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Correct for Atmospheric Refraction in SharpCap PA

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#1 jerahian

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Posted 19 September 2019 - 06:32 PM

For those of you who do use SharpCap for polar alignment, do you enable the "Correct for Atmospheric Refraction" option in the Polar Alignment settings?

 

I ask because my RA guiding has been strained the last couple of times, where PHD2 is pulsing almost totally West.  This has been different than what it was before and I'm trying to figure out what I changed recently that may contribute to that, and I did recently enable this option in SC.  I'm just debugging...

 

Thanks,

Ara



#2 Tim C

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Posted 19 September 2019 - 07:59 PM

Yes, I use it & with no issues.  I believe you'd see lots of correction in one direction either North or South if polar alignment was off (vs. East or West).



#3 Zebenelgenubi

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Posted 20 September 2019 - 07:51 AM

I use the atmospheric correction as well from down here in Texas.  Polaris ought to be pretty high above the horizon from Maine and the correction will be small.



#4 jerahian

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Posted 20 September 2019 - 09:14 AM

Thanks guys, there must be something else going on.  I incorrectly mentioned above that the PHD2 pulsing was mostly West, when in fact it has been mostly East.  I don't think the direction matters though.  I agree it has something to do with the PA, but other than that setting, my PA has always been the same process every time since April.

 

I imagine an imbalance in RA would cause this to happen as well, correct?  I normally do not balance East heavy in RA or camera-end heavy in Dec.  I try to have everything just well-balanced, so I wonder if I have gotten loose in my balancing routine.

 

One more thing I found out which is odd.  The last couple of times where I saw this, I did a recalibration and found that the RA & Dec axes PHD2 calculation were not 90 degs!  I'll have to get the logs to see how far it was off.  It had always been almost perfectly 90 degs every time before then, with no perceptible backlash.  Again, I imagine these two are related.  Would you guys agree these are related?

 

Ara




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