Sky-Watcher Synscan Hand Control - Manual (Page 8)

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PART III : ALIGNMENT
1. The LCD screen displays “ Choose 1 st Star ” in the first line. Use the scrolling keys to browse
through a list of star names and Press ENTER key to pick the one on the screen as the 1st
alignment star.
2. Now the screen will display “ Point scope to ZZZ zz.z’ sTT tt.t’ ”, which means point the tele-
scope to the direction whose azimuth is ZZZ degree, zz.z minutes and whose altitude is
sTT degree, tt.t minutes. This is also the direction of the selected 1 st alignment star. Users
can use the direction keys on the SynScan hand control to move the mount to point the
telescope to the star and center the star in the FOV of the finder scope or the red dot finder,
and then press ENTER key to proceed to the next step.

If the telescope has clutches on its axes, user can loosen the clutches to move the mount
manually to point the telescope to the target.
3. Now the screen will display “ Ctr. to eyepiece.. ” and the name of the selected 1 st alignment
star. The star should have been in the FOV of the telescope. User can use the direction
keys to center it in the eyepiece and then press the ENTER key to proceed to the next step.
3.5 Alt-Azimuth Mounts using 2-Star Alignment Method
Aligning the 1 st Star:
Aligning the 2 nd Star:
1. The LCD screen displays “ Choose 2nd Star ”. Use the scrolling keys to browse through a list
of star names and Press ENTER key to pick the one on the screen as the 2 nd alignment star.
The mount will then automatically slew and point the telescope towards the 2 nd alignment
star in the sky.
2. After the mount stops, the hand control will display the name of the selected 2nd alignment
star and “
Ctr. to eyepiece..”. The telescope should point rather closely to the 2 nd alignment
star (generally, in the FOV of the finder scope.)
3. Now users can use the direction keys to move the telescope to align with the 2 nd alignment
star. To align, center the 2 nd alignment star in the FOV of the finder scope, and then center
it in the FOV of the telescope’s eyepiece. Press ENTER key to confirm centering of the star
and proceed to the next step. Generally, users can use Rate 5 or 6 to center the star in
finder scope and use Rate 2 or 3 to center the star in the telescope’s eyepiece.
4. The SynScan hand control will now display “ Alignment Successful ”. Press ENTER to com-
plete the alignment process.
Cancellation During Aligning Process:
1. While the mount is slewing during alignment, users may press the ESC key to stop the
mount. The hand control screen will display “ MOUNT STOPPED!! Press any key… ”
2. Press any key and the SynScan hand control will ask the user to select another alignment
star.
3. Press the ESC key again; the LCD screen will display “ Exit Alignment? 1) YES 2) NO ”. Press
key 1 to exit the alignment process; press key 2 to go back to choose an alignment star.
PART III : ALIGNMENT
Eyepiece
It is very important to put the alignment stars at the center (or the same spot) of the FOV of the
telescope’s eyepiece during the alignment process. Thus,
• It is recommended that a reticle eyepiece is used for alignment.
• If a reticle eyepiece is not available, try to use an eyepiece with shorter focal length to yield
a smaller FOV. Users can defocus the telescope to obtain a large star disk in the FOV.
Centering the star disk in the FOV is easier than centering a sharp star.
• During the alignment process, avoid changing or rotating the eyepiece and the diagonal
mirror.
Mechanical Backlash
All mounts have more or less mechanical backlash on both axes. To avoid introducing align-
ment error from backlash, users should keep the following rules in mind:
• When centering an alignment star in the eyepiece, the operation should always end by
using the UP and RIGHT direction keys to move the axes.
• If there is overshoot when centering alignment star in eyepiece with UP or RIGHT keys, use
the LEFT or DOWN keys to pull the star back to the edge of the FOV and then use the RIGHT
or UP keys to center the star again.
Alignment Stars Selection
The choice of alignment stars might also impact the alignment accuracy. Please
refer to Sec-
tion 3.7 on the rules of choosing alignment stars for various mounts and alignment methods.
3.6 Tips for Improving Alignment Accuracy
Rules for choosing an alignment star:
• Choose an alignment star with smaller declination. It will help to obtain higher resolu-
tion in R.A. movement in the telescope’s eyepiece.
• If there is cone error in the telescope-mount setup or if users are not sure about it, it is
recommended to choose an alignment star that is close to the object(s) to be observed.
Advantage: Quickest alignment.
Preconditions:
• An accurate polar alignment for the mount.
• Small cone error in the telescope-mount setup.
If the cone error is large, there will be noticeable offset in the R.A. when the SynScan
hand control locates an object that is:
1. Equatorial Mount with 1-Star Alignment:
3.7 Comparison of Alignment Methods
» On the other side of the meridian from the alignment star
» Deviated significantly with the alignment star in declination.