Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Welcome to Stargazers Lounge

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customise your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.


DIY rotating Nissen Hut or Pulsar 2.7m?

11 posts in this topic

Hi Guys

New member, ancient ATMer.

I have joined to directly access Pulsar dome owners' fund of information.

I am building a raised platform 8' off the ground to provide a much bigger sky.

Trees and hedges surround and interrupt our dark rural property.

Our modest 1.5 story home is on the southern border of our large garden.

Fortunately neighbours with security lights at a hundred yards south and SW are safely hidden by the house.

Increasing age demands shelter from the almost constant wind.

My two main OTAs are now much too heavy for easy lifting:

I am using a chain hoist and nested stepladders!

I have a 10" f/8 reflector with premium optics and a 7" f/12 R35 iStar refractor. [Presently folded.] Both ATM builds.

My almost completed, massive DIY GEM has 2" shafts and lots of heavy aluminium. ie. Immovable!

It is running AWR IH2/ASCOM drives to 11" and 8" Beacon hill wormwheels.

The images show my mounting on a temporary test stand.


Now the real reason for my unscheduled interruption: [Much as I like talking about myself.] ;)

I am torn between a DIY all aluminium, rotating "dome" of the cylindrical roof variety or buying a Pulsar 2.7m. dome only kit.

Making a hemispherical dome is a long term exercise in geometrical and sealing frustration IMHO.

The off-the-shelf Pulsar 2.7 is rather cramped for my 2 meter long Newtonian even when the dome is mounted on a much larger "box".

Does any recent Pulsar 2.7m dome purchaser have the minimum internal dimensions between opposing quadrant ribs?

I understand the 2.7m is actually 2.6 from Pulsar's own drawings but that may be external.

With so little clearance available I really need an accurate figure.

Thank you for your patience if you have reached this far.





2 people like this

Share this post

Link to post
Share on other sites

I have built several domes and half cylinder "Nissen" style observatories. The latter type are cetainly easier to make and cost less in materials. I have a 8.5" F12 refractor in one and a 16" SCT in another, they have worked well for several years. The main construction is in aluminium and all bearings are stainless, the guide rails for the bi-parting sliding doors run on stainless steel tubing. Pictures on the front page of the Astronomy Centre website.  :icon_biggrin:

3 people like this

Share this post

Link to post
Share on other sites
4 hours ago, Peter Drew said:

I have built several domes and half cylinder "Nissen" style observatories. The latter type are cetainly easier to make and cost less in materials. I have a 8.5" F12 refractor in one and a 16" SCT in another, they have worked well for several years. The main construction is in aluminium and all bearings are stainless, the guide rails for the bi-parting sliding doors run on stainless steel tubing. Pictures on the front page of the Astronomy Centre website.  :icon_biggrin:

Hello, Peter,

Your reputation precedes you. :icon_biggrin:

Are there lots of detailed images online of the barrel roofed observatories? I wouldn't want to put you to the trouble of posting loads of images.

My feeling is that an up-and-over shutter is better in my breezy situation. The semi-cylindrical roof readily lends itself to such an arrangement.

The shutter can also be partially lowered. While the bi-parting shutters must be always wide enough not to stop down the telescope.

Share this post

Link to post
Share on other sites

There are more pictures on the website. The half cylinders are in four parts, the two outers are fixed and the two inners are the sliding doors. The sliding doors have housings each containing groups of three small bearings which in total form the effect of linear bearings when sliding on the guide tubing, I found this arrangement easier to operate and more robust against the strong winds that we experience. The sliding doors only pass over the zenith so that the telescope can be used overhead unobstructed, the rest of the cylinder is covered.  

I also have built a few folded 8" refractors, your design looks very interesting as does your fine equatorial mount.  :icon_salut:

1 person likes this

Share this post

Link to post
Share on other sites

Hi Peter

Praise indeed, from the Master himself.  :blush:

Thank you for the further details of the half cylinder observatories.

My own reading of online opinion on bi-parting shutters is that they acted like sails.

Particularly in comparison with the more "flush" and symmetrical up and over design.

Since your observatories are sited on an open moor I must bow to your direct, hands-on knowledge and long experience. 

I am steadily working my way though your website images to find closer views.

