#1  
Old 16-07-2019, 07:03 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Runaway Tracking

Hi All,
Don't know if anyone can shine any light on this problem I have with my EQ6 mount using PHD2 and EQMod.

I cannot lock onto a star, even in sidereal mode when using PHD2! The star keeps moving on its own, its like the mount cannot keep up with it! And because of this I cannot calibrate to finish off my polar alignment.

The scope is balanced and all parameters are set accordingly.

Polar alignment is fairly close, Mount is level, dec is set to my location and is roughly pointing south.

I have uploaded a small video to Youtube.

https://youtu.be/xQ0FWyntLm4

Can anyone think of anything to check?

Paul
Reply With Quote
  #2  
Old 16-07-2019, 07:17 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
Mount tracking the right direction? Try stopping the tracking and see if the speed the star moves at slows down.
Reply With Quote
  #3  
Old 16-07-2019, 08:28 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Quote:
Originally Posted by The_bluester View Post
Mount tracking the right direction? Try stopping the tracking and see if the speed the star moves at slows down.
Thanks Paul, I have also done what you have mentioned and still have this issue...driving me mad!

It was a bit on the windy side but I'd dare say it would cause this issue??

Paul
Reply With Quote
  #4  
Old 16-07-2019, 10:18 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
By the video I assume you are using ASCOM with EQMOD and an EQdirect cable to drive the mount? I have never tried reversing it but I assume EQMOD sets the mount tracking direction based on the GPS coordinates you input, you have not got a North lattitude input in EQMOD setup have you?

Also, try setting the slew rate up a bit and manually slewing north and south while seeing what the star does (And east/west for that matter) If you are way off in polar alignment the star can move pretty quickly depending on your guider setup and unless you already know what axis in the guider is RA and what is Dec you can chase the wrong error.

Have you tried setting up with the hand controller instead of EQMOD? If you are using ST4 guiding PHD would still calibrate normally but if it is pulse guiding then that won't work obviously, but if it tracks properly to keep the guide stars reasonably still in the guide camera frame using the hand controller then it narrows it down to an EQMOD setup issue versus a mechanical issue or big polar alignment error.

The only time I ever saw something like that was when I had a mechanical issue with my mount and it literally was not tracking though the RA motor was running normally so the encoder said it was tracking fine.
Reply With Quote
  #5  
Old 16-07-2019, 10:21 PM
billdan's Avatar
billdan (Bill)
Registered User

billdan is offline
 
Join Date: Mar 2012
Location: Narangba, SE QLD
Posts: 1,305
Sounds like Polar Alignment not correct to me. Chances are the star is running away in DEC and goes outside the PHD green box and then guiding stops (lost star error).
It doesn't take much to be off in the Polar Alignment for the stars to race away in Declination.
I've never used EQMOD so I can't help you with that.
Reply With Quote
  #6  
Old 17-07-2019, 08:58 AM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Quote:
Originally Posted by The_bluester View Post
By the video I assume you are using ASCOM with EQMOD and an EQdirect cable to drive the mount? I have never tried reversing it but I assume EQMOD sets the mount tracking direction based on the GPS coordinates you input, you have not got a North lattitude input in EQMOD setup have you?

Also, try setting the slew rate up a bit and manually slewing north and south while seeing what the star does (And east/west for that matter) If you are way off in polar alignment the star can move pretty quickly depending on your guider setup and unless you already know what axis in the guider is RA and what is Dec you can chase the wrong error.

Have you tried setting up with the hand controller instead of EQMOD? If you are using ST4 guiding PHD would still calibrate normally but if it is pulse guiding then that won't work obviously, but if it tracks properly to keep the guide stars reasonably still in the guide camera frame using the hand controller then it narrows it down to an EQMOD setup issue versus a mechanical issue or big polar alignment error.

The only time I ever saw something like that was when I had a mechanical issue with my mount and it literally was not tracking though the RA motor was running normally so the encoder said it was tracking fine.
Thanks again Paul for your valued input.

Yes I'm running Ascom and EQMod via a serial to USB.
I thought about my coordinates and rechecked them yesterday before dark and all seemed to be correct, will check the slew rate.

