Periodic Errors are found in almost all worm gears due to slight eccentricities and misalignments. The
PEC (Periodic Error Correction) Training function provides a manual correcting method to reduce the
amplitude of the worm errors. By recording a full cycle of guiding actions versus motor shaft angle,
EQ6 SkyScan
TM
can work to compensate for the drifting in the RA sidereal tracking caused by the
periodic errors. Below describes a step-by-step procedure on how to perform the PEC:
PEC Training
Perform the accurate Polar Alignment method (see Enhancing the Precision).
Slew or manually point the telescope to a star with smaller DEC coordinate. This
object will be used as the guide star.
Activate Sidereal Tracking from the Setup Menu (see Setup Functions on page.14).
Once the tracking has started, press ESC to go back to the Setup Menu.
Rotate the reticle eyepiece until one set of the lines becomes parallel to (or matches)
the R.A. movement of the telescope (see step 2 to 4 of the Cone Error Calibration for
more information on how this is done.)
Move the guide star back at the center of the eyepiece view using the direction keys.
On the hand control, select PEC Training in the Utility Functions and press ENTER.
1.
2.
3.
4.
5.
6.
The hand control will ask you to select the R.A. guide speed for the PEC recording.
See the following chart for details on the two settings.
7.
8.
9.
Required accessory: Illuminated
reticle eyepiece with double crossline
pattern capable of producing at least
300X magnification in combination
with your telescope. The true field of
view should not exceed 10 arc min.
See Choosing the appropriate
eyepiece for more information on
calculating the field of view.
Utility Functions can be easily accessed by pressing the UTILITY quick reference
hotkey on the keypad.
VIII
R.A.
The Guide star drifts away from
the center
Fig.w
Adjust the telescope to move the
guide star back to the center
R.A.
Fig.w-1
PEC Training function is
recommended for advanced
users interested in long-
exposure astrophotograhy only.
Careful guiding is required.
Regular sidereal tracking is
adequate for all casual visual
use of the EQ6 SkyScan
TM
and
PEC Training is not required.
Northern Hemisphere
Southern Hemisphere
RIGHT
key
1.25X Sidereal
1.5X Sidereal
LEFT
key
0.75X Sidereal
0.5X Sidereal
RIGHT
key
0.75X Sidereal
0.5X Sidereal
LEFT
key
1.25X Sidereal
1.5X Sidereal
0.25X Speed
0.5X Speed
The EQ6 SkyScan
TM
hand control will display a timer once the guide speed is selected,
indicating that the recording has begun.
Using the LEFT or RIGHT direction key only, move the telescope so the guide star
remains at the center of the eyepiece view (Fig.w, w-1). Repeat whenever necessary.
Summary of Contents for EQ6
Page 24: ...VI...
