Thread: Polar Alignment
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Old 07-03-2020, 09:12 AM
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Outcast (Carlton)
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Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,140
Peter,

After your two star alignment, run the PA routine in the Synscan handset as per the manual; To be honest, if you are doing visual then doing a PA is not entirely necessary however, if you are doing AP, a good PA is essential & it's worth running this routine a couple of times at least to refine the PA down.

11.3 Polar Alignment without Polar Scope

1. Complete a 2-star alignment or a 3-star alignment. At the end of the alignment, the SynScan hand control will display the polar alignment error (refer to Section 3.3). Users can use the data to determine whether it is 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”). Users can then use the data to determine whether or not to adjust the altitude of the R.A. axis in the next step. Press the ENTER key to proceed.

6. The mount will slew to a new position. When it stops, the screen will display “Adjust Altitude:”. By using ONLY the altitude control of the mount (do not touch the azimuth control), 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 current 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. Users can then use the data to determine whether or not to adjust the azimuth of the mount in the next step. 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 control of the mount (do not touch the altitude control), 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.

10. Go back to the “Alignment” menu on the SynScan hand control 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 9 until the error is small enough and acceptable. Generally, users can get up to 1 arc-minute polar alignment accuracy after repeating this polar alignment process 2 or 3 times.

Note:
• Users can press the ESC key at any time during the polar alignment process to exit.The initial polar alignment should not be too far off to avoid the polar alignment error in azimuth axis from exceeding the adjustment range of the mount.
• It is necessary to use a reticle eyepiece in the 2-Star alignment, 3-star alignment and polar alignment process.
• Generally, the cone error in a telescope-mount setup might reduce the accuracy of this polar alignment process. Therefore, it is recommended to reduce or eliminate the cone error before the polar alignment process (Refer to APPENDIX 1 : ELIMINATING CONE ERROR ON EQUATORIAL MOUNTS).
• It is recommended that the user verify the accuracy of the 2-star alignment or 3-star alignment before starting the polar alignment process by locating several objects in different areas of the sky. If the pointing accuracy is low, try to use another set of alignment stars for the 2-star or 3-star alignment process.

Cheers
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