19
• After turning on the PEC + Sidereal replay, wait for at least one
worm cycle before taking a picture.
• To re-use the PEC data on a mount that supports SPEC, users
should “park” the telescope before shutting off power (refer to
Section 6.3
). This stipulation does not apply to mounts that
support PPEC.
6.6 Calibrating Auto-Home Offset
The Orion HDX110 EQ-G mount has an Auto-Home function
that can automatically set the mount to a standard home posi-
tion after turning on the power. The offset of the home position
can be calibrated and compensated with the following procedure:
1. Accurately polar-align the HDX mount.
2. Turn off the power, then turn it on again, and then initialize
the hand controller.
3. When the SynScan hand controller displays “Auto-
Home?,” press the “1” key to execute the auto-home
process.
4. Finish the subsequent initialization steps.
5. At the end of the initialization, choose 1-star alignment to
align the mount.
6. At the end of the 1-star alignment, the hand controller
will ask “Update H.P.O? 1) No 2) Yes” (“H.P.O.” stands for
Home Position Offset).
• Press “1” to keep the original Home Position Offset.
• Press “2” to use the results obtained from the 1-star
alignment to calibrate the home position offset.
6.8 Polar Alignment without Polar Scope
Polar alignment of your mount by means of the polar-axis scope
is covered in the instruction manual for the mount.
However, there is another, more accurate way to polar align.
This software-based polar alignment routine can be performed
without use of the polar-axis scope. You will need to use a reticle
eyepiece for this procedure to ensure precise centering of the
stars in the eyepiece field of view.
1. Complete a 2-star alignment or 3-star alignment. At the
end of the alignment, the SynScan hand controller will
display the polar alignment error in altitude (Maz) and
azimuth (Mel) (refer to
Section 5.17
). Based on the error
given, you can decide whether it will be necessary to
adjust the polar alignment.
2. Press the “MENU” shortcut key, and then access to
sub-menu “Alignment\Polar Alignment”. Press the ENTER
key to proceed to the next step.
3. The screen will display “Select a Star”.
• Use the scroll keys to browse through a list of star
names and press the ENTER key to pick one as the
reference star for polar alignment.
• The mount will start slewing to point the telescope to
the reference star.
4. Use the direction keys to center the reference star in the
eyepiece of the telescope after the mount stops slewing.
Remember to end the centering operation with Up and
Right direction keys. Press the ENTER key to proceed to
the next step.
5. The screen will now display the polar alignment error in
altitude (Mel=dd°mm'ss"). You can then use the data to
determine whether or not to adjust the altitude of the R.A.
axis. Press the ENTER key again to proceed to the next
step.
6. The mount will slew to a new position. When it stops,
the screen will display “Adjust Altitude:” By using ONLY
the altitude adjustment mechanism of the mount (DO
NOT touch the azimuth adjustment mechanism and
DO NOT use the direction keys on the hand controller),
bring the reference star back to the closest point to
the center of the FOV of the telescope’s eyepiece.
Remember the reference star’s position in the eyepiece
for later adjustment. Press the ENTER key to confirm the
centering operation.
7. The screen will now display the polar alignment error in
azimuth (Maz=dd°mm'ss"). You can then use the data
to determine whether or not to adjust the azimuth of the
mount. Press the ENTER key again to proceed to the next
step.
8. The mount will slew to a new position. When it stops,
the screen will display “Adjust Azimuth:” By using ONLY
the azimuth adjustment mechanism of the mount (DO
NOT touch the altitude adjustment mechanism, DO NOT
use the direction keys on the hand controller), bring the
reference star back to the closest point to the previous
position (at the end of
Step 6
). Press the ENTER key to
confirm the centering operation.
9. The screen will display the polar alignment error again,
press the ENTER button to end the polar alignment
process. It should be an improvement over what was
given in
Step 1
.
10. Go back to the “Alignment” menu on the SynScan hand
controller and execute another 2-Star or 3-Star alignment,
and then check the polar alignment error data reported
at the end of the 2-star alignment or 3-star alignment.
Repeat
Step 2
to
Step 8
until the error is small enough
to be acceptable. Generally, you can expect to get up to 1
arc-minute polar alignment accuracy after repeating this
polar alignment process 2 or 3 times.
6.9 Setting Cone Error and Non-Perpendicular
Error
• Cone Error (CE) occurs when a telescope’s optical axis is not
perpendicular to the equatorial mount’s declination axis (or
the alt-azimuth mount’s altitude axis).
• Non-Perpendicular Error (NPE) occurs when the mount’s two
axes are not orthogonal.
Without proper compensation, both of the above errors could
lead to inaccurate pointing when the telescope system tries to
locate a celestial object automatically. The value of these errors
can be compensated for with settings on the hand controller.
