10micron mount slews appear to complete but the mount drifts for many seconds

[Manoj Koushik]

I have a 10 micron 3000 mount and have been noticing two issues and hoping someone can shed some light on why this might be happening.

[edit: thread split, second part in this thread]

Issue #1: After a sizeable slew,the first image of the target always has star streaks. The same target is fine (stars are round) on subsequent exposures and note that there is dithering happening in between. These are unguided exposures, so it looks like dither happens through small slews. The mount is running a 98 point model and my suspicion was that this is because of the mount having to apply the model post slew to begin tracking, which is probably more time and compute intensive on bigger slews that happen for target acquisition than that of a few pixels that happens for dither (mount is pretty much in the same spot of the sky). I tried setting mount settling time to 20 seconds in ACP and that did not seem to fix the issue. So instead I registered UserActions.wsc and added a 20s delay in SlewEnd(). This made the stars better. Increased it to 30s and the stars got even rounder (still a small streak). Next I am thinking of increasing it to 40s to see if that resolves the issue. Unfortunately, this delay ends up effecting those dither slews as well and makes everything slow. Wondering if there is a better way of doing this. I could modify AcquireSupport.wsc to pass c_SlewDist to SlewEnd so that I do the delay only on big slews (> 3.0 degrees). But hesitant to change up AcquireSupport. Has anyone else seen this and fixed it another way?

BTW is there any way to get Scheduler out of operator intervention without having to shut it down and restart it?

[Manoj Koushik]

On issue #1 adding a delay in slewend does not really seemed to have worked unfortunately. I increased it to 40s and I still notice oblong stars on the first image. I also realized that my earlier theory was wrong because after the slew, ACP does do a dither even for the first image. So it cannot have been the slew itself. It could be the dither, but if that was the case I would notice issues on all the images in the plan. But I only notice it on the first image. I am at a loss on why this might be happening! Right now I am having to discard one image from every plan that scheduler is submitting to ACP which is incredibly wasteful

If anyone else saw this and found a solution I would love to hear, please.

[Bob Denny]

This sounds like a software victory over hardware, always a sub-optimal approach ha ha. What does 10 Micron say about this? Even more disturbing is the fact that ACP thinks it has finished slewing, yet it clearly has not, and you are applying an open loop delay post-slew. ACP will not proceed after a slew until the mount says Slewing = False. I would definitely start with a support ticket with 10 Micron. This isn't right and I haven't heard of it from anyone else. Maybe a search on Cloudy Nights will yield a clue.

[Manoj Koushik]

I am going to reach out to them as soon as I have more concrete data.

I should point out that I was also erroneous in my previous statement.

Yesterday night I had a good run with 4 targets capturing data for almost 8 hours.

I now realize that all the other targets were good even on the first image and that I only noticed this issue with two particular projects I have: Trifid Region and Swan region. Both of which are low on the horizon.

So might have something to do with the altitude. But again, still a mystery on why it only happens on the first image acquired for the target sequence plan.

Tonight I am hoping I will have many targets as well. I can then capture crops from all of the targets (first image and second image) and then reach out to Ed/10Micron.

[Manoj Koushik]

Long overdue response. This seems to be related to the declination of the object. I have about .36' of polar error which combined with the 1800s subs contributed to this. We can consider this one closed out as well.

[Bob Denny]

OK, will do and thanks very much for getting back!!