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

Bi-monthly release with minor bug fixes and improvements

Meridian Flip Configuration

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I had my mount model very screwed up. I think I have it working correctly after going to the defaults, going to park and releasing the RA clutch to get the counterweight bar vertical. Now when the scope slews, it appears to be pointing in the right place plus the hour angle on the Ekos mount tab is consistent with the KStars hour angle.
4 years 1 month ago #49519

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Here is a follow-up from a more-or-less successful evening.

I was working on M42 and did a solve and slew at HA ~+1minute. The mount was on the west pointing east at the start of the solve and moved to the east side. However, it would only slew to Alnitak or Alnilam at this point in time (consistent with the display in KStars). After playing around on the Horsehead Nebula (not sure how long), I could successfully move to M42.

Any suggestions?
4 years 1 month ago #49878

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Last night while... ahhh making my normal, non-sleeping walk down the hall :whistle: , I checked my phone to see how close I was to a flip. I noticed a nice timer message counting down on the , which I hadn't noticed before.

Later after another trip (yeah, I'm getting old)... I saw in my yard cam that the rig did do the flip. Plus that message said Status: Inactive

My thoughts are, as long as that count-down message is running, it will flip.

Here's the simulator showing the same thing:
The following user(s) said Thank You: Craig
Last edit: 4 years 1 month ago by David Tate.
4 years 1 month ago #49883
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I think you missed my point. I didn't call for a switch in direction. I only commanded a solve and slew. I didn't look at the hour angle until after the slew took the mount to the east side.
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4 years 1 month ago #49884

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Any slew that is done when the mount prefers to be on the other side of the pier will do a flip.

All that the pier flip process does is wait until the flip condition is reached, then does a slew to the current coordinates.
4 years 1 month ago #49889

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It's OK that the flip occurred. The issue is it wouldn't then go to the target (M42). The actual (not the desired) behavior was replicated in KStars. I would think that if the logic says we need to flip that it would then go to the target, not just somewhere close.

The capture and slew and, if I recall correctly, a load and slew did not go to M42 at that point in time. Several minutes later (didn't make note of the actual hour angle), it finally would go to the target.
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4 years 1 month ago #49899

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It goes to the same coordinates. Where that is 'on the sky' depends on the quality of your pointing model. So usually it does a solve-and-slew round after flip, if the flip was initiated by EKOS. If it does the flip because it hit the mounts setting limit, this of course doesn't happen, and you are left with the accuracy of your pointing/alignment.
4 years 1 month ago #49903

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Normally it's possible to reach any position from one side or the other of the pier and it is possible to track a reasonable distance past the meridian. I'm not sure that all of this applies to your mount and you have a very small range where you can reach an object wth the mount on either side of the meridian. It may even be that there is a zone which can't be reacked at all.

As Der Pit says pointing errors may make your mount point differently when the pier side is changed. Ekos will usually do a solve and sync after a pier flip, at least when it's imaging.

As I said before I don't think there's anything in Ekos to manage hour angle limits, at least at present.

i'm not sure how much we can help though, we can't see your mount and so can't see much of what is needed to help you work out what is going on. A few lines of social media posting doesn't give us much. The result is confusion, misunderstanding and misinformation.
4 years 1 month ago #49905

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Are you saying my mount model is reflected in KStars? When the mount slewed to Alnitak instead of M42 and plate solving said I was on target, I looked at KStars to see where it thought I was pointing and it indicated Alnitak. I selected M42 in KStars and told EQMod to slew to M42 and it wouldn't move there.

When it wouldn't move to M42, I went to the Flame Nebula in KStars and told EQMod to slew to it. The slew showed properly in KStars, staying on the east side, and plate solving showed I was very close to the target. It took about the usual amount of fine moves to get the mount centered on the target within the tolerance I had given.

I have attached the log from this particular session for additional information. I think the issue starts around line 439150, local time 21:21:30.

File Attachment:

File Name: log_17-19-02.zip
File Size:7,516 KB
4 years 1 month ago #49914
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Uh, that sounds weird indeed.
Could it be that you had moved the KStars FOV (not the mount pointing) at some point after having slewed to M42, so that EKOS/the align module thought that was the target?
Also, if you look at the log, the messages from align only start around 21:34, so before there seems to not have been a try to actually do an alignment....
(Edit: and the coordinates refered to there are the ones of M42)
Last edit: 4 years 1 month ago by Peter Sütterlin.
4 years 1 month ago #49917

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Look at line 146277 which shows the mount is on target for M42 at 19:27:54(+) local time. This was on the west side of the pier. I realigned at 19:52 (194825), 20:00 (276814) and 20:18 (311291). At 20:18, the accepted solution is about 2 minutes in declination from M42 (which isn't Alnitak either). I'm still confused....
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4 years 1 month ago #49918

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2 arc minutes in declination away is very close after a meridian flip and if you mean 2 minutes of time then it's still only half a degree which is still not bad.
4 years 1 month ago #49928

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