PHD2 guiding and tracking errors. Help !!!

[johngm]

1 minute ago, johngm said:

Yes Newbie, I think it was your post I read regarding the focal length. But like you said, I doubt it would make a significant difference. As for the focus, its spot on with pin point stars in the FOV, and its locked down with the locking collar. I was guiding fine with it Monday.

John

I meant to ask you, was you experiencing the same issue as ive described ?

[Thalestris24]

1 hour ago, johngm said:

Exactly right Louise, the mount would have moved quite a bit. There were plenty of stars in the FOV when I started. I will take your advice and set exposure to around 2. As regarding what you said about about pulse guiding, that was on my to do list. Also checking that its not selecting a hot pixel, although I did a reset and added a New Dark at one point, but it is another avenue to explore. I have Just looked in PHD2, how do you manually select guide star ?

John

After a successful calibration you just click on the looping button (with auto select off, of course) then look for a suitable guide star near your imaging target, then just click on it. Then click on the guide button. Look for a star that hives high snr (.100 is good) but that doesn't saturate. The star profile tool is useful for selecting and monitoring a guide star. If using ST4 you have to recalibrate if you move to a different target/different part of the sky. Obviously something has changed in your setup since you last had things working ok with ST4. Using pulse guiding has lots of advantages - you don't have to calibrate each session as PHD2 can store the calibration data and re-use it. Similarly you don't have to recalibrate for different parts of the sky.

Louise

ps do make a darks library / bad pixel map. It will give you a much cleaner display and minimize the chances of selecting a hot pixel

[newbie alert]

1 hour ago, johngm said:

Yes Newbie, I think it was your post I read regarding the focal length. But like you said, I doubt it would make a significant difference. As for the focus, its spot on with pin point stars in the FOV, and its locked down with the locking collar. I was guiding fine with it Monday.

John

Looks like a power issue to me If I was to have a guess

[kens]

My first guess after a quick look at the calibration (which was unsuccessful) is that the mount seems to be rotating in the wrong direction. That is it is set up for the southern hemisphere instead of the north.

[SteveA]

I would suspect the ST4 cable is bad.

Its definitely worth trying a new cable before getting into more complicated potential causes. It has always amazed me how often IT issues can be solved by using a new cable and I've had several occasions with my astro setup where USB cables are the route cause of problems.

Steve

[SteveA]

Or....of course try pulse guiding, this would eliminate both the potential for a dodgy ST4 cable and also the ST4 ports on the camera and the mount.

Steve

[johngm]

2 hours ago, newbie alert said:

Looks like a power issue to me If I was to have a guess

I have already dug out my 6 amp power supply to try, infact I will use that from now on.

John

[johngm]

Hi Steve, thanks for the input. Louise has already Suggested trying pulse guiding instead of the ST4 Port, so that is on my list, and I know what you mean regarding IT stuff, working on networking myself. I've checked the obvious like making sure there are no bent pins in the port. I will checked the cable with my multimeter make sure I have nothing shorting out or open circuit. 

It looks like I'm going to have time to do these sanity checks now, because the blooming clouds have moved in

John

[johngm]

2 hours ago, kens said:

My first guess after a quick look at the calibration (which was unsuccessful) is that the mount seems to be rotating in the wrong direction. That is it is set up for the southern hemisphere instead of the north.

Hi Ken, all my parameters are correct. Set for north, and GPS coordinates set, and as I said in the opening of the post, it was ok on Monday. Thanks for checking that for me.

John

[johngm]

Hi Everyone, It looks like I'm going to have to wait again, that good old reliable UK weather

Still, some good news has come out of my frustrations, My new tripod arrived from FLO for my Skywatcher Star Adventurer. Its a really sturdy tripod and will fit in my suitcase for our trip to La Palma in a couple of weeks time. I will leave a review and link on here. Well, looks like i'll have plenty of time now with the weather !!!!

