Tracking OK but PHD2 says PA Error is HUGE....

[Ramius]

Hi,
I am waiting for a clear night to look into this further but am hopeful someone can steer me in the right direction...
I am very new to this but am using NINA 3 Point for PA and getting OK tracking with my AZ-EQ5 mount and small refractor (RMS 0.76" Total)
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I figured this can be improved (as minimum exposure is probably too short) so ran PHD2 Guide Assistant to optimise and got attached result. I don't really know how to interpret this other than to apply the recommendations which i will do on next outing - but i do know the PA Error should not be 260 arc-min :eyepop:.
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Presumably it can't really be that bad (4 degrees!) - and if it were surely i wouldn't be getting decent tracking. I ran the Assistant 3 times with similar results.

Anyone know whats going on here?
CheersBill

[Startrek]

Do a quick test of your polar alignment
Pick a bright star in the east at 40 to 60 degrees Alt
Slew to and centre it , lock on and then track unguided on that Star , perform an unguided 60 sec sub frame.
Check sub frame zoomed in , if Star is nice and round and not bloated or elongated , eggy etc.. then you PA should be good ( generally good test up to 1200mm focal length which it what I image at with my Newts ) If not , you have some work to do to get your PA error down
Also in PHD2 it’s best to start guide camera exposures at 2 sec or even 3 sec ( not 1 sec, have a read of the manual it’s worth gold ) as 1 sec guide exposures this are too restrictive and can cause you to “chase the seeing” on nights where conditions are not so good.
Just a few things to start with …..

Cheers
Martin

[Ramius]

Hi Martin


Thanks for the response.
Have read, or at least scanned the manual (and a thousand other things in last few weeks) and was aware exposure was too short but had forgotten to adjust.
Good point on an unguided test - will definately give that a go. Subject to other advice was intending to do PA as normal, calibrate and then run Guide Assistant again. If still getting significant PA error will have a crack at a drift alignment.


Still can't believe I could be 4 degrees out but something is clearly off.


Cheers

[phyton42]

Hi Bill. Not that I know much but have been developing my workflow for my Heq5 pro in recent weeks and am using 3PPA in Nina successfully.
I initially set up the tripod leg facing south using a compass or phone and marked the spot on the pavers. Initially I started with 4 degree error. But placing on the marks usually has me with less than 1 degree now. After running 3PPA and a few adjustment runs I get an alignment of 3-5 seconds. Which is well within Phd2 suggestion of 5-10 arc minutes resulting in guiding of 0.7 or better. Having done it a few times now it’s becoming easier. But certainly a learning curve. Let me know if I can help further. Can you post a screen shot of your PA?

[Ramius]

Phyton
A screen shot of the PA? You will have to help me out - I don't know what that means.

[phyton42]

I meant an image/screen cap of the Polar Alignment adjustments/settings.
It may help to see where the error is.
Here’s a recent shot of mine and a 3PPA tutorial.
https://www.youtube.com/watch?v=JI1tzoBhkH8

[Ramius]

Doh.. sorry for being obtuse. I was trying to think of a log that might have that recorded.


Can do but will have to wait for the weather to clear - and error wont be 2 -3 seconds, I am happy around 1 minute.

[toc]

So far I have had no luck with NINA's 3PPA tool. Run it a number of times, and it is still giving 20-30 arc-min of error in PHD2, and Sharpcap.

Sharpcap gives me the best results.

[Ramius]

I still have not had a chance to get outside and do some checks on this.


I don't have much experience to base this on but it seems unlikely that I would get good guiding with 260 degrees of PA error (anyone want to disagree wth that?).


Which would imply the problem lies with PHD2 rather than the Nina 3PPA.


Weather looks poor for another week which is a bit frustrating.