Mach 1 tracking problem


Bruce Donzanti
 

Over the past 2 nights I am getting very bad trailing stars.  I've checked all of the usual possible problems: balance, cables, and PA all seem fine.  Clutches are tight and all connections tight.  I tried two cameras to ensure that was not the problem.  I am out of ideas.  My C11" is on the Mach 1 on a steel pier well above ground and has been working fine.  Stacking will occur but getting elongated stars.  Other suggestions?


Ray Gralak
 

Maybe you have accidentally set the mount to track at the solar or lunar tracking rate?

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Tuesday, May 7, 2019 9:14 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Mach 1 tracking problem



Over the past 2 nights I am getting very bad trailing stars. I've checked all of the usual possible problems: balance,
cables, and PA all seem fine. Clutches are tight and all connections tight. I tried two cameras to ensure that was
not the problem. I am out of ideas. My C11" is on the Mach 1 on a steel pier well above ground and has been
working fine. Stacking will occur but getting elongated stars. Other suggestions?


Roland Christen
 


Over the past 2 nights I am getting very bad trailing stars.
Are you guiding? If so, what is your guider graph telling you?

Rolando


-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Tue, May 7, 2019 11:14 pm
Subject: [ap-gto] Mach 1 tracking problem



Over the past 2 nights I am getting very bad trailing stars.  I've checked all of the usual possible problems: balance, cables, and PA all seem fine.  Clutches are tight and all connections tight.  I tried two cameras to ensure that was not the problem.  I am out of ideas.  My C11" is on the Mach 1 on a steel pier well above ground and has been working fine.  Stacking will occur but getting elongated stars.  Other suggestions?



Bruce Donzanti
 

No guiding.  Never need to.  Only doing short exposures- like 30-60 sec stacks

I emailed George several emails with pics of the images and my setup hoping that would help. Very strange that this all of a sudden just started happening.  Scope is up over 12 ft on a pier and nothing was changed.

On Wed, May 8, 2019 at 11:35 AM chris1011@... [ap-gto] <ap-gto@...> wrote:
 


Over the past 2 nights I am getting very bad trailing stars.
Are you guiding? If so, what is your guider graph telling you?

Rolando


-----Original Message-----
From: donzantib@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Tue, May 7, 2019 11:14 pm
Subject: [ap-gto] Mach 1 tracking problem



Over the past 2 nights I am getting very bad trailing stars.  I've checked all of the usual possible problems: balance, cables, and PA all seem fine.  Clutches are tight and all connections tight.  I tried two cameras to ensure that was not the problem.  I am out of ideas.  My C11" is on the Mach 1 on a steel pier well above ground and has been working fine.  Stacking will occur but getting elongated stars.  Other suggestions?



Roland Christen
 

A really good way to figure out whether the mount is tracking is to do an analysis of several worm periods to see whether PE correction is working or not. Pempro is probably the most effective way to analyze a mount's performance. Offsetting the azimuth axis and taking an image of RA trailing over a period of 15 - 20 minutes is another. There are other ways too (Google can help).

Best way is to be your own investigator and then post the results. Just saying that you have trailing stars gives zero clue as to where the problem may be.

Rolando



-----Original Message-----
From: Bruce Donzanti donza2735@... [ap-gto]
To: ap-gto
Sent: Wed, May 8, 2019 10:54 am
Subject: Re: [ap-gto] Mach 1 tracking problem



No guiding.  Never need to.  Only doing short exposures- like 30-60 sec stacks

I emailed George several emails with pics of the images and my setup hoping that would help. Very strange that this all of a sudden just started happening.  Scope is up over 12 ft on a pier and nothing was changed.

On Wed, May 8, 2019 at 11:35 AM chris1011@... [ap-gto] <ap-gto@...> wrote:
 

Over the past 2 nights I am getting very bad trailing stars.
Are you guiding? If so, what is your guider graph telling you?

