Advice on obey wall height please

[Max N]

I currently have a fixed pier with a small decking platform around it. Recently I was caught out by an unexpected rain shower, just as I was ready to start imaging, so I had to get all the equipment back indoors in a hurry. Of course the skies then cleared, but I didn't have the heart to get everything out and set up again.

So I'm now thinking that I would like to convert this to an 'observatory', but nothing grand. Just the minimum necessary so I can leave everything set up between sessions. Floor, four walls and a ROR. Maybe a rain sensor and an automated system to park the scope and close the roof - or at least an alarm so I can manually close the roof.

I can't decide how high to make the walls, so I'm looking for some advice. In particular, is there any disadvantage to a low roof height which would necessitate parking the scope in a horizontal position before closing the roof? Or (to ask the same thing another way) is there any advantage to being able to leave the scope pointing at the sky between sessions?

If I went the automated route, could I rely on the scope/mount parking itself before the roof closed, or would that be asking for trouble?

I'm using a Celestron AVX mount. I can't really afford to upgrade the mount at the moment, and I don't know how easy it would be to remote/automate the AVX or how reliable it would be.

Any thoughts/advice gratefully received :-)

[tooth_dr]

My walls are 5ft high as I felt it kept the pier and scope at a useable height and also gives me good view of the lower targets without having to build a wall that partially drops or folds down.  Downside - can’t stand up inside when roof is closed. 

[Adam J]

Wall height will depend on the lateral size of the obsy as that will govern minimum angle. So how big do you want to make the base is the first question. 

Personally I would advise you to build an obsy where your nominal scope is free to move to any position with the roof closed. 

[tooth_dr]

1 minute ago, Adam J said:

Wall height will depend on the lateral size of the obsy as that will govern minimum angle. So how big do you want to make the base is the first question. 

Personally I would advise you to build an obsy where your nominal scope is free to move to any position with the roof closed. 

Can you close your roof with your scope pouring up in any position? I think this would be excellent but only figured it would work with a dome. I can only close my roof with my scopes parked horizontally, regardless of it being my ED80 or 250px. 

[swag72]

My observatory wall is about 5 foot high I would say... It means that the scope needs to be parked horizontally and that I can't stand up in it when the roof is closed. This has been fine until recently when I got a longer scope....... I want to look at possible automation and so in case things go wrong and the scope doesn't park when the roof closes you need to make sure that the scope at it's highest point is beneath the wall height. For me, this means I need my walls now at 2.10m. Imagine if your roof closed before the scope had parked (for whatever reason) and the roof damaged the scope....... The other good thing about a high roof is that if it's not automated and it begins to rain you can just haul the roof across and worry about the scope later. 

[mikeDnight]

32 minutes ago, Max N said:

I currently have a fixed pier with a small decking platform around it. Recently I was caught out by an unexpected rain shower, just as I was ready to start imaging, so I had to get all the equipment back indoors in a hurry. Of course the skies then cleared, but I didn't have the heart to get everything out and set up again.

So I'm now thinking that I would like to convert this to an 'observatory', but nothing grand. Just the minimum necessary so I can leave everything set up between sessions. Floor, four walls and a ROR. Maybe a rain sensor and an automated system to park the scope and close the roof - or at least an alarm so I can manually close the roof.

I can't decide how high to make the walls, so I'm looking for some advice. In particular, is there any disadvantage to a low roof height which would necessitate parking the scope in a horizontal position before closing the roof? Or (to ask the same thing another way) is there any advantage to being able to leave the scope pointing at the sky between sessions?

If I went the automated route, could I rely on the scope/mount parking itself before the roof closed, or would that be asking for trouble?

I'm using a Celestron AVX mount. I can't really afford to upgrade the mount at the moment, and I don't know how easy it would be to remote/automate the AVX or how reliable it would be.

Any thoughts/advice gratefully received :-)

Wall height should also protect you from winds as well as stray light, so even if it means giving up some horizon, the added protection will pay dividends especially on nights with a winter breeze. It also aids with dark adaption if the walls are shielding you and your scope from local lighting.

