.A. slow-motion control cable counterclockwise to track.
The Dec. slow-motion control cable is not needed for tracking.
Objects will appear to move faster at higher magnifications,
because the field of view is narrower.
Optional Electronic Drive for Automatic Tracking
An optional DC electronic drive is available for the SpaceProbe
130mm reflector. This battery-operated drive provides auto-
mated, hands-free tracking. Objects will then remain stationary
in the field of view without any manual adjustment of the R.A.
slow-motion control cable.
Understanding the Setting Circles
The two setting circles on an equatorial mount enable you to
locate celestial objects by their “celestial coordinates”. Every
object resides in a specific location on the “celestial sphere”.
That location is denoted by two numbers: its right ascension
(R.A.) and declination (Dec.). In the same way, every location
on Earth can be described by its longitude and latitude. R.A.
is similar to longitude on Earth, and Dec. is similar to latitude.
The R.A. and Dec. values for celestial objects can be found in
any star atlas or online planetarium app.
On the SpaceProbe 130mm, the R.A. setting circle is scaled
in hours, from 1 through 24, with small marks in between rep-
resenting 10-minute increments (
Figure 14
). The numbers
at the base of the setting circle scale apply to the Northern
Hemisphere while the numbers above them apply to viewing in
the Southern Hemisphere.
The Dec. setting circle is denoted in degrees, with each main
mark representing 10° increments (
Figure 14
). Values of Dec.
coordinates range from +90° to -90°. The 0° mark indicates the
celestial equator. For this mount, the number scale goes to 90 on
Figure 14.
The R.A. and Dec. setting circles allow you to locate
an object by its R.A. and Dec. coordinates.
Dec. setting
circle
R. A. setting
circle