Rolando


-----Original Message-----
From: donzantib@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Tue, May 7, 2019 11:14 pm
Subject: [ap-gto] Mach 1 tracking problem



Over the past 2 nights I am getting very bad trailing stars.  I've checked all of the usual possible problems: balance, cables, and PA all seem fine.  Clutches are tight and all connections tight.  I tried two cameras to ensure that was not the problem.  I am out of ideas.  My C11" is on the Mach 1 on a steel pier well above ground and has been working fine.  Stacking will occur but getting elongated stars.  Other suggestions?





Bruce Donzanti
 

Ran more captures tonight to observe trailing stars.  I checked PA once again and rebalanced scope and checked all connections and cables. 


The drift is in RA and it made no difference as to whether I had PEM enabled or disabled.    I observed the drift and could mimic it by a slight movement in RA with the controller (SkySafari in this case).  I assume that means I have a periodic error problem.  Would that be a valid assumption?  I was surprised that the PEM enabled vs. disabled made no difference which is why I still am not certain that that is the problem.

Is PemPro the only way to fix it?  I do not have it so would have to learn it.  


Stuart Heggie <stuart.j.heggie@...>
 

I'm sure I missed some earlier posts but this sounds like you have the wrong tracking rate set not PE. What tracking rate are you using? If you've picked lunar or solar then that for sure would cause problems. 


On Fri, 10 May 2019 at 22:44, donzantib@... [ap-gto] <ap-gto@...> wrote:
 

Ran more captures tonight to observe trailing stars.  I checked PA once again and rebalanced scope and checked all connections and cables. 



The drift is in RA and it made no difference as to whether I had PEM enabled or disabled.    I observed the drift and could mimic it by a slight movement in RA with the controller (SkySafari in this case).  I assume that means I have a periodic error problem.  Would that be a valid assumption?  I was surprised that the PEM enabled vs. disabled made no difference which is why I still am not certain that that is the problem.

Is PemPro the only way to fix it?  I do not have it so would have to learn it.  


Bruce Donzanti
 

Tracking is sidereal.  I checked it.  


Roland Christen
 

I hope you realize that Sky Safari does NOT turn on PEM. You are basically running without PE correction and thus are seeing the normal periodic error in Ra of about 5 arc sec.

You can see your PE by offsetting the azimuth axis about 10 degrees and letting the camera capture about 15 minutes of star trails. This is a very simple test that every amateur should know and can tell you immediately how much PE your mount has.

There are several programs that allow you to record and download a PE curve to your mount controller. PEMPro is the best of the bunch and is not hard to learn. You can try it free and I would encourage you to buy it if you will be doing unguided imaging with your setup.

Finally, with your scope and focal length you are well advised to set up a guider, otherwise you will always be fighting drift. There is no way the mount can compensate for other drift problems brought on by atmospheric refraction, differential flex etc etc. Do yourself a favor and stop messing around with unguided imaging. It just doesn't work that easily and takes a lot of knowledge to apply properly. It isn't worth it for most people.

Roland



-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Fri, May 10, 2019 9:44 pm
Subject: [ap-gto] Re: Mach 1 tracking problem



Ran more captures tonight to observe trailing stars.  I checked PA once again and rebalanced scope and checked all connections and cables. 


The drift is in RA and it made no difference as to whether I had PEM enabled or disabled.    I observed the drift and could mimic it by a slight movement in RA with the controller (SkySafari in this case).  I assume that means I have a periodic error problem.  Would that be a valid assumption?  I was surprised that the PEM enabled vs. disabled made no difference which is why I still am not certain that that is the problem.

Is PemPro the only way to fix it?  I do not have it so would have to learn it.  



Bruce Donzanti
 

No - I do not realize many things about astronomy which is why I am asking.  Hoping to get a response without an attitude.

I enabled PEM using the AP ASCOM driver through ScarpCap, not Skysafri.  If that means it is still off, then fine, it is off.  My mistake.  Just trying to get educated.  

I can use a guider and will try.  My point has been that this has never been required in the past.  I have had decent 30-60s stacked unguided exposures for a couple of years with this mount but not anymore. 

I will also teach myself PemPro.

Thank you.
 


