Guiding Assistance

[Kenn Hopkins]

While using Guiding Assistance I noticed the RA took a dive down to -12" then over time it went back up to a +8". The time it took for the Guiding Assistance to run was 5 minutes. Since the "-" indication means an Eastward movement, in my setup, in order for me to obtain a better balance should I move my counterweight a little to the West?

I'm just brainstorming and curious what the group thinks.

https://openphdguiding.org/logs/dl/PHD2_logs_fBCG.zip

Kenn

[Bruce Waddington]

I think you're misinterpreting what you see.  The best way to look at this is to use the PHDLogViewer tool with two views.  The first shows the native tracking error which usually shows the characteristic sine-wave of periodic error:

If you're just looking at this in real-time, you can't know the phase of the curve at the point you started the GA run.  So the "zero point" for the GA graph can fall anywhere along the sine wave curve, there's no way for you to know. None of this shows anything useful about balance and the curve here is pretty typical for your type of mount.  The second useful view is the frequency/period analysis which looks like this:

You can see your tracking is dominated by a 10 arc-sec peak-peak error with a period of 162 seconds.  You can attack this by using a periodic error correction curve generator app like PemPro or you can use the PHD2 predictive periodic error algorithm for RA.  For the latter, set a period length of 160 seconds and un-check the box for 'auto-adjust'.

Good luck,

Bruce

[Kenn Hopkins]

Ah there is always something interesting to learn in this 'Hobby". I appreciate your explanation and willingness to share this important information.

I will try and follow your advice and more study.

Kenn

[Kenn Hopkins]

May I ask a question? In PEMPro and the PEC generation application is telling me the Worm Cycle is 319.13 and 159.56. PHD2 is showing a period around 162.8; there are a few other high peaks but that is the closest to the Worm Cycle of 159.56 PEMPro is telling me. 

So setting the Predictive Periodic Error Algorithm to ≈160 then PHD2 will be able to handle the peak? I also have a PEMPro generated PEC Curve and the Gemini II has PEC turned on - should I have both of them running or should I turn off the Gemini II PEC activation or run a different algorithm in PHD2?

Appreciate your taking the time to respond.

Kenn

[Brian Valente]

Kenn

You can (and should) have both PEC and PHD's PPEC algorithm enabled. They complement each other

If you know the mechanical period of the mount, i would use that in the PPEC settings. i.e., 159.56 seconds, disable auto adjust period

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Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Kenn Hopkins]

Thank You for the advice.

Kenn