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Don Waters

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Oct 11, 2025, 8:06:31 AMOct 11

to Open PHD Guiding

https://openphdguiding.org/logs/dl/PHD2_logs_6WGq.zip

Would you look at these please, and give me some advice?

I initially had calibration issues and adjusted the balance of the OTA and that improved the calibration for the result here.

I changed the exposure from 1 to 2 sec to minimize seeing issues.

While running the GA, I noticed that the PA error gradually decreased to 0 and then began increasing. Can you shed some light on how this calculation works?

I seem to have some pretty big swings in RA. I would appreciate ways to track this down. (I'm wondering if I need to look at things like cabling, vibration, DF, etc.)

Thank you.

Don

Bruce Waddington

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Oct 14, 2025, 5:30:58 PMOct 14

to Open PHD Guiding

The PHD2 estimates of polar alignment error come from measures of drift in declination. We have no way to know whether there are other contributors to declination drift beyond polar alignment error, things like mechanical flexure or orthogonality errors in the calibration. If you are getting single-digit estimates of polar alignment error over a sampling interval of at least 2 minutes, you shouldn't be worrying about it.