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ALT/AZ:
Tripod head
locked at 90°
POLAR:
Tripod head
locked at
observer's
latitude
Fig. 3: Examples of Alt/Az (left) and polar mounting (right) of an
ETX-90EC to the #883 Deluxe Field Tripod.
POLAR ALIGNMENT
Polar alignment (Fig. 3) 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 telescope, tracking celestial objects is
possible by simply turning on the drive motor in the base of the
telescope. The motor counteracts the Earth's rotation, keeping
objects in the field of view. Also, with a polar-aligned telescope,
the telescope's R.A. and Dec setting circles may be used to
locate faint objects directly from their catalogued coordinates.
Polar Alignment Procedure
Make sure the telescope is firmly attached to the tripod, as
described above, with the latitude lock knob (11, Fig 1) and the
latitude lock lever (12, Fig. 1) firmly locked.
Step 1 below is equivalent to pointing the telescope's polar axis
due north (or due south for observers in the southern
hemisphere). Step 2 is equivalent to making the telescope's
latitude angle equal to the latitude angle of your observing
location.
1.
On top of one of the tripod legs, locate the letter "N"
(9, Fig. 1). This represents the north leg of the tripod. Pick
up the entire telescope-and-tripod and place the tripod so
that the leg marked "N" points due north. For observers in
the southern hemisphere (e.g., Australia, South America,
Africa, etc.), the leg marked "N" should point due south.
2.
Determine the latitude of your observing location from a
road map, atlas, or refer to the telescope instruction
manual. To set the latitude of the tripod to your observing
location, loosen the latitude lock knob (11, 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 desired latitude has been set, tighten
the lock nut until it is flush against the mount. Tighten the
latitude lock knob (11, Fig. 1) as well.
NOTE: The fine azimuth adjustment knobs (9, Fig. 1), which
move the telescope horizontally without moving the tripod itself,
may be used to aid in the alignment procedure.
Meade Instruments Corporation
World's leading manufacturer of astronomical telescopes for the serious amateur.
6001 OAK CANYON, IRVINE, CALIFORNIA 92620-4205 U.S.A.
(949) 451-1450
Version 0799
FAX: (949) 451-1460
www.meade.com
Little Dipper
Big Dipper
Fig. 4: Locating Polaris.
By following the above procedure, the telescope is polar-
aligned for most celestial observing applications. Approximate
polar alignment is sufficient in the great majority of these
applications.
Important Note: For almost all astronomical observing
requirements, approximate settings of the telescope's latitude
and polar axis are acceptable! Do not allow undue attention to
precise polar alignment of the telescope to interfere with your
basic enjoyment of the instrument.
Using the North Star (Polaris) to find North will aid in polar
alignment. Polaris can be found in relation to the Big Dipper by
projecting a line from the so-called "pointer stars" of the Big
Dipper (Fig. 4). For southern hemisphere alignment, locate
south by using the faint star Sigma Octans (the South Star).
Using a Polar-Aligned Telescope
Once the telescope is polar-aligned, the telescope motor drive
will keep a celestial object in the field of view of the telescope.
1.
To center a celestial object within a polar-aligned
telescope, see the appropriate section in the telescope's
instruction manual (for the ETX-90RA model, see
Locating Astronomical Objects; for ETX-90EC and
ETX–125EC models, see Observing with the Electronic
Controller). Do not move the tripod or adjust the latitude
angle when centering an object in the telescope as this
will destroy the polar alignment.
2.
Activate the telescope's motor drive. The motor drive keeps
celestial objects within the telescope's field of view.
•
ETX-90RA: The On/Off switch is located on the
bottom of the drive base.
•
ETX-90EC or ETX–125EC: See the Modes of
Operation section of the telescope's instruction
manual.
NOTE: Depending on the accuracy of the alignment procedure,
it may be necessary to use the R.A. and Dec slow-motion
controls (ETX-90RA) or the Electronic Controller arrow keys
(ETX-90EC or ETX-125EC), to make minor adjustments to
keep celestial objects in the field of view.
3.
The motor drive disengages when the R.A. and Dec lock
levers are unlocked and re-engages when the lock levers
are locked, making it possible for the motor drive to
remain on during an entire observing session.
4.
At the end of an observing session, remember to turn off
the motor drive.
If you have a question concerning use of the #883 Deluxe Field
Tripod, call the Meade Instruments Customer Service
Department at (949) 451-1450, or fax at (949) 451-1460.
Customer Service hours are 8:30 AM to 4:30 PM, Pacific Time,
Monday through Friday.
Polaris
Cassiopeia
14-4010-01
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