Page 80 - BBC Sky at Night - September 2017 UK

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SKILLS 80 The Guide
82 How to
84 Image Processing
87 Scope Doctor
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Getting to grips with altaz mounts

What altaz mounts are, how they work and why ‘simple’ doesn’t always mean ‘bad’

ltaz mounts can be regarded as
< The typical elements of an altaz
the oldest form of mounting
mount; the one you see here is the
for a telescope. They have two Celestron NexStar Evolution 8
Aaxes of rotation, one level with Optics
the horizon and the other moves in
elevation (altitude). ‘Alt’ derives from
altitude and ‘Az’ from azimuth, the latter
being the position measured from
north, usually through east along the
horizon. Last month we looked at
equatorial mounts, which are technically
Single-arm fork
altaz mounts tilted so that one axis is
aligned with Earth’s polar axis.
Unlike equatorial mounts, altaz systems
don’t track the stars, but they are quick
and easy to set up. Unpowered versions
Counterweights
require no alignment whatsoever. The
Ports
simplest forms are push-pull variants
and Dobsonians (we’ll cover this second
variant in detail next month), where you
either manually move the scope and point
it at your target or have simple slow- Go-To hand controller
motion controls to move the mount.

Growing sophistication Tripod
With the advent of computerised,
motorised ‘Go-To’ systems, altaz mounts
have become more sophisticated. Some
now support Go-To, and can track targets
in the night sky once an alignment
process has been completed. Initially
this technology was limited to high-
WWW.THESECRETSTUDIO.NET X 3, TRACK THE STARS now widely available, for example the
end, high-cost systems, but no longer.
Single- and dual-arm altaz mounts are
Meade ETX, Celestron NexStar and
Sky-Watcher SkyMax series. iOptron
has also launched an unusual take on
the design with the iOptron AZ Pro,
where the mount has been designed as
a cube. Such systems have helped bring
Go-To technology to a wider audience

skyatnightmagazine.com 2017