Guiding help

[Kevin McQuown]

Hello:

I'm not sure if this is weather and seeing related or an issue with guiding itself. Here is the link to my log file from last night.

https://openphdguiding.org/logs/dl/PHD2_logs_fotG.zip

Here are two screenshots showing a part of an image from last night.  One looking good and another looking poor.  I would say about 1/2 of my images have these small star trails always going in the same direction.

[Jim Bachesta]

For what it's worth, I had a vibration issue due to my camera's fan that caused similar star trails, that were always the same direction.  

--
You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/9e63ab58-b8bf-46c2-bdce-bca918c5bc07n%40googlegroups.com.

[Kevin McQuown]

Ah, and my setup is as follows:

ZWO AM5N Pro Mount

UltraCat 91 WIFD Astrograph

ZWO 6200MM Pro

ZWO ASI 220MM Mini guide camera

32mm UniGuide Scope

[Brian Valente]

Hi Kevin

what type of mount is this?

Here's what your logs show and some other feedback:

• after you do a calibration, you should run the Guiding Assistant. It will give you feedback on issues and also recommend minimum moves. 
• One of your runs basically had only a lost guidestar, so there wasn't any effective guiding for the ~70 minutes. You should be monitoring for this in the future.
• The other two runs shows substantial and nearly instant jumps in your RA of 50" to 75". These are enormous jumps. I'm not sure if your imaging scale, but for example if you are imaging at 1"/pixel, that is 50-75 pixel jumps. looking at your screenshots, it looks like maybe 20-30 pixels, so around 3-4"/pixel is my guess? 
  
  blue is RA, red is Dec. You can see this is not an isolated issue, but rather through your entire ~3 hour run. This suggests something significantly amiss mechanically with your RA axis:
  
  Looking at the residual error for more insight into this, there is a big 6" uncorrected error at about 96 seconds, this may better point you to the source of the problem. Depending on your mount, it could a belt/cog issue, a problem with transfer gears, gear mesh is too tight and creating stiction, or another mechanically-related issue.  It could also be more than one thing that is causing this issue.
  

When flipping to the opposite side of pier (pointing west) the issue is somewhat reduced but still present. 

As a next step doing a longer (~15-30 minute) guiding assistant run right after calibration (just switch to guiding assistant, no need to change sky position) and posting the log here will help clarify your mount's performance. 

Brian

On Mon, Jan 19, 2026 at 11:58 AM Kevin McQuown <ke...@thewcl.com> wrote:

--

You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/9e63ab58-b8bf-46c2-bdce-bca918c5bc07n%40googlegroups.com.

--

Brian 

Brian Valente

astronomy portfolio https://www.astrobin.com/users/bvalente/ 

[Kevin McQuown]

Hi Brian:

It is a ZWO AM5N

Kevin McQuown
ke...@thewcl.com

> On Jan 19, 2026, at 3:16 PM, Brian Valente <bval...@gmail.com> wrote:
>
> Hi Kevin
>
> what type of mount is this?
>
> Here's what your logs show and some other feedback:
>
> • after you do a calibration, you should run the Guiding Assistant. It will give you feedback on issues and also recommend minimum moves.
> • One of your runs basically had only a lost guidestar, so there wasn't any effective guiding for the ~70 minutes. You should be monitoring for this in the future.
> • The other two runs shows substantial and nearly instant jumps in your RA of 50" to 75". These are enormous jumps. I'm not sure if your imaging scale, but for example if you are imaging at 1"/pixel, that is 50-75 pixel jumps. looking at your screenshots, it looks like maybe 20-30 pixels, so around 3-4"/pixel is my guess?
>
> blue is RA, red is Dec. You can see this is not an isolated issue, but rather through your entire ~3 hour run. This suggests something significantly amiss mechanically with your RA axis:
>

> <image.png>Looking at the residual error for more insight into this, there is a big 6" uncorrected error at about 96 seconds, this may better point you to the source of the problem. Depending on your mount, it could a belt/cog issue, a problem with transfer gears, gear mesh is too tight and creating stiction, or another mechanically-related issue. It could also be more than one thing that is causing this issue.

> <image.png>
>
> When flipping to the opposite side of pier (pointing west) the issue is somewhat reduced but still present.
>
> As a next step doing a longer (~15-30 minute) guiding assistant run right after calibration (just switch to guiding assistant, no need to change sky position) and posting the log here will help clarify your mount's performance.
>
> Brian
>
> On Mon, Jan 19, 2026 at 11:58 AM Kevin McQuown <ke...@thewcl.com> wrote:
> Hello:
>
> I'm not sure if this is weather and seeing related or an issue with guiding itself. Here is the link to my log file from last night.
>
> https://openphdguiding.org/logs/dl/PHD2_logs_fotG.zip
>
> Here are two screenshots showing a part of an image from last night. One looking good and another looking poor. I would say about 1/2 of my images have these small star trails always going in the same direction.
>
> --
> You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/9e63ab58-b8bf-46c2-bdce-bca918c5bc07n%40googlegroups.com.
>
>
> --
> Brian
>
>
>
> Brian Valente
> astronomy portfolio https://www.astrobin.com/users/bvalente/
> --
> You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.