John

[kens]

Here's what really happened in your calibration. As you can see all the movement is nearly all in one direction only instead of an L shape. The first thing you need to work out is whether that movement is in RA or Dec. My first thought was RA as it is moving slower  with westward pulses and faster with eastward ones. In north /south the motion is constant but there is hardly any orthogonal movement. There is a bit of a reversal after the backlash removal leg and a bit of an orthogonal movement right at the end of the north leg.

So, if that constant motion is in RA then you have a problem with your Dec axis hardly moving and with a constant motion (relative to the guide star) in RA.

The westward leg  is calculated by PHD2 as 2.134 px/sec at a scale of 4.77 arcsec/px which gives 10.2 arcsec/sec. 

The "north" leg  is calculated as  2.691 px/sec which gives 12.8 arcsec/sec

I can also calculate the eastward leg as 34.5 arcsec/sec which is more than 2x sidereal.

So the RA guiding does appear to be doing "something" as the east and west legs are at different speeds. Now when a mount moves east, it normally just stops tracking (to avoid backlash) or if the guide rate is less than 1x it slows down the tracking. At dec 0 the tracking rate is at its maximum of 15 arcsec/sec  versus the 34.5 arcsec/sec you are seeing. That can only happen if the RA motor is actually driving the mount eastward. With ST4 guiding there are 4 wires to guide N,S,E and W. I wonder if the E and W wires are crosssed over in your ST4 cable .  

A couple of bits of information that would help with the analysis: What declination (roughly) were you calibrating at and how is your guide camera oriented? e.g have you set it up so RA is left/right or is it just random? Also, next time you do a calibration, turn OFF the "Fast recenter" option on the guiding tab of the brain. Make sure you calibrate near dec 0 and record the declination. With ST4 guiding PHD2 does not record the declination. You may also want to try a Star Cross test on the Tools menu.

So your options are to replace the ST4 cable and preferably move to pulse guiding. This may or may not fix the proble - e.g it could bethe motor controller. You could also gather some more information for analysis. You don't need a perfectly clear night. All you need is one start to guide on near dec 0 for a few minutes while you do a star cross test and a calibration.  You could also try an unguided run for a few minutes but with this amount of movement as you may lose the guide star.

[johngm]

14 hours ago, kens said:

Here's what really happened in your calibration. As you can see all the movement is nearly all in one direction only instead of an L shape. The first thing you need to work out is whether that movement is in RA or Dec. My first thought was RA as it is moving slower  with westward pulses and faster with eastward ones. In north /south the motion is constant but there is hardly any orthogonal movement. There is a bit of a reversal after the backlash removal leg and a bit of an orthogonal movement right at the end of the north leg.

So, if that constant motion is in RA then you have a problem with your Dec axis hardly moving and with a constant motion (relative to the guide star) in RA.

The westward leg  is calculated by PHD2 as 2.134 px/sec at a scale of 4.77 arcsec/px which gives 10.2 arcsec/sec. 

The "north" leg  is calculated as  2.691 px/sec which gives 12.8 arcsec/sec

I can also calculate the eastward leg as 34.5 arcsec/sec which is more than 2x sidereal.

So the RA guiding does appear to be doing "something" as the east and west legs are at different speeds. Now when a mount moves east, it normally just stops tracking (to avoid backlash) or if the guide rate is less than 1x it slows down the tracking. At dec 0 the tracking rate is at its maximum of 15 arcsec/sec  versus the 34.5 arcsec/sec you are seeing. That can only happen if the RA motor is actually driving the mount eastward. With ST4 guiding there are 4 wires to guide N,S,E and W. I wonder if the E and W wires are crosssed over in your ST4 cable .  

A couple of bits of information that would help with the analysis: What declination (roughly) were you calibrating at and how is your guide camera oriented? e.g have you set it up so RA is left/right or is it just random? Also, next time you do a calibration, turn OFF the "Fast recenter" option on the guiding tab of the brain. Make sure you calibrate near dec 0 and record the declination. With ST4 guiding PHD2 does not record the declination. You may also want to try a Star Cross test on the Tools menu.

