Date   

Re: Our Ice Storm and Power Outage

Joshua Hufford
 

That is some serious ice!

Stay safe, glad you have power back now. 

Josh

On Wed, Feb 17, 2021 at 10:36 AM Dan Gray <grayarea@...> wrote:
Hi all,
Sorry I've been missing in action.  We lost power Friday night, and finally got power back last night.
We've been living in Samantha's RV.  Now that we have I-Net again, I'lll get caught up on emails.

Here's a video of our Ice Storm.

Dan


Re: Mesu 200 Mk2 Tracking stops close to equator

Jose Ignacio Sanchez Rodriguez
 

Hello Paul,

Yes, I will first run the GA with the Mesu and only then try it with the CEM 60 on the same area of the sky.

The more I think about the guiding behaviour and the RA reading behaviour I saw in the video, the more I lean towards the idea of the problem being either balance or the RA servo not working well.
I´ll just toss my reasoning here. Please let me know if it is wrong.

What I see is that the RA reading on SiTech.exe is decreasing. As I understand this, RA increases EASTward, so the mount´s driver is telling me that the mount is actually moving WESTward faster than sidereal. This cannot be due to the guiding commands cause they are EASTward. So it has to be either the setup being scope heavy (I am west of the pier) or the RA servo not working well. That would also explain why the mount does not respond to the guide commands. 

Best Regards,

Jose


Re: Mesu 200 Mk2 Tracking stops close to equator

Roland
 

Torben,

Sorry to hear that you’re having so many problems.  

If you are getting constant drift in one direction then there are not many possible causes. Namely:
  • Poor polar alignment.
  • Wrong tracking rate.
  • Significant imbalance of the mount which may be causing some slippage.  This would not normally be an issue with a worm/crown gear mount but, as far as I can understand, the Mesu mount has some sort of clutch for the direct drive.

If you are getting jumps superimposed over the drift, then I can only see the following possible causes:
  • Mechanical problems with the mount.
  • Guiding overshoot (if you’re guiding).
  • Guiding which is trying to follow the seeing because guide exposures are too short.
  • External factors such as wind.

I don’t know if you have done this yet but I suggest you try to graph your drift without applying any guiding corrections at all.  Do not use a mount model.  In Maxim, you simply set the mount to guide, set aggressiveness to zero and do a tracking graph over several worm cycles.  This means you will get the periodic error superimposed on the drift and quick jumps but you should essentially see a line which goes in one direction with respect to time.  With SiTech you can adjust the tracking rate based on the following note from Dan (which I posted a few days ago):

"If it ALWAYS drifts the same amount for anywhere in the sky, I would check my ticks per rev, also use a time server, and software that keeps updating your clock.

You can manually edit your SiTech.cfg file (make sure you're not running SiTechExe when you edit the file).

Look for the variable labeled "RightAscensionRate=0"
Change the zero to whatever you want.
This is in arc seconds per second, can be negative.
Dan”

This is a little laborious because you need to close SiTech each time, alter the config file and start SiTech again but you can get the hang of it fairly quickly.  If you can tame the drift then you will be left with the jumps and the PE.  The PE you can correct by guiding but the jumps are potentially a major hurdle if they’re due to mechanical issues.  Correcting fast jumps is very hard.  About the only thing you can do is to use an adaptive optics setup but this means extra costs and messing around and to correct quickly (say, at a few Hz) you need quite bright stars.

Hope this helps.

Roland.



On 17 Feb 2021, at 16:44, T. van Hees <torben@...> wrote:

Hello again. I am grateful for all the assistance I got in this community, so here is my most recent data. In the link you can find two of my recent guiding logs. Many of the log parts are with dithering because I just let Voyager run for the rest off the night, as I could not get the drift under control. I just took very short exposures with the RASA so got some data nevertheless. There is one run of Guiding Assistant, also attached as a screenshot. Within the logs, there is one run where DEC stops responding to guider commands: This is due to me not correctly tightening a clutch, not a mount error.