Thinking now about a mechanical error, I did set off an imaging run last week when my polar align I thought was close, and left the scope for a little while to do its thing, on my return I found the tube against the pier whilst guiding! (I was attempting short exposures of Cen A) Would this have done any damage to the gears? The next couple of nights after, it was running fine without problems as I was using one of the polar alignment apps in PHD2 to align and it was holding fine, It was not until a couple of days ago I totally reset the mount using a compass app and inclination app on my phone to get the mount in the ball park to further and hopefully correct the alignment. Is the dec scale on this mount gospel? And would we trust the phone apps?

After updating the mount using the phone apps and dec scale on the mount
and using Polar Drift Align in PHD2 was showing a well off PA err of between 700 to 900! Could this be the problem of the runaway star?

Quote:
Originally Posted by billdan View Post
Sounds like Polar Alignment not correct to me. Chances are the star is running away in DEC and goes outside the PHD green box and then guiding stops (lost star error).
It doesn't take much to be off in the Polar Alignment for the stars to race away in Declination.
I've never used EQMOD so I can't help you with that.
Thanks Bill, as mentioned to Paul above, getting and hoping on the 50/50 chance of recovery eg Mechanical or Polar Align!

Last edited by peeb61; 17-07-2019 at 01:40 PM.
Reply With Quote
  #7  
Old 17-07-2019, 10:48 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
A quick check to make sure it is tracking, and you can do this in daylight. Point the scope east and horizontal (So nothing will hit the tripod for a good long while, but make sure it is pointed nowhere near the sun) and turn on tracking in EQMOD. Give it half an hour and it should have moved visibly.

Quote:
I did set off an imaging run last week when my polar align I thought was close, and left the scope for a little while to do its thing, on my return I found the tube against the pier whilst guiding
How far from the pier was it to start with and how long were you away? Just trying to work out if it was normal tracking that has put it up against the pier. Doing damage or not could depend on how tight the RA clutch was, being the difference between the clutch slipping or stalling the motor.

Either way, have you got mount limits turned on in EQMOD? It is worth doing. Mine stops the mount about 20 minutes after the meridian which gives me about half an hour worth of clearance to the tripod leg at the least favourable Dec. Same on the other side so it wont point more than about 20 minutes to the east with the scope on the west of the pier, likewise it limits at the horizon though that is not much of an issue.
Reply With Quote
  #8  
Old 17-07-2019, 11:24 AM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Quote:
Originally Posted by The_bluester View Post
A quick check to make sure it is tracking, and you can do this in daylight. Point the scope east and horizontal (So nothing will hit the tripod for a good long while, but make sure it is pointed nowhere near the sun) and turn on tracking in EQMOD. Give it half an hour and it should have moved visibly.



How far from the pier was it to start with and how long were you away? Just trying to work out if it was normal tracking that has put it up against the pier. Doing damage or not could depend on how tight the RA clutch was, being the difference between the clutch slipping or stalling the motor.

Either way, have you got mount limits turned on in EQMOD? It is worth doing. Mine stops the mount about 20 minutes after the meridian which gives me about half an hour worth of clearance to the tripod leg at the least favourable Dec. Same on the other side so it wont point more than about 20 minutes to the east with the scope on the west of the pier, likewise it limits at the horizon though that is not much of an issue.
Thanks Paul, I have slewed the scope to alpha leo and will leave that and see how it goes.

The scope was pretty close to the pier, the tube was facing up as Cen A was high in the sky, given the fact the clutch was fairly tight. It was up against the pier for a while so now I'm assuming motor stalling?

Can you get me a screen grab of your settings for your mount limits if you don't mind? Would love to set it the same as yours. mine was turned off.

Many thanks again.
Paul
Reply With Quote
  #9  
Old 17-07-2019, 11:43 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
Regards setting the limits, it is best to do them yourself rather than copy someone elses. If you turn them on the default settings will stop it at the meridian pointed from either side which should be safe, it will also stop slews that will point below the horizon.

You need to update the limits with real pointing, so if the scope is on the west side of the pier pointed east the mount limits will stop it at the meridian, you then slew 5 or 10 minutes or so to the west of the meridian manually (Depending on your setup) and update that limit, then you need to ask it to point say 15 minutes west of the meridian (Which should make it flip so the scope is on the east of the pier, pointing west) and manually slew it back some minutes east of the meridian to set that limit.