Roland Christen
 

The periodic error of a mount changes thru use because the worm and worm wheels rub against each other and thus wear. It only takes a few molecules of metal being worn off the worm to change the periodic error curve by 1 - 2 arc seconds. With your focal length a 2 arc sec error results in trailed stars, that is just fundamental fact. It may not show up with a 400mm focal length refractor, but a C11 has almost 2800mm of focal length, so every error is multiplied by a factor of 7 compared to the short scopes most imagers use.

Why does a worm wheel wear in today's mounts and not so much in the old GEMs back in the film era? The main difference is that today we do a lot of high speed slewing to get from one object to the next. The old mounts never had this capability and the worms turned so slowly that it would take a century to get the same wear that we get today running at 1200x slew speeds in one year. In fact, in those old mounts we never even greased the worms because that would attract dirt and dust, being that most of them had open gears. In today's GoTo mounts it is important to re-grease the mounts at least once a year - we have grease kits available for our mounts (call the office). Good lubrication helps to prevent excessive wear on a GoTo mount.

If you want to eliminate PE, you will have to periodically monitor your mount's periodic error with a program like PEMPro or PHD2. You can try PEMPro for free for a period of time and see if you like it. It has other features that are quite nice to have and can be used with any other mount that you have. It will definitely show the extent of the PE of your worm gear and create a very accurate curve to cancel it out so you can get back to 60 second un-trailed images.

If your worm has a major problem, PEMPro is the way to record that and will give you proof that something needs to be fixed. Just showing a 5 minute trailed image shows absolutely nothing about the state of the worm and worm wheel, whereas PEMPro can definitely pinpoint whether there is a problem or not. In my experience a frequent user of a GoTo mount will need to re-do the PE curve or at least check it every observing season (once per year up north or once every 6 months down south). Usually that's all it takes to get the PE back to 1 arc sec or less.

Can you have a damaged gear? Yes, it's possible. In a few rare instances the gears were abused and had sections on them that were damaged due to improper meshing procedure. In those cases the images showed huge trails only at certain places in the sky (at certain worm wheel angles where the damage occurred). In other parts of the sky the mount worked fine (no damage at that part of the worm wheel). This doesn't appear to be the case in your mount. Based on the images you posted you have just a simple shifting of the PE curve and it just needs to be updated with a new PEMPro run. The original factory curve no longer fits, and that is quite normal.

Roland Christen







-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Sat, May 11, 2019 10:33 am
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



No - I do not realize many things about astronomy which is why I am asking.  Hoping to get a response without an attitude.

I enabled PEM using the AP ASCOM driver through ScarpCap, not Skysafri.  If that means it is still off, then fine, it is off.  My mistake.  Just trying to get educated.  

I can use a guider and will try.  My point has been that this has never been required in the past.  I have had decent 30-60s stacked unguided exposures for a couple of years with this mount but not anymore. 

I will also teach myself PemPro.

Thank you.
 



Ray Gralak
 

No - I do not realize many things about astronomy
which is why I am asking.
Are you imaging an object in a different part of the sky than what you usually have been? Each part of the sky can have a different drift rate, so maybe the area you are targeting just inherently has a lot of drift. The drift can come from polar alignment error, flexure in the scope, moving optics, loose or flexure in the camera mounting, refraction, etc.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Saturday, May 11, 2019 8:33 AM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



No - I do not realize many things about astronomy which is why I am asking. Hoping to get a response without
an attitude.

I enabled PEM using the AP ASCOM driver through ScarpCap, not Skysafri. If that means it is still off, then fine,
it is off. My mistake. Just trying to get educated.

I can use a guider and will try. My point has been that this has never been required in the past. I have had
decent 30-60s stacked unguided exposures for a couple of years with this mount but not anymore.

I will also teach myself PemPro.

Thank you.



Roland Christen
 

I know that often I am long winded and it may be a chore to read thru what I have written. Let me assure you that I'm not trying to dismiss your issue, and that I've seen just about every type of situation in the many many years that I've been making and testing mounts here at Astro-Physics. I can smell out a problem as well as the best bloodhound on the planet.

When you post problems on Cloudy Nights you will get many off-the-wall suggestions by helpful people, most of them not even being owners of the same mount you have. Their suggestions will have you running in every direction, chasing red herrings down blind alleys. At least on the AP user group you will get responses from actual Astro-Physics mount users.