> To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i4DthB6FozL_-hKDKzQA1umZd4rHv%2BTAeBe13aNdKg1DA%40mail.gmail.com.

[Kevin McQuown]

Thanks for all your advice. I will run the guiding assistant in my next run, hopefully tonight.

My mount initially had some communication issues and would need a power cycle to bring back on line. ZWO sent a new motherboard which the Starfront guys replaced on site. Interestingly the mother board came with updated firmware which is actually past what they have published as the latest. Could this be a firmware issue?

As a note, I guided very well before the board change.

Kevin McQuown
ke...@thewcl.com



> On Jan 19, 2026, at 3:16 PM, Brian Valente <bval...@gmail.com> wrote:
>

> Hi Kevin
>
> what type of mount is this?
>
> Here's what your logs show and some other feedback:
>
> • after you do a calibration, you should run the Guiding Assistant. It will give you feedback on issues and also recommend minimum moves.
> • One of your runs basically had only a lost guidestar, so there wasn't any effective guiding for the ~70 minutes. You should be monitoring for this in the future.
> • The other two runs shows substantial and nearly instant jumps in your RA of 50" to 75". These are enormous jumps. I'm not sure if your imaging scale, but for example if you are imaging at 1"/pixel, that is 50-75 pixel jumps. looking at your screenshots, it looks like maybe 20-30 pixels, so around 3-4"/pixel is my guess?
>
> blue is RA, red is Dec. You can see this is not an isolated issue, but rather through your entire ~3 hour run. This suggests something significantly amiss mechanically with your RA axis:
>

> <image.png>Looking at the residual error for more insight into this, there is a big 6" uncorrected error at about 96 seconds, this may better point you to the source of the problem. Depending on your mount, it could a belt/cog issue, a problem with transfer gears, gear mesh is too tight and creating stiction, or another mechanically-related issue. It could also be more than one thing that is causing this issue.

> <image.png>
>
> When flipping to the opposite side of pier (pointing west) the issue is somewhat reduced but still present.
>
> As a next step doing a longer (~15-30 minute) guiding assistant run right after calibration (just switch to guiding assistant, no need to change sky position) and posting the log here will help clarify your mount's performance.
>
> Brian
>
> On Mon, Jan 19, 2026 at 11:58 AM Kevin McQuown <ke...@thewcl.com> wrote:
> Hello:
>
> I'm not sure if this is weather and seeing related or an issue with guiding itself. Here is the link to my log file from last night.
>
> https://openphdguiding.org/logs/dl/PHD2_logs_fotG.zip
>
> Here are two screenshots showing a part of an image from last night. One looking good and another looking poor. I would say about 1/2 of my images have these small star trails always going in the same direction.
>
> --
> You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/9e63ab58-b8bf-46c2-bdce-bca918c5bc07n%40googlegroups.com.
>
>
> --
> Brian
>
>
>
> Brian Valente
> astronomy portfolio https://www.astrobin.com/users/bvalente/
> --
> You received this message because you are subscribed to the Google Groups "Open PHD Guiding" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to open-phd-guidi...@googlegroups.com.

> To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i4DthB6FozL_-hKDKzQA1umZd4rHv%2BTAeBe13aNdKg1DA%40mail.gmail.com.

[Brian Valente]

This is pretty surprising results from a strainwave mount

A guiding assistant run and uploading the logs is a good next step

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/2A79D4B7-936E-4D88-8B33-4886BD19928A%40thewcl.com.

[Brian Valente]

PS

>>>  Could this be a firmware issue?

There's no way to tell that from the guidelogs. However, you can send them the results from your guidelog that I posted back to you and ask why you are getting such huge spikes with the new board and firmware. Indicate you did not have these issues before. 

 

They may have

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/E6C5FBCB-CB2E-45E7-B5AA-EC925B0F076D%40thewcl.com.

[Kevin McQuown]

Just a quick FYI.  ZWO confirmed an issue with the RA drive. It is a known issue.  I am sending in for repair. Sigh.  Thanks for your help on this and what you supplied was perfect to send to ZWO for a quick identification of the issue.

[Brian Valente]

Thanks for the update Kevin. It happens, and fortunately ZWO is stepping up to address it. 

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/2d1c2aba-f427-4c31-8ae2-d40e1546ba63n%40googlegroups.com.