My 2.2m dome arrived today

[tooth_dr]

25 minutes ago, Laurin Dave said:

Hi Adam does it maintain sync to the south after a meridian flip ...   And is the north issue the same both sides of the mount?  This might give you a clue as to what’s going on ..  the parameters I played with to get mine to sync were GEM offset and the Home Angle ..  to set my Home angle I set GEM offset to zero and pointed the scope to the Meridian ..  my thinking being that the middle of the shutter should then line up with the RA axis 

HTH

Dave

Thank you Dave. With regards to either side of the meridian - I just did a slew to Eps Vir and then to Alp Boo (either side’s of meridian) and for both positions the telescope and slit opening were lined up such that I could image through both scopes unobstructed.

[tooth_dr]

@Laurin Dave

I did a few movements around north and have sketched them crudely below.

Due north - slit aligned well

NW - slit moves too far west

NE - slit moves too far east

 

I’m sure for a smart person this would be easy to work out 😂

 

[MarsG76]

That is very awesome.. a permanent setup is a very comfortable way do do a lot more astronomy....

 

[Laurin Dave]

Hmmm, tricky... I’d suspect the North South and GEM offsets from what you say .. although I’d check them and your other measurements before changing anything 

Dave

[Jkulin]

7 hours ago, tooth_dr said:

When I now choose a target in CdC both dome and scope move together and it’s quite disorientating when in the dome and looking up!  But it’s working

I know what you mean Adam, I had difficulty working out where the dome was pointing.

I'm using the Arduino Dome software which communicates using the Ascom, and one of the things I noticed that by default there was a 60second delay, yet you mentioned that the dome slew with the mount, it might be worth making that setting and see if it gives it time to settle, I've dropped mine to 20s, but as yet have not tried it with an OTA on.

[tooth_dr]

6 hours ago, Jkulin said:

I know what you mean Adam, I had difficulty working out where the dome was pointing.

I'm using the Arduino Dome software which communicates using the Ascom, and one of the things I noticed that by default there was a 60second delay, yet you mentioned that the dome slew with the mount, it might be worth making that setting and see if it gives it time to settle, I've dropped mine to 20s, but as yet have not tried it with an OTA on.

Hi John

Thanks for the reply.  My understanding is that when the scope is set to point to x degrees az, the dome goes to x plus offset degrees az, offset based on my measurements. 
 

I have been following your thread, but not sure what benefit the delay is?  Unless the dome measurement is based on the final resting position of the mount?

Im going to recheck the measurements today and see if they are right. 

 

Best wishes

Adam. 

[Jkulin]

1 hour ago, tooth_dr said:

Hi John

Thanks for the reply.  My understanding is that when the scope is set to point to x degrees az, the dome goes to x plus offset degrees az, offset based on my measurements. 
 

I have been following your thread, but not sure what benefit the delay is?  Unless the dome measurement is based on the final resting position of the mount?

Im going to recheck the measurements today and see if they are right. 

 

Best wishes

Adam. 

You maybe be right Adam, I am not sure, but it maybe worth a try.

It threw me the lag to start with, but there must be some thinking behind it.

[Rusted]

Off at a complete tangent, as usual, but how difficult would it be to widen the slit and fit bi-parting shutters?
You could flog kits to owners of Pulsar domes.

Two, curved strips of ply will provide the stiffening on either side of the wider slit.
Cut the dome back for the extra slit width and zenith reach and then glass and resin over the ply to seal.
Split the up-and-over shutter down the middle and apply drawer slides at top and bottom.
Add a wider weather strip to one shutter to seal them when closed and overlapped.
Job done!

Shall I get my coat?

[tooth_dr]

Still having no luck with the dome slaving. 
 

Last night I faffed about for two hours. @Xsubmariner sent me his input figures for slaving which I’m going to try tonight but they look similar to mine.

Pointing west if I change offset to 800mm I can see through dome.  Pointing east I have to set it to 0mm.  I have gem offset measured at 410mm.

Any suggestions welcome. 