You will find RA drift between 2.5" and 14"/minute as well as some 20-30s spikes. I have tested again with a lighter and proven setup (my RC8 with OAG). I have currently no access to the log but I can describe the results: The 30s-spikes are far smaller, barely detectable (0.2" instead of 1"), but the RA drift was the same. DEC always seems to correct fine with both setups. That same setup works without problems on a Heq-5, so I think I can safely ignore a flex error. I realise longer logs might be beneficial to diagnose what exactly is wrong with the mount, but I can not present those. I have no more interest to tackle this problem and am in the process of contracting a Dutch lawyer to try and settle the whole mess for me and cut my losses. Dealing with Mr Mesu has been tedious and exhausting. I want nothing more to do with him and his business. I feel sorry that more people than just me are affected.

Links to logs:
https://www.icloud.com/iclouddrive/0_WQwxyB10KaGZzi4k3u6WY1g#Mesu
<Drift4.PNG><Drift3.PNG><Drift2.PNG><Drift.PNG>


Re: Mesu e200 bent knee pier - GEM vs EQ

Dan Gray
 

Hi Jonk,
Here's an image with settings.  Look carefully on the right side, you'll see the meridian flip lines.
In the upper left is the settings:


On Wed, Feb 17, 2021 at 7:31 AM Don W <westergren@...> wrote:
Hi Jonk,

A GEM is not a FORK/Equatorial.  It really is best to use a GEM as a GEM.

Set the Meridian West to 90° and leave the Meridian East at zero.  That will make all motion looking east with counter weight Down, and all looking west counter weight Up.  The mount will never do a meridian flip.

Set your altitude limit to whatever you want, either with the fixed alt limit in Mount Parms or using the SiTech.hrz file.  Generally astrophotography is badly affected by refraction below 30° altitude.  However you can move below the altitude limit with the handpad to set a lower Park position if desired.

DEC motion is either North (toward the North Pole) or South toward the South Pole.  If you move toward a Pole from above, when you get to the pole, the DEC motion reverses when pointed BELOW the pole.  This is true regardless of a GEM or EQUATORIAL.  Parking at the pole is truly ambiguous and will cause you problems.  Parking at the pole can not initialize RA.

The reversal of Dec you experienced when set as EQ is exactly why I say don't set it as EQ.

Don W


Re: Fw: Coord issue? Video attached via dropbox

Dan Gray
 

Sounds like the guider was keeping it centered, and either there's a setting wrong in the SiTech.cfg file, or polar alignment/slippage.
Here's what to look for in the SiTech.cfg file.
Make sure you edit the SiTech.cfg file when SiTechExe is not running
Also motor ticks per rev could be wrong,
Balance and roller pressure are critical.

RightAscensionRate
DeclinationRate
They should both be zero.
The reason I mention this possibility, is this got changed somehow in someones config file.

Dan



On Thu, Feb 11, 2021 at 10:12 AM jaspal <jaspaltheknight@...> wrote:



From: Jaspal Chadha <jaspaltheknight@...>
Sent: 11 February 2021 16:29
To: Sitechservo@groups.io <Sitechservo@groups.io>
Subject: Coord issue?
 

Hi all,
                Can I please pick your brains? so as you are aware I have been having issues with my Mesu Mark 2 mount  drifting every second in RA making it unusable or guidable at times. After in contact with Lucas Mesu and problem solving I changed to a new computer, rebalance and cable management, it's early days to say 'WHOOP WHOOP problem solved' but yesterday it went fine for the hour and half i had ( only tested in the WEST )

I use Voyager software that controls everything and all the drivers are up to date

I start voyager, mount is pointing WEST

Sitech showed the mount as tracking.... 'I completed a Plate Solve Actual Coord' and the Sitech box appeared and press INIT to confirm ( making sure the bottom bit showing WEST) and then press SYNC in voyager and the RA and DEC readings are the same... 

Voyagers allows you to search for target and uses ALADIN to show what image looks like in your pre-defined FOV setup, You can also free search around sky screen and do a precise Goto which will plate solve the target.   

Last night I choose target NGC457 and it slewed in bang onto to my FOV I then began PHD2 guiding and was at around TOT 0.50. 

