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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Delta RMS Threshold

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Delta RMS Threshold was created by Phil

I've been chatting with a friend remotely while he shoots, and says he keeps getting an error in the Ekos guider stating "Delta RMS threshold value exceeded. Searching for guide stars..."

He's tracking with a SkyWatcher Star Adventurer via ST4, using an ASI120MM Mini camera. He took a pic of his error that you can see below.

So what exactly does this message mean?

Thanks
1 year 8 months ago #84420
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Replied by Lenny on topic Re:Delta RMS Threshold

There is too much variation while trying to guide. Leading to large corrections and the error between where it is and where it needs to be is too large.
Possible due to incorrect polar alignment.
This was my biggest nemesis when I started out.


Sent from my iPhone using Tapatalk
1 year 8 months ago #84431

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Replied by Phil on topic Re:Delta RMS Threshold

Taking your information into account, we've surmised that the mount is overloaded and losing track, causing the guider to over-correct, making the entire situation worse.

Thanks for your reply.
1 year 8 months ago #84443

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Replied by Chris Kuethe on topic Delta RMS Threshold

I'm seeing this too, but very irregularly. Last night I was tracking and guiding for hours at about 1/2px accuracy. Tonight, after a while suddenly my guiding goes completely out to lunch... and just as suddenly stabilizes again.
2022-07-25T22:10:03 Capturing 240.000-second LXtreme image...
2022-07-25T22:10:03 Job requires 240.000-second LXtreme images, has 5/15 frames captured and will be processed.
2022-07-25T22:10:03 Guiding deviation 0.214 is now lower than limit value of 6 arcsecs, resuming exposure.
2022-07-25T22:09:55 Guiding deviation 41.911 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:52 Guiding deviation 50.187 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:51 Guiding deviation 51.030 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:48 Guiding deviation 56.015 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:45 Guiding deviation 59.776 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:41 Guiding deviation 62.828 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:38 Guiding deviation 53.691 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:34 Guiding deviation 36.528 is still higher than limit value of 6 arcsecs.
2022-07-25T22:09:32 CCD capture suspended
2022-07-25T22:09:32 Guiding deviation 25.124 exceeded limit value of 6 arcsecs for 3 consecutive samples, suspending exposure and waiting for guider up to 60.000 seconds.
2022-07-25T22:07:04 Capturing 240.000-second LXtreme image...
2022-07-25T22:07:04 Job requires 240.000-second LXtreme images, has 5/15 frames captured and will be processed.
2022-07-25T22:07:04 Guiding deviation 0.928 is now lower than limit value of 6 arcsecs, resuming exposure.
2022-07-25T22:06:56 Guiding deviation 96.370 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:55 Guiding deviation 94.288 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:52 Guiding deviation 84.705 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:51 Guiding deviation 76.812 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:47 Guiding deviation 60.596 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:44 Guiding deviation 45.056 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:43 Guiding deviation 37.798 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:40 Guiding deviation 25.648 is still higher than limit value of 6 arcsecs.
2022-07-25T22:06:39 CCD capture suspended
2022-07-25T22:06:39 Guiding deviation 19.861 exceeded limit value of 6 arcsecs for 3 consecutive samples, suspending exposure and waiting for guider up to 60.000 seconds.
2022-07-25T22:05:26 Capturing 240.000-second LXtreme image...
2022-07-25T22:05:26 Job requires 240.000-second LXtreme images, has 5/15 frames captured and will be processed.
2022-07-25T22:05:26 Guiding deviation 0.212 is now lower than limit value of 6 arcsecs, resuming exposure.
2022-07-25T22:05:18 Guiding deviation 95.419 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:17 Guiding deviation 96.264 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:13 Guiding deviation 102.797 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:12 Guiding deviation 102.578 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:09 Guiding deviation 87.803 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:08 Guiding deviation 67.057 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:05 Guiding deviation 37.372 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:03 Guiding deviation 27.406 is still higher than limit value of 6 arcsecs.
2022-07-25T22:05:01 CCD capture suspended
2022-07-25T22:05:01 Guiding deviation 15.088 exceeded limit value of 6 arcsecs for 3 consecutive samples, suspending exposure and waiting for guider up to 60.000 seconds.
2022-07-25T22:01:11 Capturing 240.000-second LXtreme image...
2022-07-25T22:01:08 Captured /home/stellarmate/Pictures/Light/LXtreme/C27_Light_LXtreme_240_secs_2022-07-25T22-01-09_005.fits
2022-07-25T22:01:08 Received image 5 out of 15.
2022-07-25T22:01:08 Download Time: 0.86 s, New Download Time Estimate: 1.09 s.
2022-07-25T21:57:07 Capturing 240.000-second LXtreme image...
2022-07-25T21:57:04 Captured /home/stellarmate/Pictures/Light/LXtreme/C27_Light_LXtreme_240_secs_2022-07-25T21-57-06_004.fits
2022-07-25T21:57:04 Received image 4 out of 15.
2022-07-25T21:57:04 Download Time: 1.56 s, New Download Time Estimate: 1.14 s.
2022-07-25T21:53:03 Capturing 240.000-second LXtreme image...
2022-07-25T21:53:02 Dither complete. Resuming in 1 seconds...
2022-07-25T21:53:02 Dithering succeeded.
2022-07-25T21:52:51 Dithering...
2022-07-25T21:52:51 Captured /home/stellarmate/Pictures/Light/LXtreme/C27_Light_LXtreme_240_secs_2022-07-25T21-52-52_003.fits
2022-07-25T21:52:51 Received image 3 out of 15.
2022-07-25T21:52:51 Download Time: 1.22 s, New Download Time Estimate: 1.00 s.
2022-07-25T21:48:50 Capturing 240.000-second LXtreme image...
2022-07-25T21:48:47 Captured /home/stellarmate/Pictures/Light/LXtreme/C27_Light_LXtreme_240_secs_2022-07-25T21-48-48_002.fits
2022-07-25T21:48:47 Received image 2 out of 15.
2022-07-25T21:48:47 Download Time: 0.84 s, New Download Time Estimate: 0.89 s.
2022-07-25T21:44:46 Capturing 240.000-second LXtreme image...
2022-07-25T21:44:44 Captured /home/stellarmate/Pictures/Light/LXtreme/C27_Light_LXtreme_240_secs_2022-07-25T21-44-44_001.fits
2022-07-25T21:44:44 Received image 1 out of 15.
2022-07-25T21:44:44 Download Time: 0.94 s, New Download Time Estimate: 0.94 s.
2022-07-25T21:40:42 Capturing 240.000-second LXtreme image...
2022-07-25T21:40:42 Job requires 240.000-second LXtreme images, has 0/15 frames captured and will be processed.
1 year 8 months ago #84672
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Replied by Phil on topic Delta RMS Threshold