Attached are some pics of my 8' by 7' ROR. 

 

Sorry but this is currently the only external view I can find. 

[Davey-T]

You can park the scope horizontally and then unpark it with no loss of accuracy so shouldn't be a problem.

How much room have you got ? as obviously the further out the walls are the lower you imageable horizon will be, work out your horizon and work backwards from there.

I have 6 foot high walls but also a telescopic pier that raises the scope another 12".

Automating is a whole nother can of worms best done after you can achieve a reliable hand operated system.

Dave

[Adam J]

20 minutes ago, tooth_dr said:

Can you close your roof with your scope pouring up in any position? I think this would be excellent but only figured it would work with a dome. I can only close my roof with my scopes parked horizontally, regardless of it being my ED80 or 250px. 

Yes, by design with scopes up to a 6 inch Newtonian I am able to close the roof with the scope in any position. See my obsy build thread. 

I use a hatch at the end of the pent roof to allow the roof to clear the scope. In cant see lower then 20 degrees above the horizon but in any case houses block lower so there is no point in making the obsy walls any lower. 

 

[Max N]

26 minutes ago, tooth_dr said:

My walls are 5ft high as I felt it kept the pier and scope at a useable height and also gives me good view of the lower targets without having to build a wall that partially drops or folds down.  Downside - can’t stand up inside when roof is closed. 

I think I'm OK with not being able to stand up inside with the roof closed. Do you open and close manually?

[Max N]

28 minutes ago, Adam J said:

Wall height will depend on the lateral size of the obsy as that will govern minimum angle. So how big do you want to make the base is the first question. 

Personally I would advise you to build an obsy where your nominal scope is free to move to any position with the roof closed. 

The decking is roughly 2.4m x 2.4m, about 8' x 8'.

[Max N]

26 minutes ago, swag72 said:

My observatory wall is about 5 foot high I would say... It means that the scope needs to be parked horizontally and that I can't stand up in it when the roof is closed. This has been fine until recently when I got a longer scope....... I want to look at possible automation and so in case things go wrong and the scope doesn't park when the roof closes you need to make sure that the scope at it's highest point is beneath the wall height. For me, this means I need my walls now at 2.10m. Imagine if your roof closed before the scope had parked (for whatever reason) and the roof damaged the scope....... The other good thing about a high roof is that if it's not automated and it begins to rain you can just haul the roof across and worry about the scope later. 

I hear what you're saying, thanks. So basically I need to decide whether I want to automate, or at least allow for automation in the future.....

[swag72]

Just now, Max N said:

I hear what you're saying, thanks. So basically I need to decide whether I want to automate, or at least allow for automation in the future.....

I would say so yes...... I didn't allow for automation and neither did I allow for future upgrades of scopes!!

[Adam J]

My obsy is small only 6x6 foot so you would most likely get away with 6 foot high walls with the 8x8 obsy. Just also depends on your current pier height. It's not a great idea to image very close to the horizon anyway. 

[Max N]

20 minutes ago, mikeDnight said:

Wall height should also protect you from winds as well as stray light, so even if it means giving up some horizon, the added protection will pay dividends especially on nights with a winter breeze. It also aids with dark adaption if the walls are shielding you and your scope from local lighting.

Attached are some pics of my 8' by 7' ROR. 

 

OK, so there are some intrinsic advantages to higher walls, apart from just clearing the scope in any position. I do have a little local light pollution so this is something to factor in, thanks

[Davey-T]

Mines 6' X 6' with 6' walls and pent roof.

Dave

8 X 6 would give you space for a warm room.

Another thought if you use standard size 2400 X 1200 sheets and design around it avoids unnecessary cutting

[Max N]

20 minutes ago, Davey-T said:

You can park the scope horizontally and then unpark it with no loss of accuracy so shouldn't be a problem.

