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SEP MultiStar Loses Track of Guide Star

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I have been having difficulties auto guiding with SEP Multi-Star since the 3.5.0 release (it was fine before that). The algorithm repeatedly loses track of the guide star, effectively preventing me from using that algorithm at all. The moment I switch to the Smart algorithm, guiding instantly works and works reliably (even with the same guide star).

Notes:
  • This happens on three different imaging rigs, each with different equipment (though the ASI290MM guide cam is common to all)
  • It happens on Mac (3.5.0) and RPi4-8GB/Stellarmate 3.5.1 (1.5.1)
  • It normally happens immediately after starting calibration, though sometimes it fails closer towards the end of calibration
  • Occasionally, out of 10 tries I will be able to get one through calibration... but it will be unreliable. The guider will routinely lose track of the guide star and will need to restart.
  • As far as I can tell, it is choosing appropriate guide stars most of the time-- not too dim, and not so bright that it clips. Occasionally it will choose a star with a second star in the selection box, though. Also, it is worth noting that occasionally the selection box ends up in what appears to be empty space; not sure if it's trying to guide on a bad pixel, but this only happens rarely.
  • I run 3- or 5-second exposures
  • I tried using dark frames, but as the temperature changes they get invalidated many times a night (might change sensitivity to 5°C)
  • As far as I can tell, I am choosing the proper selection box size (the box is ~2 to maybe 3x wider than the star diameter that is visible in the stretched image; let me know if this is wrong). I have tried different selection box sizes many times with no difference.
  • In essentially every case, the guide star is still in the selection box and is generally well-centered when Ekos loses track of it. "It's right there!" is a frequent exclamation.
  • I am using GA guiding with an explicitly-provided period (400sec for CEM40), but this shouldn't matter as most of the failures happen before guiding even starts. Same behavior if I disable GA
  • Last night's seeing was above average
  • My guide scopes are 120mm and 242mm, both using an ASI290MM. I have tried both 1x1 and 2x2 binning. These cameras are very sensitive, so I don't think it's an issue with low SNR (which is normally 400+)
  • When guiding, I do see RA oscillation where RA will correct positive, then negative, positive, negative, etc. +-1arcsec in each 3-second exposure. No cable drags, wind, etc. I still need to figure this out but thought I'd mention it. I can seem to improve this slightly by severely limiting the max pulse duration when guiding (100 vs 5000) but then when I hit a bigger jump it takes forever to correct. This is worse on the CGX, probably because it is right at its capacity limit (I know, I know, but again, this worked in the past).
  • I have tried resetting to defaults on MANY occasions.
  • I have tried adjusting the calibration pulse length (per the error message's suggestion) from the 1000 default to 500, 200 to no avail.
  • Guide speed is .5 on the CEM40, .85 on the CGX; both are defaults, and set that way in the hand controller
  • Again, this used to work prior to 3.5.0
  • Switching to the Smart algorithm works immediately and reliably, even with the same guide star -- implying a software issue more than an issue with my 3 imaging rigs
Any ideas what I may be doing wrong? I know many, many people are probably using SEP Multistar, so this seems like user error except it A) used to work fine and B) affects 3 rigs on different devices and OSs and versions. Thanks in advance!

Attaching the guide log.
3 years 1 month ago #67013
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Since there have been no responses to this topic, I decided to share what I've learned: According to the developers, the "SEP Profiles" that you can select in the Options > Guide page are new and in need of tweaking. Back when I was troubleshooting this, I didn't see any documentation on the values in each profile but nothing looked awry to me.

I did discover that the "2-AllStars" profile does work for me about 80% of the time. I thought perhaps the other profiles didn't cover the types of stars in my field of view, but this behavior blocked my imaging on two separate imaging rigs with three different telescopes.

Those profiles are not mature for general use, particularly the "1-Guide-Default" profile that is used when you enable SEP Multi-Star the first time. Hopefully one of the developers can test and tweak these more.
3 years 6 days ago #69034

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@MountainAir,

I'm sorry you had issues with this, and I agree with you that:
  • Several of the modules are sensitive to the values in the StellarSolver profiles (focus, SEP guiding, align)
  • There could be better documentation about how to adjust these (though Rob did provide links to SEP documentation in the blue links above the parameters) 
I will say that the guide default parameters, which were my best guess, work well for me and my 105mm refractor with an OAG, and for several other Ekos users--but clearly they don't work for your setups.

My ideal would be that folks learn how to tweak these StellarSolver profiles and post their working profiles, or at least what they changed to make them work, along with their equipment, so that we could all learn how to adjust them. I think some sort of FAQ or WiKi would be best for this type of thing, but perhaps a dedicated forum thread on StellarSolver profiles. There are several threads on this forum which boil down to some issue configuring StellarSolver profiles. On the other hand, when configured properly, the star extraction and align code in StellarSolver work very well.

Before StellarSolver, there was one internal "profile" or way of configuring the SEP star extraction code, and either it worked or didn't work for your equipment (note that "Smart" guiding does not use SEP star extraction, but rather it's own extraction scheme).  Now, Rob has provided a way for users to get things to work for many different kinds of equipment. Unfortunately, it's complicated, and no one is an expert on configuring this yet.

Hy
3 years 6 days ago #69038
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I notice something similar as Mountainair. When I select Multistar, after a few seconds, all other stars except for the main guiding star get unselected again.
The whole process keeps on working though but it looks weird..
2 years 6 months ago #74984

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