What mount are you using? Are you well balanced and within the mount's weight capacity? We believe the problem with the Star Adventurer was that it was overloaded and mistracking, causing the guider to autocorrect, probably making the situation worse. We have yet to try and confirm this with a lighter load.
1 year 8 months ago #84697

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Replied by Chris Kuethe on topic Delta RMS Threshold

Me? AZ-GTi. Yep, I'm very well balanced. Bearings are all cleaned, polished, and greased. Cables are managed such that there are no snags (almost learned that the hard way once). It's not a periodic or regular occurrence for me either, just every now and then guiding seems to get very lost (and not because of clouds) for a couple of minutes, and then suddenly settles down.

Here's the rest of my guiding from last night.
1 year 8 months ago #84711
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Replied by Phil on topic Delta RMS Threshold

What kind of load is on your rig? Are you at the halfway point, or at, or surpassing, the load limit? My friend was over capacity on the Star Adventurer. We think think that's the problem. Also, did you polar align using Ekos?
Last edit: 1 year 8 months ago by Phil.
1 year 8 months ago #84715

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Replied by Chris Kuethe on topic Delta RMS Threshold

4kg, not over limit. Polar aligned with ekos. It seems quite unlikely to me that it's a mechanical issue, given that it's not continuously bad or jerky tracking, nor is it only at a specific pointing angle. In fact, most nights I don't see this at all.
1 year 8 months ago #84720

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