Re: AP-1100 Guiding Questions


Hello Horia

You would need to provide your  guidelogs to really know what is going on. Screen captures are interesting, but don't tell the whole story

If this is a new (to you) mount, i highly recommend you run a baseline guiding by following these steps (this is what we use in the PHD user forums) and then provide your guidelogs.

As someone else pointed out, your corrections are in one direction, which usually indicates polar misalignment, but i also see some axis bleed which could mean you have orthogonality issues in your calibration. Looking at a baseline guidelog will clarify what is going on


On Wed, Dec 8, 2021 at 2:24 AM Horia <ATM@...> wrote:

My AP-1100 (August 2021, no encoders) shows, most of the time, slightly worse guiding in Dec than in RA. A typical example (one 300sec frame) looks like this:



The blue curve is the RA and the red one is the Dec. The gray area on the left is the settling time after a dither. For a better view:


The guiding parameters:

  • Guiding scale: 1.05 arc-sec / pix
  • Exposure: 2000msec
  • Time lapse: 500msec
  • Guide Speed: 15 arc-sec / sec (both RA and Dec)
  • Min move RA: 0.3pix, Aggression: 0.75
  • Min move Dec: 0.4pix, Aggression: 0.8


And the resulting rms values are:

I am imaging at 0,9 arcsec/pix and the difference between RA and Dec values can be clearly seen as a small elongation in N/S direction.


I have the feeling that the Dec axis have somehow more play compared to the RA. I have adjusted the backstop more than once without seeing an improvement.


Is this normal behavior for the Ap-1100?

The system is balanced as close to perfect as I could do it. Should I unbalance the Dec axis to be backside heavy?

Is there something else I should do?


Kind regards,





Brian Valente

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