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Question Avalon Linear Guiding Optimisation

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24 Apr 2020 23:04 #231 by Hugues
Avalon Linear Guiding Optimisation was created by Hugues
Hello,

I'm am an happy user of the avalon linear (stargo) since a couple of years which was a real improvement of my previous AZEQ6 mount ;)
But i'm seeking advice for a better guiding.

This guiding is not bad at all and under the pixel, but i struggle with some excentricity >0.6 with my FSQ106ED.
I always test the mount balance in many direction.
But, on average night my RA RMS is always near the double or more than the DEC value.

I usually guide with 3sec exposure to average the seeing, and guiding with smaller guide exposure doesn't help to much (just more oscillations)

Does anybody have some idea/method on reducing this diff between RA and DEC on the Avalon Linear ?
Did i need to do some maintenance on this mount ?

here is an exemple:
RA RMS: 0.72" (0.11px)
DEC RMS: 0.31" (0.05px)
RA PEAK: 1.65" (0.25px)
DEC PEAK: 1.07" (0.17px)

Here is my PHD2 guiding parameters:

Guiding Begins at 2020-04-15 03:12:53
Equipment Profile = LoadstarX2-OAG
Dither = both axes, Dither scale = 1.000, Image noise reduction = 2x2 mean, Guide-frame time lapse = 0, Server enabled
Pixel scale = 6.46 arc-sec/px, Binning = 2, Focal length = 530 mm
Search region = 15 px, Star mass tolerance = 50.0%
Camera = SX Lodestar, full size = 376 x 290, have dark, dark dur = 2500, no defect map, pixel size = 8.3 um
Exposure = 3000 ms
Mount = Avalon Mount (ASCOM), connected, guiding enabled, xAngle = -95.2, xRate = 0.785, yAngle = -4.1, yRate = 0.760, parity = +/-
Norm rates RA = 5.7"/s @ dec 0, Dec = 4.9"/s; ortho.err. = 1.1 deg
X guide algorithm = Lowpass2, Aggressiveness = 75.000, Minimum move = 0.000
Y guide algorithm = Lowpass2, Aggressiveness = 50.000, Minimum move = 0.020
Backlash comp = disabled, pulse = 20 ms
Max RA duration = 500, Max DEC duration = 500, DEC guide mode = Auto
RA Guide Speed = 4.5 a-s/s, Dec Guide Speed = 4.5 a-s/s, Cal Dec = 27.0, Last Cal Issue = None, Timestamp = 4/15/2020 1:09:22 AM
RA = 17.34 hr, Dec = 57.9 deg, Hour angle = -2.75 hr, Pier side = West, Rotator pos = N/A, Alt = 64.2 deg, Az = 53.6 deg
Lock position = 91.481, 132.671, Star position = 91.481, 132.671, HFD = 2.79 px

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25 Apr 2020 14:41 #232 by mpoelzl
Replied by mpoelzl on topic Avalon Linear Guiding Optimisation
Hello!

I'm no expert but I think you need to be a lot more aggressive. Here are the suggested settings from Avalon:

www.avalon-instruments.com/support-2/tro...suggested-parameters

Mike

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25 Apr 2020 17:17 #235 by Hugues
Replied by Hugues on topic Avalon Linear Guiding Optimisation
As i said i've reduced the agressiveness in RA from 90 -> 70 to avoid oscillations.
I've also tried to crank up the RA speed to 0.5x with à tiny improvement on RA.
The DEC seems OK even at 50 !

Guiding at the recommended 1 sec is technically possible with a lodestar and the OAG, but it's guiding result very sensitive to seeing condition and altitude of the target.

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25 Apr 2020 17:45 #236 by mpoelzl
Replied by mpoelzl on topic Avalon Linear Guiding Optimisation
Maybe you have tried this already but with my FSQ85 I use the Hysteresis guide algorithm on both axes as that worked best for me (with aggressiveness of 95).
Mike

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26 Apr 2020 18:20 #237 by Hugues
Replied by Hugues on topic Avalon Linear Guiding Optimisation
I've tested this method yesterday night without improvement.
What i love about this avalon linear mount is it's consistency. And the repetable guiding result achevied on different nights ;)

I've a decent guiding, but i always struggle to get a round scatter :(

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27 Apr 2020 12:50 #242 by Michel
Replied by Michel on topic Avalon Linear Guiding Optimisation
Don't worry about it as long as you're getting round stars. Why are you binning your lodestar? it's already undersampled with 1x1 and your focal length.

Stay on on lowpass 2, increase RA agg to 90, max ra to 1000 and see if it is more responsive to RA. There is in stargo ajd RA tracking automatically, you might want to try that as well, it might improve your RA further.

Also try to manage with exposure 1 or 1.5s if possible. try RA/DEC guiding rate at 0.2, 0.3 and 0.5 (recalibrate each time) and see which works for you.

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