After consistent frames  perfectly centred  I pressed the 'Get telescope position' It showed that the scope had moved considerably away from the target, however each frame it was still bang in the middle of the FOV and guiding graph good.

see images below ( first image shows R.A 01:18:11:8 and DEC 58:23:41 in SITECH ) and the in Voyager RA 01:18:12 DEC 58:23:41)




Second image shows actual telescope position within 30 mins or so of imaging




Third image shows the actual sub frames coming out which is dead centre and not repsentative of image 2 (above)  




The developer of Voyager states, usually mount work in JNow or you have done a wrong sync or not right epoch seems & can't help further 

Could this possible be causing RA drift, something clashing? 

Thanks in advance 


Re: Mesu 200 Mk2 Tracking stops close to equator

T. van Hees
 

Oh, it seems one has to register to be able to download those logs. Did not know that. 


Our Ice Storm and Power Outage

Dan Gray
 

Hi all,
Sorry I've been missing in action.  We lost power Friday night, and finally got power back last night.
We've been living in Samantha's RV.  Now that we have I-Net again, I'lll get caught up on emails.

Here's a video of our Ice Storm.

Dan


Re: Mesu 200 Mk2 Tracking stops close to equator

T. van Hees
 

Hello again. I am grateful for all the assistance I got in this community, so here is my most recent data. In the link you can find two of my recent guiding logs. Many of the log parts are with dithering because I just let Voyager run for the rest off the night, as I could not get the drift under control. I just took very short exposures with the RASA so got some data nevertheless. There is one run of Guiding Assistant, also attached as a screenshot. Within the logs, there is one run where DEC stops responding to guider commands: This is due to me not correctly tightening a clutch, not a mount error.

You will find RA drift between 2.5" and 14"/minute as well as some 20-30s spikes. I have tested again with a lighter and proven setup (my RC8 with OAG). I have currently no access to the log but I can describe the results: The 30s-spikes are far smaller, barely detectable (0.2" instead of 1"), but the RA drift was the same. DEC always seems to correct fine with both setups. That same setup works without problems on a Heq-5, so I think I can safely ignore a flex error. I realise longer logs might be beneficial to diagnose what exactly is wrong with the mount, but I can not present those. I have no more interest to tackle this problem and am in the process of contracting a Dutch lawyer to try and settle the whole mess for me and cut my losses. Dealing with Mr Mesu has been tedious and exhausting. I want nothing more to do with him and his business. I feel sorry that more people than just me are affected.

Links to logs:
https://www.icloud.com/iclouddrive/0_WQwxyB10KaGZzi4k3u6WY1g#Mesu


Re: Mesu mark 2 RA drift update

Don W
 

Hi Jonk and all,

Balance in DEC must be done in two orientations:  Horizontal scope and vertical scope.  This is especially true when there is ANY non-symmetrical installation of scopes or multiple scopes, guide scopes, or cameras.  It is true that balance in Dec should be done before balancing RA.

Don W


Re: Mesu mark 2 RA drift update

gary neilson
 

Hi All,

Its concerning to read all of these RA problems with the Mesu Mk2. I have the mount (received October last year.) and haven't had any of the issues fortunately.

It makes me wonder if the new clutch system of the Mk2 is part of the issue? As motor spacing is critical, I always make sure the lever is pressed firmly to lock the motor in place. Similarly for the axis clutches as any additional friction would mess things up. 

Other steps I've taken include:

  • Acceleration. Reducing the acceleration parameter in servo config by half which is probably very conservative. This prevents possible slip at the beginning or end of a slew.
  • Balance. Ensuring its balanced in RA/DEC off the mount. I address any off-axis loads that would exceed the torque spec of 10NM (even though it appears balanced when the CW bar is vertical or horizontal). As an added check I've found if I run guiding assistant in PHD2 and I see any backlash, its likely some minor slippage is occurring - I tend to ignore this if its small and do not compensate for it in PHD2 settings. Repeating the calibration and measurement in a different part of the sky clears it so certain angles do have an impact it appears. 
I used to use the dowel method described by Jonk. But now use an old Wii balance board (luckily its survived our  last move!) and software I found for a project at the University of Colorado. Its much safer as I simply place the scope/accessories on the board and adjust until the COG is centred in the reticle! No more wobbling of heavy equipment while finding the fulcrum!

Cheers

Gary.


