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loosen the Dec. lock knob (12). The telescope
should now be able to move freely on the Dec. axis.
Loosen the ring clamps on the tube rings (10) 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).
6. Position the telescope in the tube rings (10) so it
remains horizontal when you carefully let go with
both hands. This is the balance point for the optical
tube (11) with respect to the Dec. axis.
7. Retighten the ring clamps.
3.5. Polar Alignment of the Equatorial mount
Objects located in the sky appear to revolve around
the celestial pole. In northern latitudes, the North
Star (Polaris) is close to the pole. (In actual fact,
stars are essentially "fixed" in place and their
apparent motion is caused by the earth rotating
around its own axis.) Over a 24 hour period, stars
will perform a complete revolution around the pole,
generating concentric circles with the pole at their
center. By aligning the telescope's polar axis with
the celestial north pole (or with the celestial south
pole for observers located in the earth's southern
hemisphere), astronomic objects may be followed
(or tracked) by simply moving the telescope around
an axis, the polar axis.
If the telescope is reasonably aligned with the pole,
changing the instrument's declination using its
flexible control cable will consequently be of little
use – almost all the telescope motion required will
take place using the Right Ascension coordinates.
(If the telescope is perfectly aligned with the
pole—no declination change will be required to
follow stellar objects). For occasional visual
observations through the telescope, aligning the
telescope's polar axis by one or two degrees in
relation to the pole is more than enough. With this
level of aiming precision the telescope can achieve
precise tracking if the R.A. flexible control cable is
used while maintaining the objects within the
telescope's FOV for some 20 to 30 minutes.
To polar-align the telescope:
1. Level the equatorial mount by adjusting the
length of the three tripod legs (2).
2. Loosen the latitude adjustment knob (24) and tilt
the mount until the pointer on the latitude scale is
set at the latitude of your observing site. If you don’t
know your latitude, consult a geographical atlas or
search the internet. For example, if your latitude is
35° north, set the pointer to 35. Then retighten the
latitude knob. The latitude setting should not have
to be adjusted again unless you move to a different
viewing location some distance away.
3. Loosen the Dec. lock knob (12) and rotate the
telescope optical tube (11) until it is parallel with the
R.A. axis, as it is in Figure 1. The pointer on the
Dec. setting circle (13) should read 90°. Retighten
the Dec. lock knob.
4. Loosen the azimuth adjustment knob (23) on the
mount and rotate the mount so the telescope tube
(and R.A. axis) points roughly at Polaris. If you
cannot see Polaris directly from your observing site,
consult a compass and rotate the mount so the
telescope points north. Retighten the azimuth
adjustment knob.
Ursa minor
Polaris
Cassiopeia
Ursa major
Figure 3: Finding Polaris
The equatorial mount is now polar aligned.
From this point on in your observing session, you
should not make any further adjustments in the
azimuth or the latitude of the mount, nor should you
move the tripod. Doing so will undo the polar
alignment. The telescope should be moved only
about its R.A. and Dec. axes.