Most helpful would be to first call or e-mail AP with your questions so that our team can analyze the info that you provide (or the info that we ask you to provide) and give you a proper direction as to what to do about it. We will do everything possible to correct whatever problem you have, and hopefully resolve it in the shortest time with the least disruption of your setup. That's the best we can do, so please guys, give our tech team a chance first before you go off on CN expecting a solution.

Roland Christen
aka Rolando



-----Original Message-----
From: chris1011@... [ap-gto]
To: ap-gto
Sent: Sat, May 11, 2019 11:10 am
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



The periodic error of a mount changes thru use because the worm and worm wheels rub against each other and thus wear. It only takes a few molecules of metal being worn off the worm to change the periodic error curve by 1 - 2 arc seconds. With your focal length a 2 arc sec error results in trailed stars, that is just fundamental fact. It may not show up with a 400mm focal length refractor, but a C11 has almost 2800mm of focal length, so every error is multiplied by a factor of 7 compared to the short scopes most imagers use.

Why does a worm wheel wear in today's mounts and not so much in the old GEMs back in the film era? The main difference is that today we do a lot of high speed slewing to get from one object to the next. The old mounts never had this capability and the worms turned so slowly that it would take a century to get the same wear that we get today running at 1200x slew speeds in one year. In fact, in those old mounts we never even greased the worms because that would attract dirt and dust, being that most of them had open gears. In today's GoTo mounts it is important to re-grease the mounts at least once a year - we have grease kits available for our mounts (call the office). Good lubrication helps to prevent excessive wear on a GoTo mount.

If you want to eliminate PE, you will have to periodically monitor your mount's periodic error with a program like PEMPro or PHD2. You can try PEMPro for free for a period of time and see if you like it. It has other features that are quite nice to have and can be used with any other mount that you have. It will definitely show the extent of the PE of your worm gear and create a very accurate curve to cancel it out so you can get back to 60 second un-trailed images.

If your worm has a major problem, PEMPro is the way to record that and will give you proof that something needs to be fixed. Just showing a 5 minute trailed image shows absolutely nothing about the state of the worm and worm wheel, whereas PEMPro can definitely pinpoint whether there is a problem or not. In my experience a frequent user of a GoTo mount will need to re-do the PE curve or at least check it every observing season (once per year up north or once every 6 months down south). Usually that's all it takes to get the PE back to 1 arc sec or less.

Can you have a damaged gear? Yes, it's possible. In a few rare instances the gears were abused and had sections on them that were damaged due to improper meshing procedure. In those cases the images showed huge trails only at certain places in the sky (at certain worm wheel angles where the damage occurred). In other parts of the sky the mount worked fine (no damage at that part of the worm wheel). This doesn't appear to be the case in your mount. Based on the images you posted you have just a simple shifting of the PE curve and it just needs to be updated with a new PEMPro run. The original factory curve no longer fits, and that is quite normal.

Roland Christen







-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Sat, May 11, 2019 10:33 am
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



No - I do not realize many things about astronomy which is why I am asking.  Hoping to get a response without an attitude.

I enabled PEM using the AP ASCOM driver through ScarpCap, not Skysafri.  If that means it is still off, then fine, it is off.  My mistake.  Just trying to get educated.  

I can use a guider and will try.  My point has been that this has never been required in the past.  I have had decent 30-60s stacked unguided exposures for a couple of years with this mount but not anymore. 

I will also teach myself PemPro.

Thank you.
 





Bruce Donzanti
 

Thanks for the advice, Ray

No- my usual areas; not too low; I usually stay at 30 degrees and higher above horizon.  However, I have not studied the drift problem in multiple areas recently.  I can easily check that out.  I checked other possible variables numerous times like PA, connections, and cables and all seem fine.  I have only one cable running down through the mount's cable management system to the laptop as the rest are neatly connected on top of the scope itself.  I realize flexure and mirror shift are possible sources of error as well, especially on the C11.  I usually do not find the mirror locks to help much but I will try them again.

Thanks again for the things to keep an eye out on. 


