14
2. Loosen the latitude lock T-bolt (29). Turn the latitude adjust-
ment T-bolt (30) and tilt the mount until the pointer on the
latitude 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 lock 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 (25) and rotate the telescope
optical tube (1) until it is parallel with the R.A. axis, as it is
in Figure 1. The pointer on the Dec. setting circle (22)
should read 90°. Retighten the Dec. lock lever.
4. Loosen the azimuth lock knob (31) at the base of the
equatorial mount (5) and rotate the mount so the telescope
tube (and R.A. axis) points roughly at Polaris. If you cannot
see Polaris directly from your observing site, consult a
compass and rotate the mount so the telescope points
North. Retighten the azimuth lock knob.
The equatorial mount is now polar aligned.
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 tripod.
Doing so will undo the polar alignment. The telescope
should be moved only about its R.A. and Dec. axes.
use of the r.a. and Dec.
slow-Motion control cables
The R.A. and Dec. slow-motion control cables (8,9) allow fine
adjustment of the telescope’s position to center objects within
the field of view. Before you can use the cables, you must
manually “slew” the mount to point the telescope in the vicinity
of the desired target. Do this by loosening the R.A. and Dec.
lock knobs (23,25) and moving the telescope about the
mount’s R.A. and Dec. axes. Once the telescope is pointed
somewhere close to the object to be viewed, retighten the
mount’s R.A. and Dec. lock knobs.
The object should now be visible somewhere in the EZ Finder
II (4). If it isn’t, use the slow-motion controls to scan the sur-
rounding area of sky. When the object is visible in the EZ
Finder II, use the slow-motion controls to center it. Now, look
in the telescope’s eyepiece. If the EZ Finder II is properly
aligned, the object should be visible somewhere in the field of
view. Once the object is visible in the eyepiece, use the slow-
motion controls to center it in the field of view.
The Dec. slow-motion control cable (9) can move the tele-
scope a maximum of 25°. This is because the Dec. slow-
motion mechanism has a limited range of mechanical travel.
(The R.A. slow-motion mechanism has no limit to its amount
of travel.) If you can no longer rotate the Dec. control cable in
a desired direction, you have reached the end of travel, and
the slow-motion mechanism must be reset. This is done by
first rotating the control cable several turns in the opposite
direction from which it was originally being turned. Then, man-
ually slew the telescope closer to the object you wish to
observe (remember to first loosen the Dec. lock knob (25)).
You should now be able to use the Dec. slow-motion control
cable again to fine adjust the telescope’s position.
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 cable clockwise. The Dec. slow-
motion control cable is not needed for tracking. Objects will
appear to move faster at higher magnifications, because the
field of view is narrower.
optional Electronic Drives for
automatic tracking
An optional DC electronic drive can be mounted on the R.A. axis
of the 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 cable (8).
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 mount’s R.A. setting circle (24) is scaled in hours, from 1
through 24, with small marks in between representing 10-min-
ute increments. The numbers closest to the R.A. axis gear
apply to viewing in the Southern Hemisphere, while the num-
bers above them apply to viewing in the Northern
Hemisphere.
The Dec. setting circle (22) is scaled in degrees, with each
mark representing 2.5° increments. Values of Dec. coordi-
nates range from +90° to -90°. The 0° mark indicates the
celestial equator. When the telescope is pointed north of the
celestial equator, values of the Dec. setting circle are positive,
while when the telescope is pointed south of the celestial
equator, values of the Dec. setting circle are negative.
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 (there are 70 arc-
minutes in 1 degree of declination).
Before you can use the setting circles to locate objects, the
mount must be correctly polar aligned, and the R.A. setting
circle must be calibrated. The Dec. setting circle has been per-
manently calibrated at the factory, and should read 90° when-
ever the telescope optical tube is parallel with the R.A. axis.