8
torial mount). Focus the polar finder by rotating its eye-
piece. Now, sight Polaris in the polar axis finder scope. If
you have followed the approximate polar alignment pro-
cedure accurately, Polaris will probably be within the field
of view. If it is not, move the tripod left-to-right, and adjust
the latitude up-and-down until Polaris is somewhere with-
in the field of view of the polar axis finder scope.
3. Shine a red flashlight down the front end of the polar find-
er to illuminate the reticle within the field of view. Make
sure the flashlight shines in at an angle, so as not to block
the polar finder’s field of view. It may be helpful to have a
friend hold the flashlight while you look through the polar
finder. Note the constellations Cassiopeia and Ursa Major
(the Big Dipper) in the reticle (ignore the constellation
Octans, as this is provided for Southern Hemisphere
observers). They do not appear to scale, but they indicate
the general positions of Cassiopeia and Ursa Major rela-
tive to Polaris and the north celestial pole (which is
indicated by the cross at the center of the reticle). Next,
the reticle must be rotated so the constellations depicted
match their current orientation in the sky when viewed
with the naked eye. To do this, release the R.A. lock lever
and rotate the main telescope about the R.A. axis until the
reticle is oriented with the sky. You may need to reposition
the telescope about the declination axis so the telescope
does not bump the mount. Once the reticle is correctly ori-
ented, use the R.A. lock lever to secure the main
telescope’s position.
4. Now, use the azimuth and latitude adjustment knobs on
the mount to position the star Polaris inside the tiny circle
marked “Polaris” in the polar finder’s reticle. You must first
release the latitude lock lever and loosen the bolt that con-
nects the equatorial head to the tripod (underneath the
equatorial mount). Once Polaris is properly positioned
within the reticle, lock the latitude lock lever and retighten
the bolt that connects the equatorial head to the tripod.
You are now precisely polar-aligned.
If you do not have a clear view of Polaris from your observ-
ing site, then you will not be able to use the polar axis finder
scope to precisely polar-align the telescope.
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
An optional DC motor drive (Orion AccuTrack SVD, #7825)
can be mounted on the R.A. axis of the SkyView Deluxe
equatorial mount to provide hands-free tracking. Objects will
then remain stationary in the field of view without any manu-
al adjustment of the R.A. slow-motion control.
Understanding the Setting Circles
The setting circles on an equatorial mount enable you to
locate celestial objects by their “celestial coordinates.” Every
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.
The R.A. setting circle is scaled in hours, from 1 through 24,
with small hash marks in between representing 10 minute
increments (there are 60 minutes in 1 hour of R.A.). The Dec.
setting circle is scaled in degrees (there are 60 arc-minutes
in 1 degree of declination),with hash marks representing 2
degree increments.
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).
Before you can use the setting circles to locate objects, the
mount must be precisely polar aligned, and the setting circles
must be calibrated.
Calibrating the Declination Setting Circle
1. Loosen the Dec. lock lever and position the telescope as
accurately as possible in declination so it is parallel to the
R.A. axis of the equatorial mount. Re-tighten the lock lever.
2. Rotate the Dec. setting circle until the pointer reads exactly 90°.
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 levers on the equatorial
mount, so the telescope optical tube can move freely.
3. Point the telescope at the bright star near the celestial
equator whose coordinates you know. This information can
be taken from any star chart. Center the star in the tele-
scope’s field of view. Lock the R.A. and Dec. lock levers.
4. Rotate the R.A. setting circle so the pointer indicates the
R.A. listed for that object 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 lever and rotate the telescope until
the Dec. value from the star atlas matches the reading on
the Dec. setting circle. Retighten the lock lever.
2. Loosen the R.A. lock lever 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 lever.
