Dome Control Help

[KyleStoke]

Hello Everybody

Im in dire need of help trying to sync my dome and telescope using POTH, everything I seem to do makes it worse.

In the below picture I have added in some lines and letters to try to make sure I am measuring the correct things

A = Dome Equator

B = Radius of the Dome = 39.11 inches

C = Dome center to scope pivot point, i believe i have no off set here so have left as 0

D = Dome center to mount pivot point, I have this at -1.8 inches as slightly to the south of center

E = Hight of mount above equator, although on the picture this looks above it is below by - 1 inch

F = Mount pivot to optical axis, this I have a 6.5 inches.

I hope you can see on this picture where i have being trying to measure.

 

I have then inputted the same values into the corresponding two dome control interfaces.

The corrasponding letters are hard to see but the values are the same

If these values are correct any other ideas what i have done wrong im very much at a head against a brick wall stage.

Many Thanks

Kyle

[PhotoGav]

Hello Kyle,

I don't use POTH, so can't be certain, but I have just been through the process of getting a dome to sync with a telescope (through SGP) and found that things were not perfect with the measured values. The one value that seems to make the geometry work out and position the slit correctly for the telescope is your value 'F', the 'Distance from mount pivot point to telescope optical axis' and I think the 'GEM Axis Offset' value in POTH. I see that the value in POTH is negative - is that correct?

Anyway, I found that altering that value moved the dome slightly and I kept trying new values until things aligned satisfactorily. In the end it was almost double the actual value for my 8" scope and just a little more than the original value for my Star71.

Good luck!

[steppenwolf]

I use POTH to control both my mount and Dome and all works very well. You only enter the figures into POTH, not into any other interface.

This diagram may help you:-

[KyleStoke]

1 hour ago, PhotoGav said:

Hello Kyle,

I don't use POTH, so can't be certain, but I have just been through the process of getting a dome to sync with a telescope (through SGP) and found that things were not perfect with the measured values. The one value that seems to make the geometry work out and position the slit correctly for the telescope is your value 'F', the 'Distance from mount pivot point to telescope optical axis' and I think the 'GEM Axis Offset' value in POTH. I see that the value in POTH is negative - is that correct?

Anyway, I found that altering that value moved the dome slightly and I kept trying new values until things aligned satisfactorily. In the end it was almost double the actual value for my 8" scope and just a little more than the original value for my Star71.

Good luck!

Hi PhotoGav,

I am planning on using SGP also ones i get all this fine tuned, I will have a go changing the Gem offset the negative value is probably incorrect.

 

30 minutes ago, steppenwolf said:

I use POTH to control both my mount and Dome and all works very well. You only enter the figures into POTH, not into any other interface.

This diagram may help you:-

Hi again Steve do you not also use the Ascom Dome controller?

Thanks for the chart it does look useful

[steppenwolf]

Quote

Hi again Steve do you not also use the Ascom Dome controller?

Not directly - POTH calls the dome's ASCOM driver but you don't enter any figures into that, only in POTH.

You have PM

[PhotoGav]

SGP is well worth the investment of both money and time. The integration and automation it offers is excellent.

Good luck sorting the sync issues - I look forward to reading that it all works very soon! At least this is something that can be done in daylight. 

[KyleStoke]

Cheers Gav,

With much help from Steve I believe it is well on the way to being fixed, I will post an update to confirm.

In regards to SGP I used the trial version before I had the dome and liked it. I will get the full version when im all set up and ready to go.

[PhotoGav]

23 minutes ago, KyleStoke said:

With much help from Steve I believe it is well on the way to being fixed, I will post an update to confirm.

The Scope Doctor is a complete hero, it's true!

[KyleStoke]

I'am happy to report that all seems to be working well.

I managed to get out for an hour last night before it clouded over to confirm my scope was pointing at the NCP.

It was, I had remeasured everything and have much more accurate data in the system. 

The main issue as Steve discovered for me was that the dome had not been calibrated and I had managed to knock that out even more.

