Understanding PHD2 LogViewer Information

[André Vilhena]

Hello,

I would like some help for me to better understand PHD2 LogViewer information, namely the frequency analysis. Taking a log of mine as example (see attached), I understand the following:

1) The RAW information shows the behaviour of the mount were it not corrected. In this case, it has three main peaks at 487, 120 and 68 seconds.

2) The mount has a PPEC correction (not the algorithm) built-in. The 487 sec peak (for example) in the RAW is 3 arcmin tall is the performance taking the PPEC in account. It would be taller if PPEC wasn't applied.

3) The non-RAW information represents the performance of the guiding including the correction performed by PHD2. In this case, PHD2 managed to lower the 487 peak from 3'' to 0,25'' (give or take) - this is the performance of PHD2.

4) Wind/cloud effects: this guiding was taken with some wind and high clouds. This should not matter as the effects will be seen at high frequencies.

Am I correct on the above or is anything missing/incomplete?

Many thanks in advance!

André

[Brian Valente]

>>>1) The RAW information shows the behaviour of the mount were it not corrected. In this case, it has three main peaks at 487, 120 and 68 seconds.

I assume "RAW" means the RA corrections backed out, and yes this is the case. Just be careful this isn't actually 'raw performance', it's an estimate of mount performance unguided. the estimate is by backing out the RA corrections. If you wanted to measure true unguided performance you would do an unguided run

 

>>>2) The mount has a PPEC correction (not the algorithm) built-in. The 487 sec peak (for example) in the RAW is 3 arcmin tall is the performance taking the PPEC in account. It would be taller if PPEC wasn't applied.

Presumably, yes. But again, no way to know for sure without seeing the version with mount-based PEC disabled. 

>>>3) The non-RAW information represents the performance of the guiding including the correction performed by PHD2. In this case, PHD2 managed to lower the 487 peak from 3'' to 0,25'' (give or take) - this is the performance of PHD2.

correct, it shows the results with corrections applied

>>>4) Wind/cloud effects: this guiding was taken with some wind and high clouds. This should not matter as the effects will be seen at high frequencies.

It could, but remember this isn't the whole picture: this is the picture of *periodic errors*, i.e., repeatable errors on a regular interval. Things that aren't regular intervals (wind, clouds, etc.) should not impact this

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Brian Valente

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