Orion ASTROVIEW 9822 - Manual (Page 6)

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from drifting out of your telescope’s field of view while you’re
observing.
This is accomplished by slowly rotating the telescope on its
right ascension (R.A.) axis, using only the R.A. slow-motion
cable. But first the R.A. axis of the mount must be aligned with
the Earth’s rotational (polar) axis – a process called polar
alignment.
Polar alignment
For Northern Hemisphere observers, approximate polar align-
ment is achieved by pointing the mount’s R.A. axis at the North
Star, or Polaris. It lies within 1° of the north celestial pole
(NCP), which is an extension of the Earth’s rotational axis out
into space. Stars in the Northern Hemisphere appear to
revolve around the NCP.
To find Polaris in the sky, look north and locate the pattern of
the Big Dipper (Figure 6). The two stars at the end of the “bowl”
of the Big Dipper point right to Polaris.
Observers in the Southern Hemisphere aren’t so fortunate to
have a bright star so near the south celestial pole (SCP). The
star Sigma Octantis lies about 1° from the SCP, but it is barely
visible with the naked eye (magnitude 5.5).
For general visual observation, an approximate polar align-
ment is sufficient.
1. Level the equatorial mount by adjusting the length of the
three tripod legs.
2. There are two latitude adjustment T-Bolts (see Figure 2);
loosen one T-Bolt while tightening the other. By doing this
you will adjust the latitude of the mount. Continue adjusting
the mount until the pointer on the latitude scale is set at the
latitude of your observing site. If you don’t know your lati-
tude, consult a geographical atlas to find it. For example, if
your latitude is 35° North, set the pointer to 35. The latitude
setting should not have to be adjusted again unless you
move to a different viewing location some distance away.
3. Loosen the Dec. lock lever and rotate the telescope’s opti-
cal tube until it is parallel with the R.A. axis, as it is in Figure
5. The pointer on the Dec. setting circle should read 90°.
Retighten the Dec. lock lever.
4. Move the tripod so the telescope tube and R.A. axis point
roughly at Polaris. If you cannot see Polaris directly from
your observing site, consult a compass and rotate the tri-
pod so the telescope points north. There is a label bearing
a large “N” at the base of the equatorial mount (Figure 7). It
should be facing north.
The equatorial mount is now polar aligned for casual observ-
ing. More precise polar alignment is recommended for astro-
photography.
From this point on in your observing session, you should not
make any further adjustments to the latitude of the mount, nor
should you move the tripod. Doing so will undo the polar align-
ment. The telescope should be moved only about its R.A. and
Dec. axes.
the Polar axis Finder scope
The AstroView Equatorial Mount features a polar axis finder
scope housed inside the R.A. axis of the mount (see Figure 3).
When properly aligned and used, it makes accurate polar
alignment quick and easy to do. Alignment of the polar finder
need only be done once, unless it gets bumped or otherwise
shifts its position.
Remove the round cover cap from the front opening in the
R.A. axis of the mount. Look through the polar finder at a dis-
tant object during the day. Focus the polar finder so that the
images and reticle are sharp by rotating the eyepiece end of
the finder. Notice that the reticle pattern consists of a crosshair
with a circle around the middle. On the circumference of this
circle is a tiny circle; this is where Polaris will be placed for
accurate polar alignment once the finder is properly aligned.
Alignment of the polar finder is best done during the day,
before going out into the field at night.
Figure 6. To find Polaris in the night sky, look north and find the
Big Dipper. Extend an imaginary line from the two "Pointer Stars" in
the bowl of the Big Dipper. Go about five times the distance
between those stars and you'll reach Polaris, which lies within 1° of
the north celestial pole (NCP).
Big Dipper
(in Ursa Major)
Little Dipper
(in Ursa Minor)
N.C.P.
Pointer
Stars
Polaris
Cassiopeia
Figure 7. For polar alignment, position the tripod so that the “N”
label at the base of the mount faces north. The two azimuth fine
adjustment knobs above it are used to make small adjustments to
the mount’s azimuth position.
Azimuth
fine adjustment
knobs
Tripod
attachment
knob