Outliers during guiding

[Hy Murveit]

Hi Marcin,

FYI the particular SNR isn't important as long as it's "high". It's the
ratio of the guide stars' brightness to the background. If you change guide
stars then it might change.

Your plots look like some mechanical issue, whether it's a snag or bump or
something moving on your setup. Also, your long-term RMS isn't as important
as the RMS during a particular image. Once the blip leaves the length of
the RMS-history-calculation, the RMS improves.

What l like to do is look at things in Analyze, and if you want click on a
particular capture and you can see the guiding scatter for that image and
the RMS values for that image. I kind of doubt the guider intentionally
tried to move the scope, but if you had the log file and had guiding
logging enabled, we could tell--you could probably figure that out by
looking at the logs too.

Make sure you are using multi-star guiding.

Hy





On Sat, Mar 14, 2026 at 1:40 AM Marcin Owsiany <marcin at owsiany.pl> wrote:

> Hello,
>
> Tonight ekos (kstars 3.8.1) was happily guiding SNR of ~98 and steady RMS
> of ~0.75'', when on a couple of occasions, the guide star was observed to
> suddenly jump 110-185'', combined with a similarly rapid drop of SNR to the
> level of 11 or 44.
>
> I wasn't looking at the captured frame at that moment, so I don't know
> whether this was indeed a jerk, or rather a satellite streak or similar.
>
> The situation recovered immediately on the next capture, or the one after,
> but the average RMS was completely destroyed for the following 7 minutes or
> so.
>
> See screenshot:
>
> [image: guiding.png]
>
> I guess it would make sense to change ekos to somehow skip such sudden
> long-distance moves combined with sudden SNR drops? Currently the
> compensating pulse it sends just makes things worse.
>
> regards,
> Marcin
>
> BTW the SNR reported in the on-hover popup has units of arc-seconds ('') -
> is that intentional?
>
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