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d. Thread the two provided
l/4-20
threaded attachment
knobs through the mounting slots into the ETX base.
Tighten to a firm feel only. Do
not
overtighten or damage
to the threads may occur.
The ETX Astro Telescope can be used for land or celestial
observing.
To track celestial objects, polar alignment is
required, along with the motor drive system of the ETX. (See
the Motor Drive section of the ETX instruction manual.)
POLAR ALIGNMENT
Polar alignment is the process of lining up the telescope’s polar
axis with the North Celestial Pole (or South Celestial Pole if
observing from the southern hemisphere).
With a polar aligned ETX, tracking celestial objects is possible
simply by turning on the drive motor in the base of the telescope.
The motor counteracts Earth’s rotation, keeping objects in the
field of view. Also, with a polar aligned telescope, the
ETX’s
Dee
and R.A. setting circles may be used to locate faint objects
directly from their catalogued coordinates.
.
Fig. 3. (left) The ETX Astro Telescope on
Field
Tripod.
ownted
for
land
wewIng.
(right)
The
polar-allgned
ETX, ready for
astronomlcal
wewng.
1.
Polar Alignment Procedures
Make sure the ETX is firmly attached to the tripod, as described
above In this
tnstruction
sheet, with
latitude
lock knob (10) and
the
latitude
lock lever (11) Fig
1.
firmly locked
Step (a) below IS equrvalent to pointing the telescope’s polar
axls due north (or due south for observers in the southern
hemisphere). Step (b) IS equrvalent to
makrng
the telescope’s
latitude angle equal to the latitude angle of your
obset-vmg
location.
a.
On top of one of the tripod legs, locate the letter
“N”
(8)
Fig.
1.
This represents the north leg of the tnpod.
Prck
up
the entire telescope-and-tripod and onent the tripod
u
tf@
lea marked
“N”
points due north. For observers
In
the
southern hemisphere (e.g.,
Australra),
the lea marked
“N”
should
pornt
due south.
b.
Determine the latitude of your observing
locatron
by
checking a road map, atlas, or refer to pages 12-13 of the
ETX manual. To set the latitude of the tripod to your
obseN!ng location, loosen the latitude lock knob
(lo),
Fig. 1. Turn the fine latitude adjustment knob
(4)
Fig. 1,
clockwise or counterclockwise until the latitude pointer
Indicates the correct latitude on the latitude scale
(3)
Fig. 1.
It may be necessary to loosen the lock nut on the fine
latitude adjustment knob
(4)
Fig. 1, to allow enough
movement of the mount to achieve the latitude of your
location. Once the
desrred
latitude has been set, tighten
the lock nut until it is flush agamst the mount.
Trghten
the
latitude lock knob
(lo),
Fig.
1,
as well.
.
Note: The fine azimuth adjustment knobs
(9),
Fig.
7,
which
move the telescope horizontally without moving the tripod itself,
may be used to aId
m
the alignment procedure.
Note:
By following the procedures listed above, the ETX
telescope is polar aligned for most celestial observing
applications. See Figure 3. Approximate polar alignment is
*
sufficient in the great majority of these applications. Do not
allow a time-consuming effort at precise polar alignment to
interfere wifh your basic enjoyment of the telescope, as such
precise alignment is, in general, not reqtiired.
Using the North Star, Polaris, to find North aids in the polar
alignment procedure. Polaris can be found in relation to the Big
Dipper by projecting a line from the so-called “pointer stars” of
the Big Dipper. For southern hemisphere alignment, locate
south by using the faint star Sigma
Octans
(the South Star)
0
*...__b
*...“’
Cassiopeia
Fig. 4: Locating Polaris.
2.
Using a Polar Aligned Telescope
Once the telescope is polar aligned, the ETX motor drive will
keep a celestial object in the field of view of the telescope.
a.
b.
C.
d.
e.
3.
To center a celestial object within a polar aligned
telescope, unlock the
Dee
and R.A. lock levers of the
telescope (see the Locating Astronomical Objects section
of the ETX instruction manual). Do not move the tripod or
adjust the latitude angle when centering an object in the
telescope, as this will destroy the polar alignment.
Once a celestial object has been centered in the
telescope, lock the
Dee
and R.A. lock levers.
Locate the On/Off switch on the bottom of the ETX drive
base and turn on the motor drive. The motor drive will
keep the celestial object within the telescope’s field of
view.
Note:
Depending on the accuracy of the alignment
procedure, it may be necessary to use the R.A. and
Dee
Slow Motion Controls to make minor adjustments to keep
the celestial object in the field of view.
The motor drive disengages when the R.A. and
Dee
lock
levers are unlocked and re-engages when the lock levers
are locked, making it possible for the motor drive to remain
on during the entire observing session.
At the end of an observing session, remember to turn off
the motor drive.
Terrestrial Use of the Field Tripod
In land viewing applications, the three legs of the Field Tripod
may be
posrtioned
In
an arbitrary orientation. The telescope
mounting, however, should be placed in a horizontal positron:
(Fig.
3)
by turning the fine latitude adjustment knob
(4)
Frg.
1,
to read
90”,
unlocking and
re-lockrng
the latitude lock knob‘(lO),
Fig.
1, to accomplish this adjustment. The
ETX’s
motor drive
should be turned off
In
terrestnal applications.
Use the
telescope’s R.A. and
Dee
slow-motion controls for fine motion in
horizontal and vertical.
If you have any questions regarding the use of the ETX Field
Tripod,
please call Meade Customer Service at
(949)
451-1450.