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INDI Library v1.9.7 Released (29 Jul 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

Polar Alignment Assistant your results?

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Hi
I just wondering what are your best results with EKOS Polar Alignment Assistant, and what results do you think are sufficient for a good session?

I had a previous session where I was able to get down to 20'' (8x50 guide scope, ASI174MM Mini), but my last session was ~5'. What is your limit where you would re-do an alignment?
--= human, without Windows™ =--
pls excuse my bad english! :)
4 years 2 months ago #26127

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It depends on your setup. How long a focal length are you imaging at, how accurate is your guiding, and how long you are exposing for. A couple minutes off isn't bad, but if you are imaging at a long focal length and long exposures, under 30" is excellent. If you are too far off, even with good guiding you can still get frame rotation in long exposures with inaccurate PA.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
4 years 2 months ago #26130

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Ok, thanks, I will try to keep the error below 2' or so. My exposures are usually currently not above 120 secs and my focal length is 547mm, so no very big magnification.
--= human, without Windows™ =--
pls excuse my bad english! :)
4 years 2 months ago #26154

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That is a somewhat forgiving focal length. 2' should serve you well.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
4 years 2 months ago #26157

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Hi,

I'm attempting to get my polar alignment results more consistent between imaging sessions. Yesterday my polar alignment results varied wildly.
Between iterations, I went from 5arcminutes to 24arcminutes regardless of whether I clear the alignments solutions between iterations.

My best result so far was 58arcseconds (see attachment). I have not been able to reproduce this or get anywhere under 1arcminute since.
My mount is a Celestron CGE which has had the Azimunt adjustment bolts upgraded and a beefy Altitude knob.

The largest variations occurs when the polar alignment routine crosses over the meridian in the north. Has anyone experienced this?
Many thanks in advance.
4 years 1 month ago #26873
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Perhaps check for sources of differential flecture in your guide scope. Make sure evening is tight. Maybe don't bin the frames either.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
4 years 1 month ago #26874

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Thanks Ihoujin.

1. Differential flexure is not an issue (i think). 6 point guide scope rings bolted onto a dovetail bar which are in turn bolted be three M6 hex screws onto a losmandy plate.
2. Evening is tight? I don't understand sorry.
3. I've been binning 2x2 so will try unbinned.

I read on the forums here somewhere that cone error should not be an issue with the PAA routine. Would it help to bring the guide scope I'm using lower to the mount?

Currently I have the 50mm guidescope on top of a GT81 refractor which is on top of an ED120 refractor. So all in all it's about 230mm above the Mount's saddle plate.
Thanks.
4 years 1 month ago #26875

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Cone error is not a concern, is it all still sharing the same common axis of rotation.
All i meant by tight, is to check that the screws haven't come loose.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
The following user(s) said Thank You: Wilson Muchenje
4 years 1 month ago #26876

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I'll post update from my next session. Thanks for taking time to respond.
4 years 1 month ago #26878

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