Periodic Error Correction

[jambouk]

I've got an AZEQ6. For a laugh tonight, whilst waiting for the clouds to clear, i did two runs of PEC training using the handset, and my ASI ZWO trained on a star. The first run i did at 0.125x (no idea what this means) and it wanted me to make corrections with the left and right directions keys for 8 minutes. I did this but messed up at the start because i was trying to centre the star on the reticule on the laptop screen. The second time i selected 0.25x (to see what the difference was), and it did the same again, but took 16 minutes.

I then told it to track at sidereal rate with PEC; this made the red light on the mount flash three times which worried me and i was checking voltage and the like, but then identified this as normal in the manual.

Anyway, to get to my question.... How does the handset/mount know which of my corrections on the key pad are down to periodic error, and which are down to my poor polar alignment, and which are the random scattering of errors from me pressing the arrow keys at the wrong time, or too much, or not pressing them at all! It seems very hit and miss to me.

I didn't have opportunity to test the new tracking properly as the cloud got worse not better. But there did seem less drift in the RA axis, but still some in the dec axis (the same as before, as one might expect).

Thanks.

Jd

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[Chris Rowland]

Anyway, to get to my question.... How does the handset/mount know which of my corrections on the key pad are down to periodic error, and which are down to my poor polar alignment, and which are the random scattering of errors from me pressing the arrow keys at the wrong time, or too much, or not pressing them at all! It seems very hit and miss to me.

It doesn't. It assumes that your corrections are prefect.  The one thing is that for the 16 minute run it may be averaging your corrections over two of the 8 minute worm cycles.

Most people train PEC by using an auto guider program to keep the star centred. This will probably do a better job than you can.

They may also use a PEC training program such as PEMPro or, for Celestron mounts, PECTool.  These will do multiple training sessions, average, smooth and load the results to the mount.  Also keep a copy locally so you don't loose it.

I don't know exactly how your mount does this, you will need to go through the manual carefully and maybe ask on mount specific forums.

Chris