Basically all that I have done today is offset where the dome originally thought 0° was to compensate for where the scope was pointing, with limited testing the scope ends up dead center of the shutter.

All that remains now is some longer test runs and some proper clear dark nights.

Many Thanks to all.

[steppenwolf]

That's great news, Kyle - let the real fun begin!

[alcol620]

Hi everyone. I'm very near to getting a Pulsar observatory with the Rigel Rotational Drive Unit.

Reading the above thread, does this mean that by using POTH there is no need for an expensive software package to automate the syncing of the dome to the scope? I currently use APT software to control the camera, scope, filter wheel etc.

Thanks for feedback

[PhotoGav]

26 minutes ago, alcol620 said:

Hi everyone. I'm very near to getting a Pulsar observatory with the Rigel Rotational Drive Unit.

Reading the above thread, does this mean that by using POTH there is no need for an expensive software package to automate the syncing of the dome to the scope? I currently use APT software to control the camera, scope, filter wheel etc.

Thanks for feedback

I would whole heartedly recommend SGP as a brilliant conductor of the dome imaging orchestra. It isn't expensive, in fact, for what it does, its down right cheap! It's far more stable than APT and far more powerful. Seriously consider moving to it.

As for answering your question... I don't know, as I don't need to know, because SGP works and will make the whole imaging process with an automated Pulsar Dome almost easy (I'm afraid 'easy' just isn't in the astrophotography vocabulary!!).

Good luck and don't wait to buy the dome, just do it - best thing I ever did!

[steppenwolf]

POTH will indeed carry out all the calculations required to align the dome aperture with the telescope and it is included free with the ASCOM platform. Opening the aperture and closing the aperture are also controllable from the POTH dialogue box.

However, it is normal for POTH to be used with other software like SG Pro (as mentioned above) or CCD Commander + MaxIm DL for a more autonomous system but it doesn't have to be this way and POTH works fine on its own if you are happy to carry out other functions of an imaging session manually.

I have found POTH to be very stable when used with the Pulsar driver.

[alcol620]

28 minutes ago, steppenwolf said:

POTH will indeed carry out all the calculations required to align the dome aperture with the telescope and it is included free with the ASCOM platform. Opening the aperture and closing the aperture are also controllable from the POTH dialogue box.

However, it is normal for POTH to be used with other software like SG Pro (as mentioned above) or CCD Commander + MaxIm DL for a more autonomous system but it doesn't have to be this way and POTH works fine on its own if you are happy to carry out other functions of an imaging session manually.

I have found POTH to be very stable when used with the Pulsar driver.

Thanks Steve, Presumably with POTH controlling the dome, I can continue with my software of choice, APT, to automate everything else? I understand that dome control may be a feature of a future version of APT.

[alcol620]

41 minutes ago, PhotoGav said:

I would whole heartedly recommend SGP as a brilliant conductor of the dome imaging orchestra. It isn't expensive, in fact, for what it does, its down right cheap! It's far more stable than APT and far more powerful. Seriously consider moving to it.

As for answering your question... I don't know, as I don't need to know, because SGP works and will make the whole imaging process with an automated Pulsar Dome almost easy (I'm afraid 'easy' just isn't in the astrophotography vocabulary!!).

Good luck and don't wait to buy the dome, just do it - best thing I ever did!

Gav thanks for feedback. APT has worked fine for me for a couple of years and having got the hang of it I am reluctant to change. I accept that SGP could be more powerful but I am content with APT for the moment. Totally agree with your comment on "easy".

Regards

alec

[steppenwolf]

27 minutes ago, alcol620 said:

Thanks Steve, Presumably with POTH controlling the dome, I can continue with my software of choice, APT, to automate everything else? I understand that dome control may be a feature of a future version of APT.

That's pretty much the case but for it to work, both the dome and the mount must be controlled via POTH so instructions to move the telescope must be ASCOM derived via POTH.

