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27 Feb 2017
INDI development team is happy to announce the release of INDI Library v1.4.0. This new exciting release builds on the maturity of INDI Library and comes with many new supported devices and fixes for existing drivers. Several improvements and enhancements are included in this release including native support for Cygwin and MacOS platforms in addition to Linux, BSD, and Windows (Client only).
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TOPIC: Reasonable Align Tab Accuracy value for CGEM

Reasonable Align Tab Accuracy value for CGEM 1 week 4 days ago #17281

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Curious, are there any Ekos CGEM users?

What accuracy are you able to achieve with your CGEM?

Going below 60", just does not seem possible for me. If it was not that PHD2 obtaining +/-1" guiding, which I assume is good, I would suspect there was something wrong with the CGEM.

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Last Edit: by maudy. Reason: changed title to point to ekos align tab.

Reasonable Align Accuracy for CGEM 1 week 4 days ago #17283

I use EQ6 and can comfortably achieve under 0.75 arc second if its not windy using the Ekos internal guider. Depending upon where in the sky your imaging you may need to tweak the guiding settings a few times to establish a reliable performance for that position. As with all guiding, polar alignment, scope balance and bias weight is key to optimum performance.

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Skywatcher 190MN - EQ6 Pro - ASI1600MM-Cooled - EFW7 - ASI120MM - WO f4 Guide Scope - Rigel nStep - Ekos chained to two Raspberry Pi 3's - KDE Neon - PixInsight

Reasonable Align Accuracy for CGEM 1 week 20 hours ago #17323

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I wrote my question too quick at the end of a imaging session.

My balance and polar align is something i am working on to make the PHD2 guiding better. With the +/-1" peak to peak though, it suggest to me that the mount performance is doing okay. This is my guess though as I am still learning.

What I am trying to understand is the plate solving accuracy folks are getting with CGEM, Ekos and astrometry plate solving. Sorry I was not clear in the original question. Lesson learned, and I will wait for my head to be more awake before posting.

On the Ekos Align tab, the default is to centre within 30". I have only achieved this once. It was after a HC reset, realignment with two star align on the CGEM, immediate slew to target and then plate solve.

Typically though I need to set this to 60" accuracy on the Ekos Align tab. The CGEM just does not seem to want to slew any closer, once it is within 60" it can solve 12 times and not get closer. It would be great to get the accuracy as small as possible so the guidestar used can be near the same night after night.

I have been having setup issues getting all the things talking correctly, and think things are nearly there. Perhaps 60" makes sense at F/10 2800mm focal length for my C11. The 60" though seems to mean that I can miss the guidestar with my OAG and guide camera.

Are CGEM users able to use Ekos' align tab and, reliably within 2-3 solving, get below 30" centring?

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Reasonable Align Accuracy for CGEM 1 week 6 hours ago #17326

The plate solver works very well with an image containing distinctive stars. In my experience it doesn't like solving around the NCP, nor deep inside the Milky Way, nor does it like globular clusters. I tend to slew East to somewhere around 45 degrees for my first solve, then another two on the same side in a triangle from the first. Once the scopes starts to be more accurate I delete the earlier solves (the one's not centered in the plot graph) and continue with more stars until each slew is perfect.

After I've done this (which takes a handful of minutes) I will then use the Polar Alignment Assistant tool to double check my mount alignment. If it is indeed out (a major contributor to poor guiiding) I will of course manual adjust my mount using the PA Assistant (sometimes needs to be done twice) and then restart the start alignment/plate solving.

Note: If I move to other side of sky I will again solve at least another three stars, again deleting the ones that don't fall in the centre.

IMPORTANT: just in case, save the mount model as you progress.

Start to finish this is 20minutes. The most valuable 20min you'll ever spend in an all night session.

After this your guiiding can now be set up. Try it with the built in guider first and, should you prefer, PHD2 after. Both guide applications will need a few tweaks to the setup parameters (Max and Min Pulses) is where the magic happens.

Note: I frequently attend imaging evenings with a CGEM owner. He doesn't use Ekos (yet) and simply uses the hand controller to set up his two/three start alignment before using PHD2 to guide. His guiding is either great or horrid depending upon his physical polar alignment at setup. The PA Assistant is a brilliant tool and with the subsequent accuracy of polar alignment, it's your new guiding BFF.

Mount Mechanical Problems: One accurately polar aligned if you are concerned about mount error then log the Guide Data. This will produce a text file that can be exported into a spreadsheet to visualize possible mechanical errors. The guide data log gives you an insight only, you will need to use some dedicated mount software to fully evaluate mechanical errors.

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Skywatcher 190MN - EQ6 Pro - ASI1600MM-Cooled - EFW7 - ASI120MM - WO f4 Guide Scope - Rigel nStep - Ekos chained to two Raspberry Pi 3's - KDE Neon - PixInsight

Reasonable Align Accuracy for CGEM 6 days 20 hours ago #17328

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Interesting, typically it is the CGEM modelling I use, and have found it very accurate. The Precise Go-to is nice.

I had not consider attempting to model with Kstars, and had assumed if KStars instructed the CGEM to go to coordinates, the CGEM's model would be able to do so.

Perhaps the CGEM should be aligned with one star only (assuming a good polar alignment) and then Ekos' modelling should be done for the remainder of the session

i.e. Align CGEM with hand controller as close as possible to one star, then use Ekos to align the same start, then sync CGEM on the aligned star. After this use the Ekos solver to align the star/target, or perhaps align a triangle in the sky.

Make sense?

Question:

1. Is there any residual from the KStars sync's left, or needing removal, on the CGEM? Anything that would require reseting the CGEM, such as a Sync on the CGEM or perhaps an undo sync?
2. How much of the previous solves in the Ekos molding should be kept?

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Reasonable Align Accuracy for CGEM 6 days 6 hours ago #17331

I presume your setup is not permanent and therefore when you setup before each session you are assembling the tripod, mount and scope. Having witnessed a CGEM being set up and used, guiding is noticeably better when time is spent on mechanical polar alignment i.e. level tripod and accurate inclination (altimuth). What KStars offers, with its Polar Alignment Assistant, is a precision RA alignment. Get that spot-on and your guiding performance will improve with less pulses and possibly little if any DEC movement. Precise polar alignment will also allow you to accurately model/expose your mechanical errors, if any. Using the Polar Alignment assistant will give you the confidence enjoyed by owners of permanently mounted rigs.

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Skywatcher 190MN - EQ6 Pro - ASI1600MM-Cooled - EFW7 - ASI120MM - WO f4 Guide Scope - Rigel nStep - Ekos chained to two Raspberry Pi 3's - KDE Neon - PixInsight

Reasonable Align Accuracy for CGEM 4 days 13 hours ago #17356

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Thank you I will check the polar alignment next time.

It is not clear to me if it will allow the Align Tab's solve and slew to get reliably closer than the 60" accuracy, even doing the 30" default would be nice.

I can report back as soon as skies clear. Things are unusually over cast for months with spotty nights once every 2 weeks.

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Reasonable Align Accuracy for CGEM 4 days 10 hours ago #17361

Just a thought; is your FOV correct for your scope and camera combination?
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Skywatcher 190MN - EQ6 Pro - ASI1600MM-Cooled - EFW7 - ASI120MM - WO f4 Guide Scope - Rigel nStep - Ekos chained to two Raspberry Pi 3's - KDE Neon - PixInsight

Reasonable Align Accuracy for CGEM 2 days 3 hours ago #17390

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I believe so, the astrometry files are the recommended, and some smaller ones were just added in case it can help resolve faster.

As things seems to work, the FOV was not directly calculated. I will double check.

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