Image Acquisition and the King Method

C2As image processing tool allows you to directly acquire images from a sensor controlled by MaximDL software. At this time, only MaximDL is supported by C2A, and you must have installed this software on the machine which runs C2A. MaximDL Version 4.62 or later is recommended.

Acquisition is done simply by specifying the length of exposure and the pixel binning and then by pressing the button to the right of the box.

The image acquisition module incorporates a tool which allows you to easily polar align a telescope using the King method. This is done as follows:

1. Point the telescope as close as possible to the North celestial pole (near the star Polaris).

 

2. Enable sidereal tracking of the mount.

 

3. Launch MaximDL and set camera options (filter, temperature, etc).

4. Launch C2A and open the image processing window (F11 key)

 

5. Specify an exposure time for the images that will be made during the King polar alignment process (typically between 1 and 5 seconds)

6. Specify a time separating the two King method exposures in the box at the bottom left of the Acquisition area. You would typically use 10 minutes, or 600 seconds, so that stars have time to drift significantly. Note that you can start the iteration process with lower time values.

7. Launch the King method by clicking the button at the bottom of the Acquisition area. A first image is then taken and displayed.

8. A small log window with command buttons is displayed on the screen.

9. Adjust the thresholds of the image, then select a bright (but not saturated) star and draw a rectangle around it. Once the star has been selected (you can verify that the selection is ok in the PSF area of the image processing window), click the Continue button in the small dialogue window. A red ring is displayed around the selected star.

10. When the time interval between the two King method exposures expires, a second image is automatically taken by C2A.

 

11. Select the same star as in the first image. A yellow ring is then displayed on the image. Click Continue. A blue ring is then displayed on the image which indicates the position to which the star used must be brought to correct the polar alignment.

12. Adjust the zoom level so that the reference star and the position to which it must be brought can be seen clearly. Click Continue.

13. C2A then enters a loop of image acquisition. Then simply adjust azimuth and height of the mount to bring the reference star inside the blue circles in the image.

 

14. Once the reference star is at the correct position in the blue circles, stop the King method by clicking the Stop button.

Steps 7 to 14 would usually be repeated twice to get a good quality polar alignement.

Table of Contents