Meade EXT90 Instruction Manual page 52

"locked" positions, use the Arrow keys to move the
optical tube.
+
North
Celestial
Pole
North tripod leg
Figure 20: Example of Polar Alignment. Note that the face
of the tilt-plate points north
Note: For most astronomical observing requirements,
approximate settings of the telescope's latitude
and North-pointing tripod leg (Steps #5 and #6) are
acceptable. Do not allow undue attention to precise
equatorial mounting of the telescope to interfere with
your enjoyment of the instrument.
Using an Equatorially Mounted Telescope
Once your telescope is equatorially mounted, the
telescope motor drive will keep a celestial object in the
telescope eyepiece's field of view.
Caution: Do not move the tripod or adjust the latitude
setting while observing or the mounting alignment will
be lost. The telescope's motor drive disengages when
the Horizontal and the Vertical lock levers are unlocked
and re-engages when the levers are relocked.
AutoStar Polar Alignment
+
North
Celestial
Pole
Figure 21: Example of Polar Alignment. Note that the
face of the tilt-plate points north
AutoStar provides three different (manual) methods for
polar alignment: Easy, One-Star and Two-Star.
2
Easy Polar Alignment
Two alignment stars are chosen by AutoStar based on
the date, time and location. First, choose "Polar" from
the "Setup: Telescope: Mount" menu. The rest of the
procedure is identical to the Alt/Az Easy (Two-Star)
Align, page 11.
One-Star Polar Alignment
Polar One-Star Alignment requires some knowledge of
the night sky. AutoStar provides a database of bright
stars and one star from this database is chosen by the
observer for alignment. Polaris is chosen by AutoStar.
First, choose "Polar" from the "Setup: Telescope: Mount"
menu. The rest of the procedure is almost identical to
the Alt/Az One Star Alt/Az Alignment, page 41, except
that AutoStar prompts you to point the telescope at
Polaris and center it in the telescope eyepiece.
Two-Star Polar Alignment
Polar Two-Star Alignment requires some knowledge of
the night sky. AutoStar provides a database of bright
stars and two stars from this database are chosen by
the observer for alignment. First, choose "Polar" from
the "Setup: Telescope: Mount" menu. The rest of the
procedure is almost identical to the Alt/Az Two Star Alt/
Az Alignment, page 39.
Locating the Celestial Pole
To get basic bearings at an observing location, take
note of where the Sun rises (East) and sets (West) each
day. After the site is dark, face North by pointing your
left shoulder toward where the Sun sets. To precisely
point at the pole, find the North Star (Polaris) by using
the Big Dipper as a guide (Fig. 22).
Important Note: For almost all astronomical observing
requirements, approximate settings of the telescope's
Latitude control bar
latitude and Polar axis are acceptable. Do not allow
undue attention to precise Polar Alignment of the
telescope to interfere with your basic enjoyment of the
instrument.
Figure 22: Locating Polaris
Little Dipper
Polaris
Big Dipper
Cassiopeia