So your options are to replace the ST4 cable and preferably move to pulse guiding. This may or may not fix the proble - e.g it could bethe motor controller. You could also gather some more information for analysis. You don't need a perfectly clear night. All you need is one start to guide on near dec 0 for a few minutes while you do a star cross test and a calibration.  You could also try an unguided run for a few minutes but with this amount of movement as you may lose the guide star.

Hi Ken,

Thanks for all that information/Advice. Anyway, a quick update on how far ive got, which involves a lot of what you've written.

Last night, like I said in my last post on this, sods law, the clouds rolled in. So, I took the missus for dinner. When we got back home, I looked up, Stars !!!!. Anyway, set up my mount with the 6 amp power supply (to eliminate PS issues). Left the original ST4 rj12 cable as is. Did the Alignment routine, and sent the mount to NGC 2237. I am not sure on the declination of this ken, but it just above the celestial equator viewed from the UK and the time I was tracking, in SSE direction but far enough away from the meridian. I then fired up PHD2, corrected the focal length parameter, and connected the camera and began looping at 2.5s. The stars in the FOV were pretty stationary. I then manually selected a guide star (to eliminate hot pixel guiding). So, clicked calibrate, and it began is west calibration, and of it went and the stars were moving in Left to right in PHD. Then it started is east calibration step, but continued going west, but you could actually see it pausing  when it was sending the signal to the mount, but then just carried on west, and then reporting calibration error.

Next step, I swapped the RJ12 cable for another one I had, and exactly the same thing was happening. Next stage was to plug in my HC to my laptop, and start pulse guiding. Guess what, them damn clouds came back in :(.

My conclusions so far:

Not a power supply issue. Not a hot pixel tracking issue. Not a cabling issue. I am going along the lines now of what you mentioned ken, that it could possibly be a controller board issue.

It has been raining today, but the Sun is starting to break through the clouds, so, I'm hoping it clears up tonight to try pulse guiding.

It seems very strange that the stars in the FOV of my guide camera are steady, until the mount receives a signal from PHD to calibrate, then sets it off with a mind of its own, this is why I'm also thing control board issue.

John

[Thalestris24]

Hi John

I think I'd suspect the ST4 outputs from your guide cam. I had a very similar problem when trying to setup my qhy5l-ii under Linux/lin-guider. In that case there were options to set in the software to select which individual ST4 outputs for which ST4 cable wire. Selecting the wrong ones and the mount went shooting off - just like yours! I'm wondering whether your camera is installed correctly in the first place? You have the latest PHD2 so that's ok. I'm afraid I'm not actually familiar with ZWO cameras or their drivers... Are you running the Ascom platform? Normally the 'Ascom' version of a camera driver is the best one to use. Is the camera settings tool available in PHD2 (via the connect screen)? I wonder what options it gives you? I've noticed that there is more than one version of the mono asi120mm driver (MT9M034 mono sensor same as the qhy5l-iim) - a native one, an ascom one, and a USBST4 ASCOM Driver - are you definitely running and selecting that? It might make all the difference! I suspect the st4 driver makes sure you're running in 8bit mode with the other 4 bits available and correctly configured for ST4 mode...

Louise

[SteveA]

1 hour ago, johngm said:

Hi Ken,

Thanks for all that information/Advice. Anyway, a quick update on how far ive got, which involves a lot of what you've written.

Last night, like I said in my last post on this, sods law, the clouds rolled in. So, I took the missus for dinner. When we got back home, I looked up, Stars !!!!. Anyway, set up my mount with the 6 amp power supply (to eliminate PS issues). Left the original ST4 rj12 cable as is. Did the Alignment routine, and sent the mount to NGC 2237. I am not sure on the declination of this ken, but it just above the celestial equator viewed from the UK and the time I was tracking, in SSE direction but far enough away from the meridian. I then fired up PHD2, corrected the focal length parameter, and connected the camera and began looping at 2.5s. The stars in the FOV were pretty stationary. I then manually selected a guide star (to eliminate hot pixel guiding). So, clicked calibrate, and it began is west calibration, and of it went and the stars were moving in Left to right in PHD. Then it started is east calibration step, but continued going west, but you could actually see it pausing  when it was sending the signal to the mount, but then just carried on west, and then reporting calibration error.