Bruce Donzanti
 

Thank you for the in-depth and clear explanation of things to be aware of and check.  I did the 5 min at George's request.  I think the intent was just to verify the drifting and to note if it was in RA. DEC, or both.  In any event, I will press on and figure this out. 

I will call the office next week for the grease kit.  

Thanks again,
Bruce





Roland Christen
 


I think the intent was just to verify the drifting and to note if it was in RA.
Periodic error is NOT drift. The two things are quite different. Drift is a continuous motion in one direction which eventually moves the object completely out of the field of view.

Periodic error is simply a back and forth movement of the object (or star) over a distance of about 5 - 7 arc seconds. The trail of the star movement often has a brighter point at the beginning and end of the trail, just like your 5 minute image shows. This is very characteristic of periodic error, and is not characteristic of drift, where the star trail has no brightening anywhere along the path. Judging by the number of pixels in your posted image taken with your camera, I would estimate that your periodic error is somewhere in the 5 to 7 arc sec range and seems to be quire regular. This means that a simple re-doing of the PE curve and downloading it into the CP controller will get you back to where you were before.

Now here is what I think happened when you suddenly had this "drift". I'm betting a bowl of ice cream that somehow you inadvertently erased the PE curve in the mount memory during one of your setups and you actually have no compensating curve at all. That would explain why turning the PEM on does not change anything. Because there is nothing there in memory. PEMPro can dig out what's in memory, another very useful tool of that amazing program. If that's the case, then you can be assured that nothing has happened to the mount's mechanical integrity, and I can sleep peacefully for at least one night.

Rolando


-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Sat, May 11, 2019 11:53 am
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



Thank you for the in-depth and clear explanation of things to be aware of and check.  I did the 5 min at George's request.  I think the intent was just to verify the drifting and to note if it was in RA. DEC, or both.  In any event, I will press on and figure this out. 

I will call the office next week for the grease kit.  

Thanks again,
Bruce







Bruce Donzanti
 

Understood but I contacted George via email and he is trying to help and requested the 5 min exposure you looked at.  Probably better to call next time as things through email can sometimes move an issue along at a snails pace.  Also, It is not your long-winded explanations.  In fact, some of those are the best and incredibly helpful and yes, I understand you know this stuff better than most.  In fact, I expect that and that is why I am asking for help on your mount that I bought and was thinking of getting a heavier one for my observatory.   However, I sometimes get vibes from your responses like, boy, you are an idiot.  Well, I can do the same thing if you ask me questions about what I do in my profession.  And maybe the signals I picked up are misguided and if so, I apologize for that.  That is why I also asked on CNs, realizing the danger of getting advice from someone who knows even less than me.  

Anyway, I prefer to move on and a less learned for me: call AP first and take it from there.



Bruce Donzanti
 

Got it - thank you 


On May 11, 2019, at 1:06 PM, chris1011@... [ap-gto] <ap-gto@...> wrote:

 


I think the intent was just to verify the drifting and to note if it was in RA.
Periodic error is NOT drift. The two things are quite different. Drift is a continuous motion in one direction which eventually moves the object completely out of the field of view.

Periodic error is simply a back and forth movement of the object (or star) over a distance of about 5 - 7 arc seconds. The trail of the star movement often has a brighter point at the beginning and end of the trail, just like your 5 minute image shows. This is very characteristic of periodic error, and is not characteristic of drift, where the star trail has no brightening anywhere along the path. Judging by the number of pixels in your posted image taken with your camera, I would estimate that your periodic error is somewhere in the 5 to 7 arc sec range and seems to be quire regular. This means that a simple re-doing of the PE curve and downloading it into the CP controller will get you back to where you were before.

Now here is what I think happened when you suddenly had this "drift". I'm betting a bowl of ice cream that somehow you inadvertently erased the PE curve in the mount memory during one of your setups and you actually have no compensating curve at all. That would explain why turning the PEM on does not change anything. Because there is nothing there in memory. PEMPro can dig out what's in memory, another very useful tool of that amazing program. If that's the case, then you can be assured that nothing has happened to the mount's mechanical integrity, and I can sleep peacefully for at least one night.

