Manual Meridian Flip not working #mesu


SIMON
 

hi,

I have the Mesu e200 MKII GEM and because of work-arounds for the 'track past meridian bug' often when I go-to an object the mount points with the weights up, often meaning the object is obscured by hedges etc.

I thought I could simply go to 'features' | 'Do a GEM Flip'  but this just moves the mount about 10-15 degrees and then stops. the only way I can get the mount to go-to correctly (mounts down) in this situation is to manually move the mount using the hand controller so it is in the correct orientation and close (very rough) to the object, then when I perform a goto it slews the short distance needed to point to the object with the mount in the correct orientation.

Obviously this makes it impossible to operate the telescope from my warm room or remotely from the house (and is very frustrating) 

Is the 'Do a GEM Flip' a bug of have I misunderstood what this button should do?- and is there an ETA for fixing the original problem (https://groups.io/g/Sitechservo/topic/87338280#33935 )

I have a video that shows the behaviour here -https://www.youtube.com/watch?v=RlB6eaodgHA this is unlisted you can only view it from this link.
here are the mount param settings


Thanks in advance.
Simon.


Don W
 

Hi Simon,
Your attached images of Mount Parms are confusing.  If you use settings of 45 degrees for meridian limits, then you will have the problems you described.  The way to fix them is to use the settings in your attached images - about 2 degrees meridian limits for over pole and 178 degrees for under pole.

Don W


MartinC
 

Hi Don,
Hope you had a good Christmas & New year?

I too have experienced the same behaviour as Simon during my attempts to find a 'work-round' for the fact that the track-past in GEM mode is mandatory. As you know from our previous correspondance I too have tried all manner of meridian limits. All to no avail. This is all recorded in previous posts & emails between us so there's no point in repeating myself.

I've had my Mesu e200 MKII for a year now and very quickly discovered & reported the track-past situation. Simon & I are singing from the same hymn sheet. One other Mesu customer has also raised the same point on this group. I also know of a 4th person who also finds this frustrating.

It's not so much a 'bug' but something that really seriously does need amendment. Something along the lines of replacing the “GEM Auto Flip Track” check box with 3 radio buttons instead.

  1. Flip on trackpast
  2. Stop on trackpast
  3. Do nothing on trackpast (i.e. continue tracking indefinitely)
I know Dan is always busy but this has been known about for a year now. The more 'bent knee' piers Lucas sells to accompany the e200 the more people will be flagging this up.

Please Don, could you have chat with Dan so that we can get this resolved. It really has become excruciatingly frustrating.

Many thanks & regards
Martin


SIMON
 

Don,

What Martin says makes sense and gets my vote :-)
 
However - regardless of how the params are set, a 'Do Gem FLIP' should do just that, simply moving the mount 10-15 degrees and stopping is not what anyone would expect from this button and I can't believe this is how any user would expect the button to function. So it feels to me like this is a bug that needs logging and fixing, I really don't want to send the mount back under warrantee, because physically it is simply awesome, and I waited 6 months for it and sold a lung to buy it, but it is being let down badly by bugs in the driver that make the mount very frustrating to use, 

We are all astronomers, it's a close knit community, I want the Sitech and Mesu partnership to flourish as much as Mesu and Sitech do, I want to shout on the roof tops at how good it is but to do that the bugs need to be fixed - I currently feel like a lemon for investing in something that doesn't work.

I appreciate it might take some time to build and test, can you please pass this on to Dan for his attention and can we please have a commitment to fix these genuine bugs. I appreciate the stresses software development brings - having managed large teams of software developers - but I also know that if the foundations aren't right you are just storing up trouble for the future - so the sooner these are fixed the better for everyone regardless of the mounts they use.

Sorry if this sounds like a rant, it's not intended that way, I'm genuinely trying to express the feelings I'm going through using the sitech controller - I hope I haven't upset anyone.

Many Thanks
Simon.  


Don W
 

Hi Simon and Martin,
I have great news for you.  095U version has new settings for the meridian limits and track past limits.  I have tried these limits on my SiTech mount and they work.  Also I found that the problems with commanding a meridian flip by Simon are NOT a bug but are pure operator error.

Here is the story:

The release 095U now allows the settings for meridian flip west PLUS track past limit to equal any value below 90.001°.  Yes you can set it to 90° if the west meridian limit is zero.  The setting of the east meridian limit does not affect the track past since you can only track west.  This should completely answer Martin's quest from a long time ago.