Next step, I swapped the RJ12 cable for another one I had, and exactly the same thing was happening. Next stage was to plug in my HC to my laptop, and start pulse guiding. Guess what, them damn clouds came back in :(.

My conclusions so far:

Not a power supply issue. Not a hot pixel tracking issue. Not a cabling issue. I am going along the lines now of what you mentioned ken, that it could possibly be a controller board issue.

It has been raining today, but the Sun is starting to break through the clouds, so, I'm hoping it clears up tonight to try pulse guiding.

It seems very strange that the stars in the FOV of my guide camera are steady, until the mount receives a signal from PHD to calibrate, then sets it off with a mind of its own, this is why I'm also thing control board issue.

John

I tend to agree with Louise, in that it does look more like the output from the camera rather than the mount. I take it that the mount does't exhibit any peculiar reactions to manual slew requests that you issue? Assuming it doesn't I can't see it being the controller on the mount. Mind you I'm wrong about most things...so who knows!

Needless to say I'll be very interested to hear how you get on with this little problem..

Steve

[johngm]

1 hour ago, Thalestris24 said:

Hi John

I think I'd suspect the ST4 outputs from your guide cam. I had a very similar problem when trying to setup my qhy5l-ii under Linux/lin-guider. In that case there were options to set in the software to select which individual ST4 outputs for which ST4 cable wire. Selecting the wrong ones and the mount went shooting off - just like yours! I'm wondering whether your camera is installed correctly in the first place? You have the latest PHD2 so that's ok. I'm afraid I'm not actually familiar with ZWO cameras or their drivers... Are you running the Ascom platform? Normally the 'Ascom' version of a camera driver is the best one to use. Is the camera settings tool available in PHD2 (via the connect screen)? I wonder what options it gives you? I've noticed that there is more than one version of the mono asi120mm driver (MT9M034 mono sensor same as the qhy5l-iim) - a native one, an ascom one, and a USBST4 ASCOM Driver - are you definitely running and selecting that? It might make all the difference! I suspect the st4 driver makes sure you're running in 8bit mode with the other 4 bits available and correctly configured for ST4 mode...

Louise

 

54 minutes ago, SteveA said:

I tend to agree with Louise, in that it does look more like the output from the camera rather than the mount. I take it that the mount does't exhibit any peculiar reactions to manual slew requests that you issue? Assuming it doesn't I can't see it being the controller on the mount. Mind you I'm wrong about most things...so who knows!

Needless to say I'll be very interested to hear how you get on with this little problem..

Steve

Hi Louise, Steve.

I'm going to try the Pulse guiding tonight you both suggested, suns come out . The strange thing is, it was working ok on Monday, and I haven't modified any camera settings with the ZWO. Unless there is a Camera issue suddenly reared it head. I do have my Old SPC900 I could use to try if all else fails. This works OK with pulse guiding I used to use it before the ASI120MM. 

I will keep everyone informed on my progress. I'm determined to get to the bottom of this. Astronomy can be so frustrating at times lol. But thanks to people like yourselves, it great to get feedback.

Thanks John

[Thalestris24]

45 minutes ago, johngm said:

 

Hi Louise, Steve.

I'm going to try the Pulse guiding tonight you both suggested, suns come out . The strange thing is, it was working ok on Monday, and I haven't modified any camera settings with the ZWO. Unless there is a Camera issue suddenly reared it head. I do have my Old SPC900 I could use to try if all else fails. This works OK with pulse guiding I used to use it before the ASI120MM. 

I will keep everyone informed on my progress. I'm determined to get to the bottom of this. Astronomy can be so frustrating at times lol. But thanks to people like yourselves, it great to get feedback.

