INDI Library v1.9.8 Released (29 Sep 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

Polar Alignment Help

  • Posts: 9
  • Thank you received: 1
I am trying to use the polar alignment module with my Stellarvue SVX-102T (714mm FL @ 101.5mm) main scope and QHY183C Camera (2.4um pixels at 5544*3694).  When I polar align, I use the following process:
  1. Setup the tripod and level it.
  2. install the mount on the tripod.
  3. Place my cellphone in the saddle of the mount and use the daytime alignment mode in PS Align Pro.  If you're not familiar with this, the app will display a bullseye and a set of crosshairs.  I move the tripod and adjust the Altitude/Azimuth knobs to center the crosshairs on the bullseye.
  4. I complete the setup by installing my scope, guidescope, camera etc
  5. I run Capture and Solve with the option of "Sync" as this appears to prevent the solver from crashing.  The results are:
    1. Effective FL of 736mm
    2. FOV 62.1' x 41.3'
When run the polar alignment routine I get a polar error of a little more than 1 degree.  The issue I have is that the endpoint of the vector is always off the image no matter where I selected the star.  In order to try to get closer, I repeated the polar alignment process several times trying to get closer.  At one point I had a total polar error of 51', but that was as close as I could get. The red circle would disappear after some time, so I suspect that I kept overshooting the end point.   Help.

9 months 3 weeks ago #80392

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Replied by Hy Murveit on topic Polar Alignment Help

When I get a big alignment error (i.e. greater than the image size) I run Polar Alignment but just move the target star as far as possible towards the edge and stop there.
Once I've hit the edge, I repeat polar alignment from the beginning, and the calculated error is smaller and hopefully the target is on the image the 2nd (or 3rd) time doing this.

If you are way off, just use a finder scope or just eyeball it and point your mount towards Polaris (assuming northern hemisphere) before you start.

AP1100 & Orion Atlas Pro, WO/ZS105 w/Moonlight V2 focus, GSO RC10 w/RSF focus
ZWO ASI1600, Astronomik Filters, ST80, QHY 5L-IIm.
KStars/Ekos/Indi on NUC10 & RPi4 w/SSD -- Ubuntu
Projects: Greedy Scheduler, Terrain, Polar Align, Analyze, Linear Focuser, SEP MultiStar & GPG Guide, FITS autostretch.
The following user(s) said Thank You: James Zhen Yu
9 months 3 weeks ago #80394

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Replied by Ron DeBry on topic Polar Alignment Help

It also helps to learn which direction to move for a + vs - deviation in azimuth (pretty obvious for elevation ). If I do a quick setup of the mount and I get a negative degree off in az, I knew to rotate the whole mount clockwise a bit. Then I just run polar align again from scratch. By then the triangle fits on the screen and I use the adjustment knobs.
9 months 3 weeks ago #80396

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