Orion SKYWATCHER 9086 - Manual (Page 6)

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scale is set at the latitude of your observing site. If you
don’t know your latitude, consult a geographical atlas to
find it. For example, if your latitude is 35° North, set the
pointer to +35. Then retighten the latitude locking t-bolt.
The latitude setting should not have to be adjusted again
unless you move to a different viewing location some dis-
tance away.
3. Loosen the Dec. lock knob and rotate the telescope opti-
cal tube until it is parallel with the R.A. axis. The pointer on
the Dec. setting circle should read 90°. Retighten the Dec.
lock knob.
4. Loosen the azimuth adjustment knob and rotate the entire
equatorial mount left-to-right so the telescope tube (and
R.A. axis) points roughly at Polaris. If you cannot see
Polaris directly from your observing site, consult a com-
pass and rotate the equatorial mount so the telescope
points North. Retighten the azimuth adjustment knob.
The equatorial mount is now approximately polar-aligned for
casual observing. More precise polar alignment is required for
astrophotography. Several methods exist and are described in
many amateur astronomy reference books and astronomy
magazines.
Note: From this point on in your observing session, you
should not make any further adjustments in the azimuth
or the latitude of the mount, nor should you move the tri-
pod. Doing so will undo the polar alignment.The telescope
should be moved only about its R.A. and Dec. axes.
Tracking Celestial Objects
When you observe a celestial object through the telescope,
you’ll see it drift slowly across the field of view. To keep it in
the field, if your equatorial mount is polar-aligned, just turn the
R.A. slow-motion control. The Dec. slow-motion control is not
needed for tracking. Objects will appear to move faster at
higher magnifications, because the field of view is narrower.
Optional Motor Drives for Automatic Tracking
and Astrophotography
An optional DC motor drive (#7827) can be mounted on the
R.A. axis of the Skywatcher’s equatorial mount to provide
hands-free tracking. Objects will then remain stationary in the
field of view without any manual adjustment of the R.A. slow-
motion control. The motor drive is necessary for
astrophotography.
Understanding the Setting Circles
The setting circles on an equatorial mount enable you to
locate celestial objects by their “celestial coordinates.” Every
astronomical object resides in a specific location on the
“celestial sphere.” That location is denoted by two numbers:
its right ascension (R.A.) and declination (Dec.). In the same
way, every location on Earth can be described by its longitude
and latitude. R.A. is similar to longitude on Earth, and Dec. is
similar to latitude. The R.A. and Dec. values for celestial
objects can be found in any star atlas or star catalog.
So, the coordinates for the Orion Nebula listed in a star atlas
will look like this:
R.A. 5h 35.4m Dec. -5° 27'
That’s 5 hours and 35.4 minutes in right ascension, and -5
degrees and 27 arc-minutes in declination (the negative sign
denotes south of the celestial equator). There are 60 minutes
in 1 hour of R.A. and there are 60 arc-minutes in 1 degree of
declination.
The telescope’s R.A. setting circle is scaled in hours, from 1
through 24, with small hash marks in between representing
10-minute increments. The lower set of numbers (closest to
the plastic R.A. gear cover) apply to viewing in the Northern
Hemisphere, while the numbers above them apply to viewing
in the Southern Hemisphere. The Dec. setting circle is scaled
in degrees.
Before you can use the setting circles to locate objects, the
mount must be polar aligned, and the setting circles must be
calibrated. The declination setting circle was calibrated at the
factory, and should read 90° when the telescope optical tube
is pointing exactly along the polar axis.
Calibrating the Right Ascension Setting Circle
1. Identify a bright star near the celestial equator and look up
its coordinates in a star atlas.
2. Loosen the R.A. and Dec. lock knobs on the equatorial
mount, so the telescope optical tube can move freely.
3. Point the telescope at the bright star near the celestial equa-
tor whose coordinates you know. Center the star in the
telescope’s field of view. Lock the R.A. and Dec. lock knobs.
4. Rotate the R.A. setting circle so the pointer indicates the
R.A. listed for the bright star in the star atlas.
Finding Objects With the Setting Circles
Now that both setting circles are calibrated, look up in a star
atlas the coordinates of an object you wish to view.
1. Loosen the Dec. lock knob and rotate the telescope until
the Dec. value from the star atlas matches the reading on
the Dec. setting circle. Retighten the lock knob. Note: If the
telescope is aimed south and the Dec. setting circle point-
er passes the 0° indicator, the value on the Dec. setting
circle becomes a negative number.
2. Loosen the R.A. lock knob and rotate the telescope until
the R.A. value from the star atlas matches the reading on
the R.A. setting circle. Retighten the lock knob.
Most setting circles are not accurate enough to put an object
dead-center in your finder scope’s field of view, but they’ll get
you close, assuming the equatorial mount is accurately polar-
aligned. The R.A. setting circle should be re-calibrated every
time you wish to locate a new object. Do so by calibrating the
setting circle for the centered object before moving on to the
next one.
Confused About Pointing the Telescope?
Beginners occasionally experience some confusion about
how to point the telescope overhead or in other directions. In