Re: Mesu e200 bent knee pier - GEM vs EQ

Don W
 

Hi Jonk,

A GEM is not a FORK/Equatorial.  It really is best to use a GEM as a GEM.

Set the Meridian West to 90° and leave the Meridian East at zero.  That will make all motion looking east with counter weight Down, and all looking west counter weight Up.  The mount will never do a meridian flip.

Set your altitude limit to whatever you want, either with the fixed alt limit in Mount Parms or using the SiTech.hrz file.  Generally astrophotography is badly affected by refraction below 30° altitude.  However you can move below the altitude limit with the handpad to set a lower Park position if desired.

DEC motion is either North (toward the North Pole) or South toward the South Pole.  If you move toward a Pole from above, when you get to the pole, the DEC motion reverses when pointed BELOW the pole.  This is true regardless of a GEM or EQUATORIAL.  Parking at the pole is truly ambiguous and will cause you problems.  Parking at the pole can not initialize RA.

The reversal of Dec you experienced when set as EQ is exactly why I say don't set it as EQ.

Don W


Re: Mesu 200 Mk2 Tracking stops close to equator

paul K
 

I think you're right Jose, the same rig on a different mount isolates the one variable we're interested in; you'll prove the performance of the kit and that will just leave the mount. I think this exercise will produce valuable evidence.

As you identified, perform the trial in the same area of sky where you had the problem.

It might be worth doing the guiding assitant trial before switching to the other mount, just so you're testing the current context before making any change. Then change to the other mount and repeat.

Good luck,
Paul


Re: Mesu 200 Mk2 Tracking stops close to equator

Jose Ignacio Sanchez Rodriguez
 

Thanks for your answer Paul,
I am actually using an OAG. That’s another point that makes me almost rule out differential flexure as a possible explanation. 

About using the main camera as a guider, that would clearly help to rule out (or in) the possibility of differential flexure between the imaging and guiding cameras. Even if this possibility is small when using an OAG. But it is worth a try.

I will also perform the test with the same rig both on the Mesu and the CEM60. I think that this could be the acid test here. If the same rig works on one but not on the other, the conclusion is clear. Except for balance, but that is really a long shot with the MKII.

I’ll post my results when I have the chance to setup outside again.

Thanks again. Best Regards,

Jose

Enviado desde mi iPhone

El 17 feb 2021, a las 12:12, paul K <paulskirk53@...> escribió:

Interesting analysis fom the PHD2 forum Jose. I can't speak directly to the MESU mk II because I don't have one. With my MESU mk I, I know it is out of balance, simply because it is almost impossible to balance it effectively due to the motors being constantly engaged on that model. It tracks and guides just fine, with guiding corrections in E and W . Given the clutches arrangement on the MESU mk II, it will be a doddle to balance, just use the process in the Starizona link for balance across the range of movement - that did catch me out a few years back when my mount was significantly out of balance, it tracked for a while then stopped, rebalance then it was fine.

Re flexure, differential flexure is a significant problem if it's present. I also had this when trying to guide with a separate guidescope which wasn't fixed absolutely rigidly to the main scope. Subsequently I had this again when trying to guide a C11 sct with an external guide scope, which I susbsequently found out is not possible, you have to use OAG to guide SCTs because of the movement of the primary mirror as the scope tracks. (there is a body of evidence for this assertion). So one good way to remove the potential influence of differential flexure between the main scope and the guide scope is to temporarily move to an OAG setup if you can. Just thinking out loud here 'cos i've never tried it, but what about using your main imaging camera as the guide camera for PHD2? This would be a no cost solution. You could use the PHD2 viewer to select a star, let it track and guide and then inspect the log.

Also, going back to Yann-Eric's idea of using PHD2's guiding assistant, the PHD2 helpfile on this utility states that you need to use your imaging camera (not the guide camera) for that process anyway.

I think you're  getting to an interesting point with things now - good luck.
Paul


Re: Mesu mark 2 RA drift update

Jonk
 

I agree about balance - you need to balance DEC in all possible directions first, otherwise RA will not be in balance in certain parts of the sky you're pointing at.

An easy way to do this is place your entire imaging rig on a metal rod, or broomstick on a bench. You should be able to find the centre point of your rig by moving the whole thing 360 degrees around the rod / broom handle.