Edited August 3, 2020 by tooth_dr

[inFINNity Deck]

Hi Adam,

I have a domed observatory with a side-by-side set-up myself. Common issues are the following:

- measurements taken using the wrong reference (centre base of mount vs. intersection RA/DEC axis): Some software (like MountWizzard) knows the offset to the intersection of the RA/DEC axis for a number of mounts and require the centre of the base from which the RA/DEC intersection is calculated.

- dome radius vs. diameter: some software use the former, other the latter. Some ask for the latter, but actually need the former (e.g. SGP).

- accuracy set too wide: some drivers like LesveDome allow to set the accuracy with which the dome should be slewed. If this is set too high, the dome may not slew correct. Setting it too low, may cause the dome to jitter between positions.

- Lateral offset of imaging scope: as far as I know only MountWizzard can handle the lateral offset for an imaging scope, all others assume the scope to be mounted at the centre of the mount. I have recently written an article for these calculations, which I hope will be published this month or next month in https://astronomytechnologytoday.com

Nicolàs

[tooth_dr]

3 minutes ago, inFINNity Deck said:

Hi Adam,

I have a domed observatory with a side-by-side set-up myself. Common issues are the following:

- measurements taken using the wrong reference (centre base of mount vs. intersection RA/DEC axis): Some software (like MountWizzard) knows the offset to the intersection of the RA/DEC axis for a number of mounts and require the centre of the base from which the RA/DEC intersection is calculated.

- dome radius vs. diameter: some software use the former, other the latter. Some ask for the latter, but actually need the former (e.g. SGP).

- accuracy set too wide: some drivers like LesveDome allow to set the accuracy with which the dome should be slewed. If this is set too high, the dome may not slew correct. Setting it too low, may cause the dome to jitter between positions.

- Lateral offset of imaging scope: as far as I know only MountWizzard can handle the lateral offset for an imaging scope, all others assume the scope to be mounted at the centre of the mount. I have recently written an article for these calculations, which I hope will be published this month or next month in https://astronomytechnologytoday.com

Nicolàs

Very useful, thank you!  SGP comment is interesting.  What I was thinking was that if my parameters are correct, then it should line up the centre of the mount everyone, but it doesn’t do that all.  I got a single 20 min sub last night and the mount and dome weren’t aligned any more. 

[Laurin Dave]

HI Adam ... maybe the Home Angle is out..   to check this set the GEM offset to zero and point the scope at a star on the Meridian .. sync the dome and the middle of the shutter should then be in line with the polar axis..  

Dave

[Anne S]

On 06/07/2020 at 18:39, tooth_dr said:

 

 

 

 

How have you attached your MHP to the dovetail? Mine uses velcro at the moment but I'd like to switch to a more solid attachment method.

Anne

[tooth_dr]

42 minutes ago, Anne S said:

How have you attached your MHP to the dovetail? Mine uses velcro at the moment but I'd like to switch to a more solid attachment method.

Anne

Hi Anne. I just made a piece of aluminium to fit, attached that to the top of the rings of the scope, and used Velcro.

 

 

 

 

[tooth_dr]

@Laurin Dave and @inFINNity Deck

Thanks for the advice.  It was wet last night, so I took at look at this.  Adjusting the GEM offset would not be a proper solution, as it needed to be changed no matter where the scopes were pointing.

I set about changing the EW and NS offset figures last night in POTH, and this gave real time updates on the position.  After half an hour of moving and adjusting, I'm pretty convinced that I have it sussed.  I can point the scope East West South North, in low and high declinations, the dome follows the scope, and all optical hardware is aligned within the slit when the dome stops.

I havent tried tracking the scope for a longer period of time, but it would follow that it should remain correctly aligned, if it stays in the correct position when I moved it to any position as above.

 

My only concern is that the scope had been moved manually during the day and I manually moved it back to its park position before starting my measurements last night.  I am concerned that although the position of the slit relative to the scope is now correct, when the scope is platesolved and it's position corrected properly relative to the sky, then the slit will be slightly out.

Edited August 4, 2020 by tooth_dr

[Jkulin]

Hi Adam,

I had similar thoughts because at the end of the sessions I can't be done with waiting for the dome to rotate back to zero, so I just leave it where it ends up, what I have been doing before commencing the next session if moving the dome manually to the zero position and syncing or telling it to find home which on my setting up is where Steve set the system to look for a peg which tripped a sensor telling it that it was home.