Rolando


-----Original Message-----
From: donzantib@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, May 11, 2019 11:53 am
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



Thank you for the in-depth and clear explanation of things to be aware of and check.  I did the 5 min at George's request.  I think the intent was just to verify the drifting and to note if it was in RA. DEC, or both.  In any event, I will press on and figure this out. 

I will call the office next week for the grease kit.  

Thanks again,
Bruce







Roland Christen
 

You raise an interesting point about vibes. Maybe it's an expression of frustration on my part and for that I apologize.

I've seen changes in the hobby from the days when it was mandatory for users to know much more about their equipment and how things actually work. In a lot of cases people built their own stuff, even the optics, and consequently had real working knowledge about how things worked. Everyone read S&T and Astronomy magazine, and they had frequent articles which went into depth on various aspects of the hobby. The articles were carefully researched and written by very knowledgeable people who actually knew their stuff. Many good books on our hobby were written and are still written but does anyone read books anymore?

Contrast that with what's happening today on the internet. Everyone gets to say their piece regardless if they know what they are talking about. The result is a helter skelter of stuff flying in all different directions, and sometimes if a false narrative is repeated by enough people it becomes truth. It is amazing how much misinformation there is on some CN posts, and every once in a while a real expert on the subject tries to help and gets banned in the process! I know several people that got banned for simply trying to clear up misconceptions. The thinking of those knowledgeable guys who are still around on CN is that you better be very gentle in your answers to people and never press your point lest you get moderated or outright banned.

That's not to say that the internet is not useful for finding out facts. There are still plenty of ways to get good info, but the great days of magazine editorial control of good information are over.

P.S. your mount issue is almost certainly that your PEM data has been inadvertently erased and thus you have a small periodic error that prevents you from getting round stars at your focal length.

Rolando



-----Original Message-----
From: donzantib@... [ap-gto]
To: ap-gto
Sent: Sat, May 11, 2019 12:10 pm
Subject: Re: [ap-gto] Re: Mach 1 tracking problem



Understood but I contacted George via email and he is trying to help and requested the 5 min exposure you looked at.  Probably better to call next time as things through email can sometimes move an issue along at a snails pace.  Also, It is not your long-winded explanations.  In fact, some of those are the best and incredibly helpful and yes, I understand you know this stuff better than most.  In fact, I expect that and that is why I am asking for help on your mount that I bought and was thinking of getting a heavier one for my observatory.   However, I sometimes get vibes from your responses like, boy, you are an idiot.  Well, I can do the same thing if you ask me questions about what I do in my profession.  And maybe the signals I picked up are misguided and if so, I apologize for that.  That is why I also asked on CNs, realizing the danger of getting advice from someone who knows even less than me.  

Anyway, I prefer to move on and a less learned for me: call AP first and take it from there.






Stelios
 

Roland, as a CN moderator, I can assure you we don't ban people for trying to clear up misconceptions. Yes, it is regrettable that a lot of misinformation and bad advice exists there, but that's the way of our present world. Blame the person who first said "everyone's entitled to their opinion"--the most destructive meme ever.

But on CN we do insist that *even if someone said something totally stupid*, and *even if someone refuses to take good advice but repeats the error he made*, people still should limit their posts to factual information and conceal their exasperation. Basically, take a couple of deep breaths and re-read post before hitting the send button--and in some cases, just don't hit that button. 

For someone's posting privileges to be curtailed, they must have made *repeated* aggressive comments, shown *repeated* exasperation, or *repeatedly* made disparaging personal remarks. Please note that this is our policy--we are not perfect, and please don't ask me to comment on any particular situation. 

The goal of the moderators is to keep the discussion civil, and the environment pleasant and welcoming--but the moderators are totally neutral as to the question of accuracy of comments. That is for the person reading to decide. A civil post that is 100% wrong is as allowable as a civil post that is 100% correct.

I might as well add my personal opinion, that you have many more supporters than detractors on CN. With good reason your products are much loved, and your service is often quoted as the best there is. 

Additionally, some of us with very high opinions of Astro-Physics, will sometimes post on CN first with an issue, because we simply don't want to waste AP's valuable time with what often is just a user "senior moment."