How much room have you got ? as obviously the further out the walls are the lower you imageable horizon will be, work out your horizon and work backwards from there.

I have 6 foot high walls but also a telescopic pier that raises the scope another 12".

Automating is a whole nother can of worms best done after you can achieve a reliable hand operated system.

Dave

I'm in a bit of a valley, so I can't image at really low angles anyway. Plus imaging higher up seems to give better results where I am, so I usually go for higher targets....

My current thinking is about 2.4m x 2.4m....

I'll try and measure what angle the surrounding hills etc restrict me to, that might answer my question for me!

[Max N]

20 minutes ago, Adam J said:

Yes, by design with scopes up to a 6 inch Newtonian I am able to close the roof with the scope in any position. See my obsy build thread. 

I use a hatch at the end of the pent roof to allow the roof to clear the scope. In cant see lower then 20 degrees above the horizon but in any case houses block lower so there is no point in making the obsy walls any lower. 

 

 

Thanks Adam, I'll have a read of your thread

[Max N]

Just realised that predictive text has changed obsy to obey in the topic title......

[Davey-T]

14 minutes ago, Max N said:

Just realised that predictive text has changed obsy to obey in the topic title......

It doesn't like in-park either (un-park) 

Dave

[tooth_dr]

1 hour ago, Max N said:

I think I'm OK with not being able to stand up inside with the roof closed. Do you open and close manually?

Yes it a very simple design, but with no chance of automation of the roof. It’s a 12x8 shed with 4 foot partitioned off for a small room with pc in it.  I can see down to the visible horizon but to be honest imaging is pretty hopeless at that level. Plus wind gets too but the roof slides off north so I do get some protection. But when I’m in the shed because the walls are 5 foot I can feel like I’m just outside and not confined by a shed which is a nice feeling. 

[laser_jock99]

If you have decent, viewable horizons then it is worth putting some thought into how you might set the pier height or otherwise contruct the obsy to view the horizon adequately.

My obsy walls are over 6 feet high- yet by having a tall pier and parking the scope in a particular way it is possible for me to image almost down to the horizon.

Scope parked horizontally down, with counterweight bar retracted.

 

Scope is able to peer over the obsy wall horizontally.

[ollypenrice]

I host five robotic instruments and we have a very clear 'house rule.' The roof must be able to close with any of the scopes in any position. If you don't follow this rule it is an effective certainty that there will be a collision sooner or later. I was talking to Marc Breton about this (he runs a vast hosting operation near me with very expensive hardware and sophisticated IT) and he has exactly the same rule. He said, 'If the roof can collide it will happen.'

What we don't see all that often is the simple solution to the propblem, which is to make the roof higher but have the upper sides rolling off with it. So when open you have nice low walls. Some examples:

The drop down flap is entirely automatic and simply follows the opening of the roof. All dead simple. (I only do simple here!)

You can also make a roof like this roll back over a warm room:

Olly

[Max N]

Thanks Olly, food for thought.

Like all simple ideas, it is simple when someone shows you.....

I do want to leave the automation route open, so I will follow your advice and eliminate any chance of collision. I think realistically, the only targets I might want to image that are low would be planets. I need to do some research to figure out which directions would benefit from fold-down walls, and which (if any) I don't need to worry about

Cheers

[ollypenrice]

On 3/11/2018 at 17:20, Max N said:

Thanks Olly, food for thought.

Like all simple ideas, it is simple when someone shows you.....

I do want to leave the automation route open, so I will follow your advice and eliminate any chance of collision. I think realistically, the only targets I might want to image that are low would be planets. I need to do some research to figure out which directions would benefit from fold-down walls, and which (if any) I don't need to worry about

Cheers

The general rule would be to have the roof roll off to the north if possible. It will probably impede the low view unless it rolls off a long way, but what is low in the N sky will, in its season, end up topside of Polaris and plenty high enough.

Olly

[Max N]

Thanks Olly, I think I can arrange it that way. Once I have made progress with some plans I will start a thread.