Pointed at the meridian is generally safe but I set mine up with a bit of extra pointing range as my setup does automated flips and I have seen it hit the limit and stop itself in the middle of a flip, which is a bit irritating if you expect 6 hours of data for the night and get about three as it has gotten scared and stopped mid flip.
Reply With Quote
  #10  
Old 17-07-2019, 02:36 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Hi Paul,

Looks like it is tracking, over the given hours is has moved significantly in only sidereal mode so looks like its the alignment?
I had a look at the values in the Pulse Guide Settings in EQMod, I have attached them, is there anything I should change here? Are you using EQMod?

And yes you are right about the limits, will sent mine to my own setup.

Thanks for all your help with this!

Paul
Attached Thumbnails
Click for full-size image (ASCOM Pulse Guiding.jpg)
128.9 KB13 views
Reply With Quote
  #11  
Old 17-07-2019, 03:01 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
I am using EQmod with the Orion version of the AZEQ6. I set the guide rates to their maximum in EQmod. When you calibrate PHD2 it works the guide rates out based on what you set. If you change them it will probably ask you to either change them back or recalibrate.
Reply With Quote
  #12  
Old 17-07-2019, 05:11 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Quote:
Originally Posted by The_bluester View Post
I am using EQmod with the Orion version of the AZEQ6. I set the guide rates to their maximum in EQmod. When you calibrate PHD2 it works the guide rates out based on what you set. If you change them it will probably ask you to either change them back or recalibrate.
Gotcha' thanks Paul for all your help with this, I have ruled out a lot and I think its down to polar align, not going to happen tonight as the winds have picked up again!

Paul
Reply With Quote
  #13  
Old 17-07-2019, 05:21 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 1,980
If you can afford one and can see the pole where you set up I would seriously recommend a Polemaster camera. Once you get the hang of it it turns polar alignment into a 5 minute job, with a drift align check in PHD afterwards if you want.


If you can focus on something and get a short enough exposure in daylight to see an object like a tree, do that with tracking off then slew around at a low slewing speed both in RA and dec, it will let you see easily which axis is which so you will be able to work out if it is running away in Dec due to polar alignment or has an RA tracking issue.

Last edited by The_bluester; 18-07-2019 at 10:40 AM.
Reply With Quote
  #14  
Old 18-07-2019, 10:26 AM
Nikolas's Avatar
Nikolas (Nik)
Dazed and confused

Nikolas is offline
 
Join Date: May 2012
Location: Melbourne
Posts: 1,201
I second the polemaster, 5 minutes and you are polar aligned.
Reply With Quote
  #15  
Old 29-07-2019, 09:28 AM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
My polar alignment was out a fair bit, used the utilities in PHD2 and now within 1 arc min of the Pole!

My Polemaster arrives today to finish off the alignment...so excited.

many thanks to all for your help with this.

Paul
Reply With Quote
  #16  
Old 31-07-2019, 02:56 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Polemaster worked a treat...love it! it took nearly 7 minutes to tweak after I first connected to the camera!

Paul
Reply With Quote
  #17  
Old 31-07-2019, 06:29 PM
Nikolas's Avatar
Nikolas (Nik)
Dazed and confused

Nikolas is offline
 
Join Date: May 2012
Location: Melbourne
Posts: 1,201
Quote:
Originally Posted by peeb61 View Post
Polemaster worked a treat...love it! it took nearly 7 minutes to tweak after I first connected to the camera!

Paul
it totally transforms the whole experience doesnt it?
Reply With Quote
  #18  
Old 08-08-2019, 05:44 PM
peeb61's Avatar
peeb61 (Paul)
Always looking up

peeb61 is offline
 
Join Date: Jan 2007
Location: Wollongong
Posts: 678
Quote:
Originally Posted by Nikolas View Post
it totally transforms the whole experience doesnt it?
Yes Nikolas it certainly does...just love it.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 08:15 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Meade Australia
Advertisement
Lunatico Astronomical
Advertisement
OzScopes Authorised Dealer
Advertisement
SkyWatcher Australia
Advertisement
Bintel
Advertisement
Celestron Australia
Advertisement
Astronomy and Electronics Centre
Advertisement