Thanks John

Hi

Pulse guiding with asi120mm should work ok as it uses the usb-serial cable to send guide corrections rather than the ST4. So which camera driver have you been using?

Louise

[kens]

NGC2337 is at declination of 44 degrees so not ideal as the RA movement is only 70% of what it would be at dec 0. Nevertheless, please attach your guide log.

Certainly, if pulse guiding is an option then use that. If nothing else it is easier to diagnose problems as it provides much more information in the logs.

Given the nature of this problem, I think a manual guide test would be most useful. Under the Tools menu select the Manual Guide option. Also open up your Star Profile under the View menu - this makes it easier to see small movements. Choose a pulse duration about 4 times the calibration pulse size. This will cause the star to move about 10 pixels which should be visible without the star moving outside the green box. Click each of the direction buttons and see what happens. Ideally, if you can orient the camera so that RA and Dec are aligned to the camera axes that would be helpful. To align up/down with north/south: with the mount in the home position (dec 90, counterweight down) orient the camera so that the vertical axis of the camera sensor is pointing left/right. Also, its best to conduct this test near dec 0. As a guide, Orion's belt is near dec 0 and  is well placed at this time of year.

This lets you control the test and will give you a direct view of what is going on. Then you can change things around and try again to see if it helps.

 

[ChrisEll]

On 2/15/2018 at 23:35, johngm said:

Hi fellow stargazers,

I hope someone can help me with my problem. 

Probably nothing to do with your issue but that's the kind of graph I get if I rotate the guide cam or OAG and forget to re-calibrate.

[Tommohawk]

FWIW I had to abandon ST guiding because of a controller board fault in one axis. But you say it was ok at outset so this is probably a red herring.

If using PHDs autoselect star feature it will routinely select star with SNR around 20. This does seem low, but would probably give better guiding. As you are having grief for the time being best select star with higher SNR, say 50.

Your approach is good and lots of advice here so I'm sure you are close to figuring it out - stick with it! 

[johngm]

SOLUTION FOUND !!!

Hi All fellow stargazers, and I am sorry I am so long in getting back to this post. Unfortunately, my job has taken me overseas the past 18 months, so I hadn't been able to conclude my problem. But after arriving back home the last month, and some clear skies, I was able to pursue my issue. Having tried all the advice given here, even pulse guiding, the issue was still occurring. I even took the drastic action of buying a new motor control board, but the problem still occurred.

As the issue was occurring during calibration routine, and on the west step, but continuing west when it tried to calibrate east, I had the idea, maybe it was an RA encoder/motor issue. So, my next step was to check the encoder, and swap around the RA and DEC motors. Encoder was good, but swapped the motors around anyway. The issue still occurred.

Now, at my whit's end, and about to have an expensive paper weight, I decided to contact Ed Thomas at Deepsky products, who I recently purchased a hypertune  DVD to hypertune my mount in the event I fix it. Ed has a lot of experience with Celestron CGEM mounts, and he has been very helpful and replied immediately (time difference allowing) Thanks so much Ed for your advice. He said he had heard off other CGEM users who had been having issues with PHD2. He suggested the following;

Try a different guiding package, a factory reset of the Mount. and failing this, re-flashing the firmware.

So, I had an old XP laptop with PHD v1.4 on it, so, decided to try this, and guess what ? ………… It Worked !!!, a definite hallelujah moment.  But, this didn't seem right, so I then installed PHD2 on my XP laptop, and low and behold, that worked to. So, I then connected the mount back to my windows 10 64bit  laptop  and the problem re-occurred. 

The Conclusion.  There appears to be a software issue, when connecting PHD2 guiding to a Celestron CGEM mount using a Windows 10 laptop with 64bit architecture. 

Just one thing to add, it also guides now on my XP laptop via ST4 if I choose to go down that route. I also think this is CGEM specific (maybe a firmware clash), because I tried guiding with my Skywatcher SA and this didn't pose an issue. 