Move scopes back and forth and add weights if necessary (especially if you have L-R balance and cannot move the scope L-R).

One you've found balance in all possible directions, reinstall onto the mount with the centre of balance in the centre of the DEC and it should be fine.

Then you can set the RA balance. This may help with reducing slippage.


Re: Mesu 200 Mk2 Tracking stops close to equator

Jonk
 

One thing I see that I would do differently, is change your guide camera exposure to something longer than 2 seconds, but without saturating the stars.
Have you tried multistar guiding? This probably won't necessarily fix it but may help reduce the effects of seeing.
I routinely use at least 4 seconds on my guiding, I've seen some use up to 10 seconds.


Re: Mesu mark 2 RA drift update

Roland
 

Guys,

For what it’s waorth, apart from my own systems which use SiTech, I know of at least one other system that uses SiTech on a smaller Bellincioni mount which performs flawlessly.

There is always a bit of setting up to do but, since I use a separate observatory control system, once this is done SiTech becomes absolutely transparent. Last year during the peak of COVID, I worked for 6 months remotely without a hitch. 

I can’t make a comment about the Mesu mounts but I think you can rest easy with the accuracy and reliability of the SiTech system. 

Roland. 

On 17 Feb 2021, at 10:50, Jose Ignacio Sanchez Rodriguez <jsanchez.es@...> wrote:

Hello Torben,

As others have said there is no reason to apologise. I think this is the right place to air these sort of concerns. In my case your thread has helped me a lot when thinking about my issue.

One thing that I am not sure if you tried, maybe you have, is to use the same rig on a different mount. If the discussion is wether the problem is on the mount or on the imaging rig, if you can make the same rig work on a different mount then the discussion should be almost settled. The only lingering issue would be on balance, as a friction drive mount can slip if not properly balanced. But that should be easy to settle by recording the mount balancing exercise. 

Best Regards,

Jose


Re: Mesu 200 Mk2 Tracking stops close to equator

paul K
 

Interesting analysis fom the PHD2 forum Jose. I can't speak directly to the MESU mk II because I don't have one. With my MESU mk I, I know it is out of balance, simply because it is almost impossible to balance it effectively due to the motors being constantly engaged on that model. It tracks and guides just fine, with guiding corrections in E and W . Given the clutches arrangement on the MESU mk II, it will be a doddle to balance, just use the process in the Starizona link for balance across the range of movement - that did catch me out a few years back when my mount was significantly out of balance, it tracked for a while then stopped, rebalance then it was fine.

Re flexure, differential flexure is a significant problem if it's present. I also had this when trying to guide with a separate guidescope which wasn't fixed absolutely rigidly to the main scope. Subsequently I had this again when trying to guide a C11 sct with an external guide scope, which I susbsequently found out is not possible, you have to use OAG to guide SCTs because of the movement of the primary mirror as the scope tracks. (there is a body of evidence for this assertion). So one good way to remove the potential influence of differential flexure between the main scope and the guide scope is to temporarily move to an OAG setup if you can. Just thinking out loud here 'cos i've never tried it, but what about using your main imaging camera as the guide camera for PHD2? This would be a no cost solution. You could use the PHD2 viewer to select a star, let it track and guide and then inspect the log.

Also, going back to Yann-Eric's idea of using PHD2's guiding assistant, the PHD2 helpfile on this utility states that you need to use your imaging camera (not the guide camera) for that process anyway.

I think you're  getting to an interesting point with things now - good luck.
Paul


Mesu e200 bent knee pier - GEM vs EQ

Jonk
 

I have a Mesu e200 which is destined for installation on a custom bent knee / flipless pier. I wanted this to avoid meridian flips and also to eliminate the possibilty of any crashes.

In the Sitech settings as we know, there are choices for how you wish to use it. The Mesu e200 comes set as default to GEM, with meridian limits set.

I have played with these limits and it would seem as though the only way to completely remove all limits (which is what I want), is to set it as an EQ mount.

I played with EQ mode last night on the bench, and I have a question. I'm using the latest Sitechexe 95H and the controller is as far as I know, contains the latest firmware.