Now to Simon's question about commanding meridian flips.  SiTech will always do a flip when commanded (Features/do flip) IF the mount is not in the set meridian limits.  Simon set his limits to 45° west and -45° east.  So SiTech will NOT do a meridian flip (commanded or otherwise) in that 90 degree part of the sky because Simon told it so.  If you want to always flip on command, you have to set the meridian limits to zero.  It is as simple as that.

I talked to Dan Gray today and he told me about the latest change in 095U.  Actually the latest version is 095X at http://siderealtechnology.com/SiTechSetup095X.exe

I did not realize the change he made in 095U until today's phone conversation.  BTW, Dan is up to his ears in work for professional observatories (They are paying him), so we likely won't see any other changes in SiTechexe for a while.

Don W


MartinC
 

Hi Don,

 

Thanks for the info, I’ve just been trying 95U & 95X.

 

Although X comes after U it seems that the limit has been put back from 90 to 20 in X which seems a bit odd?

 

Yes you are correct. In U you can set the track-past to 90 but unfortunately the mirror slew bug is back in the North-East sky quadrant between the Northern Meridian & the 90 deg track-past limit. So if your target is in this quadrant & you plate solve, the mount shoots off to a point on the mirror opposite side of the Northern Meridian.

 

As before, you can quickly test this without needing to be connected to the mount. Just open Skyview in faking servos mode, slew to a point in the NE, then slew to the same point (or very close to it if there’s a star within a few arc seconds of it).

 

It’s a shame but I don’t think this one’s going to go away until Dan can look at a introducing a 3rd track-past option as previously requested. I think it’s the best solution for us ‘bent-knee’ pier users, plus the safety feature of the limit would still be available for those who do need it.

 

Best regards

Martin

 

 

 

 


SIMON
 

I'll have a look at the new version - it will be a couple of days.
I think you are saying...
o  track past + west limit < 90
o set west limit=0 to get correct behaviour for goto

I.e.
track past = 90
West limit = 0

I think if the "do GEM flip" isn't going to function in some configurations it should produce an error and not just move a little bit and stop. Also it seems it is only a problem if the mount moves in the wrong direction, if it moves correctly I can't see how it would hit any limits, and this is exactly what the mount does, it initially moves in the wrong direction before stopping.

No GEM mount I have ever owned would move this way as it would crash, the whole point is to keep the weights down during a flip.

Hopefully, I can update you on a couple of days.

Kind regards,
Simon

Sent via BT Email App



From: MartinC via groups.io <mncrane@...>
Sent: 6 January 2022 02:37:07 GMT
To: Sitechservo@groups.io
Subject: Re: [Sitechservo] Manual Meridian Flip not working #mesu

Hi Don,

 

Thanks for the info, I’ve just been trying 95U & 95X.

 

Although X comes after U it seems that the limit has been put back from 90 to 20 in X which seems a bit odd?

 

Yes you are correct. In U you can set the track-past to 90 but unfortunately the mirror slew bug is back in the North-East sky quadrant between the Northern Meridian & the 90 deg track-past limit. So if your target is in this quadrant & you plate solve, the mount shoots off to a point on the mirror opposite side of the Northern Meridian.

 

As before, you can quickly test this without needing to be connected to the mount. Just open Skyview in faking servos mode, slew to a point in the NE, then slew to the same point (or very close to it if there’s a star within a few arc seconds of it).

 

It’s a shame but I don’t think this one’s going to go away until Dan can look at a introducing a 3rd track-past option as previously requested. I think it’s the best solution for us ‘bent-knee’ pier users, plus the safety feature of the limit would still be available for those who do need it.

 

Best regards

Martin

 

 

 

 


Don W
 

Hi Simon and Martin and all,

OK, we have a problem with versions 095U and 095X.  I alerted Dan to this situation but I don't know when he can fix it.

095U allows track past + meridian Limit west to be set up to 90° but has the false meridian flip problem Under the Pole looking east.

095X fixes the under pole false meridian flip, but limits track past to 25°.

So choose which version is best for you until Dan can fix it all.

Don W


SIMON
 

Don,
I'm going nuts. I just cant get the mount to slew to objects in the east without pointing the weights in the air - I've changed the config to...

over pole                                                           under pole
00:00:00                Meridian Limit West            00:00:00
00:00:00                Meridian Limit East             00:00:00
25:00:00 Track Past Meridian Overlap

If I slew to the Moon currently in the East it always slews to the Moon with the weights up 
If I slew to Jupiter - currently in the south - it slews to Jupiter weights down
I've cleared the calibration data but just can't get the mount to behave correctly - also If I then do a meridian flip the mount only moves 180 degrees in RA and doesn't flip the scopes dec axis so it ends up pointing in the wrong direction.

