Page 42 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

EQUATORIAL

MOUNTS

PART 1 SETTING UP

EQUATORIAL MOUNTS LET YOU Putting your telescope on an equatorial mount enables you to follow
TRACK AN OBJECT AS IT MOVES stars as they continue their steady progress across the night sky. The
mount may look complex, but it really doesn’t take long to master.
ACROSS THE NIGHT SKY Over the next six pages, we’re breaking down everything about
these mounts into easy-to-follow steps, starting with putting them
together. We’re using an EQ3 mount, but the techniques will work for
other types, too.

MOUNT HEAD Tube rings Tube ring
An equatorial mount is made up of a tripod These go round the telescope locks
to fi x it to the plate, which
and a mount head, which holds the telescope fi xes to the mount head Make sure
these are
and moves it about on two axes, one called screwed in
right ascension (RA) and the other called RA slow tightly to hold
the tube fi rm
motion control
declination (Dec.) With the axis locks
tightened, this is used to
fi ne-tune exactly where Declination
Dec. slow Right ascension the scope is pointing (Dec.) axis
motion control (RA) axis lock lock
Loosening the RA Azimuth lock
and Dec. axis locks Moves the mount
lets the scope turn parallel to the horizon
freely to a new for setting it up. Not
target. Tighten them used to fi nd targets
up again when
you’re close Counterweights
These balance the
weight of the scope

Polarscope fi tting RA setting
The mount’s RA axis circle
may be hollow to fi t Scales for dialling Dovetail
an optional small in the coordinates mounting plate
polarscope in, which of celestial targets. This is where the
will help you set it up They’re useful, but tube, in its rings, is
not essential held in the mount

Altitude setting
Tilts the mount Dec. setting
ALL PHOTOS: PAUL WHITFIELD same angle as circle
and scope to the
your latitude.
Not used to
fi nd targets

42 skyatnightmagazine.com 2012