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Even though the CPC can precisely track a celestial object while in the Alt-Az position, it is still necessary to align the polar axis of the
telescope (the fork arm) to the Earth's axis of rotation in order to do long exposure astrophotography. To do an accurate polar alignment,
the CPC requires an optional equatorial wedge between the telescope and the tripod. This allows the telescope's tracking motors to
rotate the telescope around the celestial pole, the same way as the stars. Without the equatorial wedge, you would notice the stars in the
eyepiece would slowly rotate around the center of the field of view. Although this gradual rotation would go unnoticed when viewing
with an eyepiece, it would be very noticeable when imaging.
Polar alignment is the process by which the telescope's axis of rotation (called the polar axis)
is aligned (made parallel) with the Earth's axis of rotation. Once aligned, a telescope with a
clock drive will track the stars as they move across the sky. The result is that objects
observed through the telescope appear stationary (i.e., they will not drift out of the field of
view). If not using the clock drive, all objects in the sky (day or night) will slowly drift out of
the field. This motion is caused by the Earth's rotation.
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The CPC hand control has a polar alignment function called "All-Star" polar alignment that
will help you polar align your telescope for increased tracking precision and
astrophotography. This feature allows you to choose any bright alignment stars to assist in
accurately aligning your telescope and wedge with the North Celestial Pole. Before using the
Polar Align feature, you must first perform an EQ North or South Alignment.
Once your telescope is EQ aligned, slew the telescope to any bright star in its Named Star
database list. This will be the star used for the All-Star Polar Alignment. For best results, it is
always good to choose a polar alignment star that is high in the sky and near the Meridian.
Try to avoid stars that are close to the west/east horizon, directly overhead or too near the
celestial pole.
Press the Align button and use the Up/Down buttons on the hand controller to select Polar
Align from the list.
The Polar Align feature has two options: Align Wedge and Display Align.
Align Wedge- After performing an EQ North or South Alignment and slewing your telescope to any bright star in the
telescope's database, select the "Align Wedge" option. The telescope will then re-slew to the same star.
1.
Center the star in the finderscope and press ENTER.
2.
Then accurately center the star in your eyepiece and press ALIGN. The telescope will then "sync" on this star and
slew to the position that the star should be if it were accurately polar aligned.
For the most accurate alignment it is best to use a reticle eyepiece (see Optional
Accessories) or a high power eyepiece to precisely center the star in the field of view.
3.
Use the wedges latitude and azimuth adjustments to place the star in the center of
the eyepiece. Do not use the direction buttons on the hand control to position
the star. Once the star is centered in the eyepiece, press ENTER; the polar axis
should now be pointed towards the North Celestial Pole.
Updating your Star Alignment
After polar alignment it's a good idea to check the pointing accuracy of the telescope to see how much
it may have been affected by moving the mount. Since the polar alignment process requires you to
"sync" the telescope on a bright star before you begin, it will be necessary to undo the sync before re-
aligning. To undo the sync:
1.
Press the Align button and use the Up/Down buttons on the hand controller to select Undo
Sync from the list, and press Enter. The message Complete will display on the LCD.
To re-align your telescope:
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ALIGN
ALIGNMENT STARS
POLAR ALIGN
ALIGN MOUNT
DISPLAY ALIGN
SYNC
UNDO SYNC
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