Sky-Watcher EQ2 MOUNT - Manual (Page 17)

17
Pointing to the NCP
For the following examples, it is
assumed that the observing site is in
the Northern Hemisphere. In the first
case (Fig.m2), the optical tube is
pointing to the NCP. This is its
probable position following the
polar-alignment step. Since the
telescope is pointing parallel to the
polar axis, it still points to the NCP as it
is rotated around that axis
counter-clockwise, (Fig.m1) or
clockwise (Fig.m3).
Pointing toward the western or
eastern horizon
Now, consider pointing the telescope
to the western (Fig.n1) or eastern
(Fig.n2) horizon. If the counterweight
is pointing North, the telescope can
be swivelled from one horizon to the
other around the Dec axis in an arc
that passes through the NCP (any Dec
arc will pass through the NCP if the
mount is polar-aligned). It can be
seen then that if the optical tube
needs to be pointed at an object
north or south of this arc, it has to be
also rotated around the R.A axis.
Fig.m
1.
2.
3.
Celestial Pole
+
Fig.n
Telescope pointing West
Counterweight pointing North
Telescope pointing East
Counterweight pointing North
+
Celestial
Pole
1.
2.
Rotation of the Dec. axis
Rotation of the R.A. axis