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Polar alignment without pole visibility

This tool is designed to be as quick and easy to use as possible to help to refine the mount polar alignment. It can be run on any part of the sky and not require pole visibility.

To start the procedure select the menu Tools → Polar alignment, without pole visibility

Before starting this tool the mount must be pole aligned as good as possible. The camera must be connected and the mount initialized to allow to slew and report it's coordinates.
It is very important the observatory location is set in the preferences and the computer time is set with a reasonable precision.
The camera uses the Slew setting exposure, binning and filter. Be sure this setting give a fast enough image refresh.
If slewing is configured to use a finder camera, this finder is also used for the polar alignment.

Select where you want to run the measurement. It is recommended to use one of the predefined option, but if all point to obstructed part of the sky you can define the azimuth and altitude of the two measurement points.

When ready click the Start button.

The telescope will move to the two points, take a preview image and plate solve.

After it complete, you have the choice to directly go to the adjustment screen with the Next button or to move the telescope a bit to show a bright star or an area that is more easy than the current field.

If you click Move the program start an image loop and you can move the telescope with the handpad until it show a bright star. When this is done click Continue.

Then it show the correction to do on the mount in both the horizontal and vertical axis.

The direction are to be interpreted this way:

  • move East : is moving the mount horizontal knob so the top of the polar axis move to the east.
  • move West : is moving the mount horizontal knob so the top of the polar axis move to the west.
  • move Down : is moving the mount vertical knob so the top of the polar axis move down.
  • move Up : is moving the mount vertical knob so the top of the polar axis tube move up.

Adjust the luminosity slider so the sky background is dark enough to clearly see the guide lines.
Move the green circle at an extremity of the line to a star you can easily recognize later, for example a star that is part of a small figure, or the brightest star on the image.
You can zoom on the image with the mouse wheel to help to center the star. Press the Ctrl key if you need to move the image instead of the overlay.
It is also possible to double click to select the star nearest to the mouse cursor.
When the overlay is in place, click the button Lock overlay, this way you can zoom and move the image without the risk to move the overlay.

Now the goal is to move the star to the pink circle at the other extremity of the line by using only the mount polar axis adjustment knob. To help with this movement the azimuth movement is represented by the blue line and the altitude movement by the red line.

During all this procedure you can change the exposure time of the preview but do not change the geometry of the image, no change of binning or ROI!

After the star reach the pink circle you can close this screen, the alignment procedure is complete.

When using a plate solving application that is fast enough, for example ASTAP, you can check the box Plate solve to update the correction

This continuously update the correction value in arc minutes for both direction.

en/documentation/polar_alignment_2_points.txt · Last modified: 2024/03/17 17:40 by pch