[Anne S]

6 hours ago, tooth_dr said:

Hi Anne. I just made a piece of aluminium to fit, attached that to the top of the rings of the scope, and used Velcro.

 

 

 

 

Just like I do it then except I use an odd Vixen dovetail as I haven't got odd bits of aluminium. It was the edge of your velcro I could see! It looked like the MHP had a plastic foot/spacer. 

[tooth_dr]

Can anyone confirm that my shutter hasn’t been set up correctly?  It stops dead on the zenith but I thought it was meant to go past it? 

(I have an extra strip of aluminium around the circumference but shutter doesn’t fit over it)

 

 

 

 

[steppenwolf]

It is wrong, it should drop below the skirt when open - currently you are limiting your access to the zenith.

[tooth_dr]

25 minutes ago, steppenwolf said:

It is wrong, it should drop below the skirt when open - currently you are limiting your access to the zenith.

Thanks Steve, I had my suspicions that my view was being restricted.  Even that small amount will make a big diference.  Would you be able to post a photo of how low the chain is attached on the shutter, when in the closed position?

[Laurin Dave]

Adam

Have you seen this ? https://www.pulsarastro.com/ekmps/shops/b585dc/resources/Other/drive-installation-guide-feb-16.pdf   .. its shows where the chain is attached

Dave

Edited August 6, 2020 by Laurin Dave

[steppenwolf]

1 hour ago, tooth_dr said:

Would you be able to post a photo of how low the chain is attached on the shutter, when in the closed position?

Here you go - note that this image also shows the correct mounting position for the bottom microswitch actuator.

[tooth_dr]

@Laurin Dave and @steppenwolf

Thank you both. Looks like the shutter door wasn’t fitted exactly to spec by the previous owner.

I can get it repaired later and then work out how to fill up the holes in the skin of the shutter.

[steppenwolf]

You might have to remove the addition to the skirt on the shutter section to ensure that it doesn't snag. To fill the holes, use short stainless steel countersunk bolts inserted from inside and locked with SS washers and nuts.

[tooth_dr]

On 06/08/2020 at 16:10, steppenwolf said:

You might have to remove the addition to the skirt on the shutter section to ensure that it doesn't snag. To fill the holes, use short stainless steel countersunk bolts inserted from inside and locked with SS washers and nuts.

Hi Steve

I did exactly that, and used a dremel to carefully remove the skirt off the shutter section and about 2cm past it either side.  The shutter now operates perfectly, cheers.

 

Unfortunately still having problems and spent two hours last night, finally giving up at 1am, feeling tired and frustrated.  Something isnt quite right with the dome, POTH and SGPro.   I will try to summarise.  I can connect ok to mount and dome to SGPro via POTH.  I have a look on CdC and then slew to my first target using say CdC (also via POTH).  I then take a photo in SGPro and platesolve this, that works fine too.  Then randomly it will say in the notifications in SGPro 'external disconnect of dome detected'.  I can no longer connect to the dome and in POTH it just hangs and I have to shut it down.   I then unplug the dome controller (Shelyak) and reconnect and I can then connect to the dome.  I have to reset the home position using the dome software and resync the home position.  When I reconnect in SGPro, all seems fine, but it doesnt track the scope.

There are 'slave to telescope' check boxes.  If I tick the one in POTH the dome seems to rotate properly, but once connected to SGPro, this box automatically becomes unticked and one in SGPro is ticked (under slave setting for POTH dome).  The dome doesnt rotate though.  However if I tick the POTH slave to telescope it starts to track the mount again, but then it reverts back to being off automatically.

It's hard to summarise this is words, so that doesnt make much sense I'm sure.  But essentially SGPro seems to want to disconnect the dome on occasions, and when it does connect it doesnt track.  100% this is a user input/software error, but it's frustrating as anything.

 

Any help would be appreciated.

I do use the Shelyak dome controller, but it's via POTH so hopefully someone can help me see what I'm doing wrong.