In GEM mode, starting in the typical park position (DEC at 90 degrees, weights down, facing NCP), clicking on a star due E or W (so DEC at 0 degrees), syncing, pushing N towards NCP and setting park all works as expected. The mount is now initialised and parked. Removing power, closing sitech then starting it all back up again works as expected, no need to reinitialise, gotos work etc.

So, changing onto EQ mode, this removes all meridian limits etc. Good. Repeat the procedure - weights down, DEC at 90 degrees, click on a star due E or W (so DEC at 0 degrees), sync. All good so far. Pressing N (software or hand controller) to move back to the park position, the DEC moves the opposite direction. Gotos do the same, so does park (after setting park in the correct place). I'm not sure I understand this, as skyview shows the reticle behaving correctly, i.e it moves DEC N towards the NCP whereas the mount DEC moves in the opposite direction.
 
My question - is it just a case ot setting the 'reverse DEC servo / encoder' in the servo setup or is there something else I'm missing?

I am certain that I want to remove all GEM limits, not just extend them to max, I don't have any possibility of the mount crashing the scopes into anything.

Here's a render of my pier and Mesu. You can see that a crash is not possible.

2003782277_Mountonpierwithweightsrender2.jpg.264c5d37b74969c953dd1cfa1ce039ae.jpg


Re: Mesu mark 2 RA drift update

Jose Ignacio Sanchez Rodriguez
 

Hello Torben,

As others have said there is no reason to apologise. I think this is the right place to air these sort of concerns. In my case your thread has helped me a lot when thinking about my issue.

One thing that I am not sure if you tried, maybe you have, is to use the same rig on a different mount. If the discussion is wether the problem is on the mount or on the imaging rig, if you can make the same rig work on a different mount then the discussion should be almost settled. The only lingering issue would be on balance, as a friction drive mount can slip if not properly balanced. But that should be easy to settle by recording the mount balancing exercise. 

Best Regards,

Jose


Re: Mesu 200 Mk2 Tracking stops close to equator

Jose Ignacio Sanchez Rodriguez
 
Edited

Hello,

I got an answer at the PHD2 forum (phd2 forum answer). Basically it seems that the guider constantly correcting to the east while the telescope is on the west of the pier (pointing east) rules out cable snag, static resistance or a loose clutch. It is not that something is preventing the mount form tracking west, but rather that the mount is tracking a little too fast westward. The possible explanations have to do with focuser sag or flexure. As if the guide camera is falling west. They mention that the previous explanation assumes the mount is tracking at constant sidereal rate, which takes me back to square one, only this time I have more elements to judge the situation.

I cannot be 100% sure, but I am pretty sure, that the rig has no flexure nor focuser sag. What reinforces me on this is that using the same rig I was able to guide successfully since mid October up until the end of January. Even after changing the focuser for a more rigid one, the Nitecrawler, the problem persists. I also tried this same setup with a CEM60 mount and had a much better guiding experience. There is no divergence of the RA guiding error from the start. Corrections are both east and west. The PA error is much smaller but the rate of drift I had on the MESU (6.63 arcsec/min) should be easily guidable with 2 sec exposures I was using (it is 0.22 arcsec per exposure). Unfortunately, although it was on the same object, I performed the CEM 60 test from 18:30 to 19:10, so not exactly the same scope position. 

At this point I think the most likely explanations are either a balance problem or a tracking problem.
The MESU, being friction drive, is more sensible to balance issues than the CEM 60, being a worm drive system. There is a possibility of slippage. So that could explain the difference in performance, given the same rig, from one mount to the other. I honestly doubt that there is a balance issue. The MESU MKII is very easy to balance.
I hope that running the guide assistant on my next session will help a lot to either confirm or rule out a tracking issue.

I have scheduled a skype call with Lucas Mesu on Friday during which we will try to rule out any mechanical issue.

I´ll keep you posted.

Thanks again,

Jose

p.s: Since I started having the guiding issues my PA error has been also bigger. Before I used to have sub arcmin PA error, now I have 5-6 arcmin error. It is clear to me that if PA error is calculated via PHD2 measured drift then, until. solve the drift issue I won´t be able to know wether that error is real or not. Kind if a Catch-22 situation.

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