But when I then tried a slew to M45 - close to the Moon in the East it pointed the telescope to the floor and I had to do an emergency stop before the Camera hit the pier. You can see that my config has an altitude limit of 0 degrees and also has 'keep above horizon' selected.




Any Advice appreciated.


 


Don W
 

Hi Simon,

The angles you set for meridian limits are measured from the zenith.  So your setting zero for Under Pole is plain wrong, you should set it to 180 or 178 east or -180/-178 west.

These might be causing your funny mount actions.

Don W


MartinC
 

Hi Simon,

Given that track-past issue for us bent-knee pier users is yet to be resolved I have simply opted to stick with pre-ordained, mid sequence meridian flips. Really frustrating but I've found it to be the easiest temporary solution.

So here are my settings if it's of any help. In my sequencing software I arrange for the flip to take place in between the meridian limit & the track-past limit. I do not experience the issue that you describe.

By the way Don,

I've never understood your comments about meridian limits being measured from the zenith? In Skyview all the grid lines eminate from the NCP? Just curious about your decription.

Hope this helps Simon.

Best regards
Martin


SIMON
 

thanks I'll try this


SIMON
 

Thanks - I knew this was working before I changed the settings - it's behaving itself now. :-)


Don W
 

Hi Martin and all,

OK, let me explain meridian limit angles.  I say they are based on the angle from zenith.  That is to say they are like RA regardless of DEC.  The line between the two Earth Poles is a dividing line between above pole and below pole.  So the meridian above pole runs across the sky and through the zenith as a half circle around Earth.  So if you set the above pole limit to zero, that half circle is the limit for meridian flips when the limit is set to zero.

Now the Under Pole meridian limits are based on the half circle Opposite the above pole.  So it is the half circle on the "other side of Earth" and passes through the opposite of the zenith.  So that line is 180° from the visible meridian.  This includes the "under pole".  So reference to under pole angles is.near 180°.

Now is that clearer than mud?

Don W


MartinC
 

Hi Simon, 
Glad to hear that.

Best wishes
Martin


MartinC
 

Hi Don,

Well if I was thinking about an Alt\Az grid then I'd agree, but for an Equatorial grid then the common point between my genuine local meridian, Sitech's meridian limit lines & the track-past line is the NCP. Once moved from zero those lines do not pass through the zenith.

Best regards
Martin


Don W
 

Hi Martin,

True, the limit lines (other than zero) do not pass the zenith.  But the zenith is the zero Reference for all the meridian limits.

Don W


SIMON
 

I think a diagram might be needed!

Sent via BT Email App


SIMON
 

I'm set-up exactly the same as Martin in his earlier post on this topic, and the mount is acting properly during goto's, however the manual GEM flip still doesn't perform correctly - but just to be sure - my expectation is a GEM flip should rotate the RA axis and the DEC axis so that it is back pointing at the target it was on just prior to the flip but the scope will now the opposite side of the pier to where it was - but this doesn't happen the DEC axis doesn't seem to move at all during a flip.

My scenario is this:
I have a 6hr observation run on an exo-planet transit, it starts in the east and ends in the west.
I slew to the target, weights are down - as expected - but because this is going to pass through the meridian I want to start with the weights up, this way the mount will in in the correct orientation for the rest of the observation and no meridian flip will be necessary when the scope passes through the meridian - i.e. in the middle of the observation.

however because the GEM flip doesn't bring the scope back to pointing where it was prior to the flip I can't do this - I don't mean the scope is slightly out is is pointing in completely the wrong direction - basically it is only moving the RA axis 180 degrees so appears to only be doing half of what is necessary to perform a flip correctly.

Am I missing something?


MartinC
 

Hi Simon,

Assuming by manual flip you mean using the "Do GEM Flip" button? I've never used it but out of curiosity I've just tried it. I'm using 95U software. I can flip the mount backwards & forwards manually from any position at will without a problem. My dec axis rotates as you'd expect as the mount travels through the pole.

So I'm not sure why you cannot do the same - maybe a setting related to the DEC elsewhere? Obviously you need to know the reason but I was thinking that for your speciffic exo-planet observations maybe try using EQ mode. It might be better in this case?



Initialise with the scope 'Looking West' & then do a goto to your target in the East. The mount should just slew, crossing the meridian without going through or over the pole & place the wieghts up. Then just track as normal east to west  recrossing the meridian & into a wieghts down position. Try it & see what you find\think.

Best regards
Martin