the principle of compass direction
(azimuth) and elevation (altitude),
effectively moving the tripod up and
down, or left and right. To keep an
object in view over a period of time
both controls need to be adjusted.
The German equatorial mount,
also known as an equatorial mount
or GEM, is a much more complex
mounting system that takes into
consideration the movement of
stars around the celestial pole.
Setting up the equatorial mount can
be complicated as one axis of the
mount needs to point to the polar
star. Once properly aligned the stars
can be tracked just by using a single
control. This control can be driven
with a motor enabling the precise
tracking of stars throughout the
night. This type of mount is ideal for
astro photographers as it keeps
the aspect and relationship of
the stellar objects aligned
over time.
Another type of mount
available is a Dobsonian. This
is actually a variant of the AltAz mount, but with the base
actually on the ground
with a swivel plate.
The telescope
drops onto
this and
there
are
friction
plates to
control the elevation.
This type of telescope
looks like a canon.
One advantage of a
‘Dob’ is that it can
be very large, but
still controllable by
hand.
Going HighTech
So
far
everything
has been
‘low tech’
in as much as it is pure physics and
engineering. To use the telescope you
need to understand the movement
of the stars and be able to find and
hone in on the objects that you
want to view. Wouldn’t it be nice if
you could press a few buttons and
the telescope would move to your
area of interest and keep it in view
as the earth rotates?
The advent of the GOTO mount
has achieved this. To the purists this
is sacrilege, but for observers with
limited time and experience it is a
boon. The technology does make
us lazy and prevents us learning the
full majesty of the night skies, but on
the other hand it opens up a new
frontier to those who do not have
the time or the inclination to learn
the constellations.
The GOTO mount needs to be
calibrated each time it \