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INDI Library v1.9.3 Released (11 Nov 2021)

Bimonthly Stable INDI Library release introduces new drivers and fixes for existing ones. Some highlights:

Can meridian flip be set before reaching meridian? Scope hits mount at zenith.

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I've been using Stellarmate / Kstars to run my observatory and I'll admit that I'm a newbie to this system as well as the GEM mount. I recently went from a LX200 wedge to an EQ6R-Pro. I have a 12x12 plate on my pier which I mounted my new mount on top of, but finding that the corners stick out a bit too much and the scope contacts the corner and gets stuck. Fortunately, the EQ6R seems to have a clutch that prevents damage to anything, but obviously I need to avoid this!

Reading the HA> settings in the Capture module, from what I understand the setting is where the mount will flip at a certain hour/degrees <em>past</em> the meridian? I read a posting here about the HA setting and maybe I'm misunderstanding how that works. What I would like to do is set a flip somewhere before it reaches this corner of the mount, but a bit confused about the settings on this. I will have to either raise my mount a few more inches or maybe add a spacer at the scope/mount clamp, but I think that may still cause a problem, but just delay it a few minutes. I'll add the mount raising to my spring list of fixes, but for now I'm hoping there is a setting that can flip it before this happens.

Ideas?

Thanks!
Tom
Last edit: 1 year 11 months ago by Tom Gwilym.
1 year 11 months ago #47392
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As you have seen at present Ekos doesn't allow a flip to be attempted until the meridian. It would be trivial to modify Ekos to allow a flip before the meridian - just allow the minmum flip hour angle to be negative.

But there are several snags:
First, all that happens when the flip is commanded is that the mount is slewed to the position it is currently pointed at. The mount would have to be set internally so that a slew command before the merdian caused a flip. Some mounts can do this, the Celestron mounts have a meridian mode that can be set to prefer West and this will cause the mount to flip up to 20 degrees before the meridian. The flip limit can be set by setting the Ra limit. I don't know about others.
Second, if a slew is commanded just before your scope hits the pier will the corresponding position on the other side of the pier be reachable? Or will you have changed your scope tracking into the pier problem to a scope flipping into the pier problem?

If your scope actually has a zone near the meridian that can't be reached then the solution you need would have to do something like stopping tracking before the mount reaches the meridian, waiting until the target position is sufficiently past the meridian, completing the flip and continuing.

Maybe the completion time could be used to at least stop the scope hitting the pier - and perhaps a second sequence with a start time be used to continue after the target is clear of the pier. The times might need to be adjusted every day.

I don't suppose you can take a hacksaw to the plate? Sometimes hardware solutions are easier than software, esecially for a one off. Or choose target declinations that don't go into the pier.
1 year 11 months ago #47400

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Another "hardware" style solution - put a riser under your scope mounting point to the mount saddle to move it out further.

I doubt the scope is that heavy that moving it further away from the centre would hurt.
1 year 11 months ago #47401

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I'm not doing any totally automated imaging, but just controlling it from in the house. I may just have to avoid the zenith carefully for now, then work on a hardware fix. I originally had an LX200 Wedge on the 12x12 plate, but recently did a full change to a new mount and new scope. Raising it would be the best answer. I was just hoping there was a possible workaround for it that wasn't too complicated. Seems the closest I could do is to set the HA> 0.00 then it will flip at the meridian (or as close as possible).

Here is my mount showing the plate.
Best thing to do would be to raise the EQ6R a few inches.

Last edit: 1 year 11 months ago by Tom Gwilym.
1 year 11 months ago #47405
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Adding a riser is my best plan. I could put a saddle to put the scope out a little farther, but I think another 10 inches higher would be the best fix, then it could swing a little underneath before the flip.
1 year 11 months ago #47406

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Yes I think you are right. Even if the adaptor plate was gone the mounting lugs on the pier will probably be in the way.
Or avoid declinations that give the problem, a lower dec would miss the pier.

I think this illustrates the need for more management of how the system copes with what goes on at the meridian. I'll post my more general thoughts on that separately.
1 year 11 months ago #47418

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Cutting those corners would require another trip to the metal shop for a redesign. I think it's probably just those two corners on the east/west that would be the conflict. I'm still new at the GEM mount, with a long telescope vs. the stubby SCT I went from! I'll start staring at my plate and come up with ideas to raise it. It does have a bunch of holes in it already from the wedge, so I can easily mount something. Probably 10 inches higher would solve my problem.
1 year 11 months ago #47452

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