[PhotoGav]

10 hours ago, alcol620 said:

Gav thanks for feedback. APT has worked fine for me for a couple of years and having got the hang of it I am reluctant to change. I accept that SGP could be more powerful but I am content with APT for the moment. Totally agree with your comment on "easy".

Regards

alec

Alec, I quite understand! I was an avid APT user before getting my dome and rate the software highly. I was in exactly the same position as you when about to hit the buy button on the Pulsar, wanting a system that would control the dome in sync with the mount. SGP was the most cost effective solution. I switched and found the learning curve remarkably low gradient, the help files and forum make it relatively simple. I don't know how many extra features APT has introduced since I last used it, but SGP has things like auto meridian flip, cloud watcher integration, in sequence auto focus and full sequence automation, which are all essential if you are trying to create an automated dome system.

Good luck with your dome, whichever software you go forwards with. One thing is certain, SGL and especially Steve (@steppenwolf) are the best help resource available! I look forward to following your progress. 

[alcol620]

13 hours ago, steppenwolf said:

That's pretty much the case but for it to work, both the dome and the mount must be controlled via POTH so instructions to move the telescope must be ASCOM derived via POTH.

Thanks Steve, much appreciated. Over 12 months ago I seemed to remember that I had to connect something using POTH, sounds stupid but I am not sure what it was now. I will have to check this out, the mount may already be using POTH!! My memory isn't what it used to be. Is there an easy way to check if POTH is being used? IT isn't my top subject.

Thanks again for you help.

Alec

[alcol620]

2 hours ago, PhotoGav said:

Alec, I quite understand! I was an avid APT user before getting my dome and rate the software highly. I was in exactly the same position as you when about to hit the buy button on the Pulsar, wanting a system that would control the dome in sync with the mount. SGP was the most cost effective solution. I switched and found the learning curve remarkably low gradient, the help files and forum make it relatively simple. I don't know how many extra features APT has introduced since I last used it, but SGP has things like auto meridian flip, cloud watcher integration, in sequence auto focus and full sequence automation, which are all essential if you are trying to create an automated dome system.

Good luck with your dome, whichever software you go forwards with. One thing is certain, SGL and especially Steve (@steppenwolf) are the best help resource available! I look forward to following your progress. 

Gav

Many thanks for feedback, encouragement and best wishes

Regards

Alec

[steppenwolf]

32 minutes ago, alcol620 said:

I will have to check this out, the mount may already be using POTH!! My memory isn't what it used to be. Is there an easy way to check if POTH is being used? IT isn't my top subject.

Hi Alec,

Assuming that previously you have controlled your AZ EQ6 GT using EQASCOM (EQMod) then the easy way to check is to call up whatever software you use to control your mount and check what the software says is the connection method - normally there is a Tab headed 'Telescope' and you connect your 'telescope' there. If the connection says something like EQMod ASCOM HEQ5/6 then you are connecting directly to your mount but if it says POTH then you know that you are indeed using POTH. If POTH is shown as your connection then you can click on 'select' and that will tell you what POTH is subsequently connected to - most likely EQMod ASCOM HEQ5/6. POTH just works as a 'hub' which can be very useful in its own right but it does also include the dome 'slaving' feature discussed here.

I hope that helps!

[alcol620]

Thanks Steve, that is great I will check it out. Not sure what we would do without the likes of your goodself.

Take care

Alec

PS I might be back!!

[steppenwolf]

2 minutes ago, alcol620 said:

PS I might be back!!

Ask away Alec, there are plenty of knowledgeable people on here to help!

[alcol620]

Hi Steve

Me again. A quick question. When you had your Pulsar Dome installed, did you have the pier offset to the south or was fixed it in the center of the dome? I read somewhere that there needs to be a small amount of offset to cater for the EQ mount.

Thanks again

Alec

[KyleStoke]

Hi Alec

I use SGP and have also used APT in the past the change between the two is not to radical, and once use to SGP it pretty much does everything.

I did not bother with an offset to the south my understanding was that it was only required if you are using a very large scope.

[alcol620]

Thanks Kyle, very helpful

Regards

Alec