Setting Up And Using The Equatorial Mount - Orion SpaceProbe 3 EQ Instruction Manual

With your eyes positioned at a comfortable distance, look
through the back of the reflex sight with both eyes open to see
the red dot. The intensity of the dot can be adjusted by turning
the power knob. For best results when stargazing, use the
dimmest possible setting that allows you to see the dot with-
out difficulty. Typically, a dim setting is used under dark skies
and a bright setting is used under light-polluted skies or in
daylight.
At the end of your observing session, be sure to turn the
power knob counterclockwise until it clicks off. When the two
white dots on the EZ Finder II's rail and power knob are lined
up, the EZ Finder II is turned off.
Aligning the EZ Finder II
When the EZ Finder II is properly aligned with the telescope,
an object that is centered on the EZ Finder II's red dot should
also appear in the center of the field of view of the telescope's
eyepiece. Alignment of the EZ Finder II is easiest during day-
light, before observing at night. Aim the telescope at a distant
object at least 1/4 mile away, such as a telephone pole or
chimney and center it in the telescope's eyepiece. Now, turn
the EZ Finder II on and look through it. The object will appear
in the field of view near the red dot.
Note: The image in the eyepiece of the telescope will be
upside-down (rotated 180°). This is normal for Newtonian
reflector telescopes.
Without moving the telescope, use the EZ Finder II's azimuth
(left/right) and altitude (up/down) adjustment knobs to position
the red dot on the object in the eyepiece.
When the red dot is centered on the distant object, check to
make sure that the object is still centered in the telescope's
field of view. If not, recenter it and adjust the EZ Finder II's
alignment again. When the object is centered in the eyepiece
and on the red dot, the EZ Finder II is properly aligned with
the telescope.
Once aligned, EZ Finder II will usually hold its alignment even
after being removed from its bracket. If the EZ Finder II's
bracket is removed entirely from the optical tube then realign-
ment will be needed.
5. Setting up and Using the
Equatorial Mount
When you look at the night sky, you no doubt have noticed
that the stars appear to move slowly from east to west over
time. That apparent motion is caused by the Earth's rotation
(from west to east). An equatorial mount (Figure 2) is
designed to compensate for that motion, allowing you to easi-
ly "track" the movement of astronomical objects, thereby keep-
ing them from drifting out of the 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
6
Big Dipper
(in Ursa
Major)
N.C.P.
Figure 5.
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).
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 5). 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).
To polar-align the SpaceProbe 3 EQ:
1. Level the equatorial mount by adjusting the length of the
three tripod legs.
2. Loosen the latitude lock t-bolt. Turn the latitude adjustment
t-bolt 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 lat-
itude setting should not have to be adjusted again unless
you move to a different viewing location some distance
away.
3. Loosen the Dec. lock knob and rotate the telescope optical
tube until it is parallel with the R.A. axis, as it is in Figure 1.
The pointer on the Dec. setting circle should read 90°.
Retighten the Dec. lock lever.
4. Loosen the azimuth lock knob at the base of the equatori-
al mount 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 com-
Little Dipper
(in Ursa Minor)
Polaris
Cassiopeia