I hope this maybe of use to anyone else who may be experiencing PHD2 guiding issues with a Celestron CGEM, especially connected to Windows 10.

And, once again thanks for all your fantastic input, now I can start doing the thing I love, clouds permitting !!! ?

 

John

 

[tooth_dr]

7 minutes ago, johngm said:

SOLUTION FOUND !!!

Hi All fellow stargazers, and I am sorry I am so long in getting back to this post. Unfortunately, my job has taken me overseas the past 18 months, so I hadn't been able to conclude my problem. But after arriving back home the last month, and some clear skies, I was able to pursue my issue. Having tried all the advice given here, even pulse guiding, the issue was still occurring. I even took the drastic action of buying a new motor control board, but the problem still occurred.

As the issue was occurring during calibration routine, and on the west step, but continuing west when it tried to calibrate east, I had the idea, maybe it was an RA encoder/motor issue. So, my next step was to check the encoder, and swap around the RA and DEC motors. Encoder was good, but swapped the motors around anyway. The issue still occurred.

Now, at my whit's end, and about to have an expensive paper weight, I decided to contact Ed Thomas at Deepsky products, who I recently purchased a hypertune  DVD to hypertune my mount in the event I fix it. Ed has a lot of experience with Celestron CGEM mounts, and he has been very helpful and replied immediately (time difference allowing) Thanks so much Ed for your advice. He said he had heard off other CGEM users who had been having issues with PHD2. He suggested the following;

Try a different guiding package, a factory reset of the Mount. and failing this, re-flashing the firmware.

So, I had an old XP laptop with PHD v1.4 on it, so, decided to try this, and guess what ? ………… It Worked !!!, a definite hallelujah moment.  But, this didn't seem right, so I then installed PHD2 on my XP laptop, and low and behold, that worked to. So, I then connected the mount back to my windows 10 64bit  laptop  and the problem re-occurred. 

The Conclusion.  There appears to be a software issue, when connecting PHD2 guiding to a Celestron CGEM mount using a Windows 10 laptop with 64bit architecture. 

Just one thing to add, it also guides now on my XP laptop via ST4 if I choose to go down that route. I also think this is CGEM specific (maybe a firmware clash), because I tried guiding with my Skywatcher SA and this didn't pose an issue. 

I hope this maybe of use to anyone else who may be experiencing PHD2 guiding issues with a Celestron CGEM, especially connected to Windows 10.

And, once again thanks for all your fantastic input, now I can start doing the thing I love, clouds permitting !!! ?

 

John

 

Brilliant John. Nice to have a problem wrapped up and the solution visible for other forum users. 

[johngm]

4 minutes ago, tooth_dr said:

Brilliant John. Nice to have a problem wrapped up and the solution visible for other forum users. 

Yes, it was definitely a great moment. And like you said, I hope it will help others who maybe experiencing similar issues. I have myself, found many a solution to different issues from fellow members posts on here. SGL is a great tool and great community.

John

[Stub Mandrel]

Glad you found a solution of sorts. Seems odd though as PHD2 is clearly working under W10 here? All I can say is that PHD2 is full of bear traps!
 

[Hallingskies]

Windows 10.  Enough said.  I am desperately trying to avoid it, and dreading the day that my XP laptop, XP desktop, Vista laptop or Win7 obbo desktop finally falls over...

[Yearofthegoat]

Great to see a thread followed up - and of course a solution found. I've read several threads today where the OP hasn't come back with what happened

(Had a similar thing with PHD2 and my guide camera - works in 2.6.3 but not 2.6.5. Had me going for quite a while).

On 12/10/2018 at 21:12, Hallingskies said:

Windows 10.  Enough said.  I am desperately trying to avoid it, and dreading the day that my XP laptop, XP desktop, Vista laptop or Win7 obbo desktop finally falls over...

Windows 10 being steadfastly avoided here also! Have mainly Windows 8.1 but also WinXP, Vista and Ubuntu, just for laughs (and reading NAS hard drives).