The pure half cylinder has the advantage of requiring very simple edge framing which could be DIY rolled from aluminium angle profile.

Required size and thickness of profile still an unknown.

With 2.5m x 1.25m x 1mm aluminium costing well over £100 [local equivalent] per sheet I have hesitated in getting cracking.

I can make a half cylinder 3m wide out of six full sheets including the up-and-over shutter. [My own personal choice.]

3m would give me "breathing room" for a stacked folded refractor/reflector in the the same black alloy framing.

But, is 1mm sheet sufficiently stiff once curved into a self supporting, half cylinder?

I'm trying to completely avoid any plywood since the weight rises so dramatically.

I would be working entirely alone, as usual, and must avoid heavy lifts at my age. [70]

The Pulsar 2.7 sounds as if the components could just be managed, working alone, in still air.

The problem with the 2.7 is likely to be the lack of clearance for so large, an asymmetrically mounted [GEM] OTA.

I am discussing the idea [with myself] on my blog:  These rough drawings are not strictly to scale.



barrel cylinder dome txt.jpg

dual ota txt 2.jpg

Edited by Rusted
oversized images

Share this post

Link to post
Share on other sites

Hello again "Rusted".

Without wishing to sway your design preferences, at this preliminary stage all things are open to consideration.

I think bi-parting doors become wind sails only when applied to domes and not cylinders. My doors fit exactly over the fixed parts when fully open so do not increase the footprint or the profile of the observatory. I have made up and over doors for domes but they have added problems to overcome. These are essentially the weight which has to be lifted in either direction from the zenith and having to have a separate drop down front section so that door can be passed over the zenith without its upper edge fouling the building at the rear. Waterproofing is another consideration.

Don't let age get in the way, I built my largest cylinder observatory single handed when I was at least 70!   :icon_biggrin:

1 person likes this

Share this post

Link to post
Share on other sites

Hello Peter and thanks for continued patience with a fellow "retiree." :wink:

You are quite right, of course, that a cylindrical form will not notice the change in outline of a bi-parting shutter as would a hemisphere.


Abrupt change of direction: I am now looking at fiberglass, dome-shaped, calf rearing igloos.

At least three different but similar models available in Europe. Holm&Haue, and Eurosilos Igloo16.

Plus others in heat reflecting white or absorbent green. Expected life at least 20 years.

4.5m in diameter x 2.2m high. That's 14'6" in old money. They come in three GRP segments with a half circle open doorway.

I can mount my refractor and reflector together inside a 14'+ dome and still have change from half-a-crown. :hello2:

Closing the open doorway with reinforced plywood panel gives me a surface to fit a low access door and the beginnings of a slit.

Making a slit to the zenith will weaken the central segment but I can easily stiffen the structure on the inside.

The usual laminated plywood and rubber wheels for rotation, of course.

Any thoughts on this continuing lunacy? :icon_biggrin:


holm laue igloo 3 rsz 500.jpg

holm laue igloo assembly 2 rsz 500.jpg

holm laue igloo assembly 1 rsz 500.jpg

Share this post

Link to post
Share on other sites

An interesting concept, if the price is right it might well be worth a try. Many years ago I made a 8 metre dome converting a steel silo dome, the dome was straightforward enough but cutting a slit into it and making good for the door was a nightmare, glass fibre should be a lot more manageable.  :icon_biggrin:

1 person likes this

Share this post

Link to post
Share on other sites

Hi again,

I'm getting more quotes from competing calf dome, manufacturer's agents today.

If I go ahead I should probably start a new build thread for the amusement of the assembled masses.

I have now ditched my original, square, 8' raised platform idea and will build a cylindrical support wall 8' high to provide a guarded 'veranda.'

This will provide a much larger, stabilizing footprint and "free" scaffolding to work from in much greater safety than ladders.

The cylindrical room below the dome floor will be accessed from a 'proper' door leading to safe, internal steps to a drop-down trapdoor.

I'm thinking of using pyramidal, adjustable, concrete, carport anchors for footings for the multiple support posts.

The ground of the intended dome site is soft garden soil which is two feet lower than the rest of the area.

After providing a compacted gravel bed for the anchors the area around these will be back-filled with more compacted sand & gravel.

This will save a lot of digging holes, mixing and laying heavy, wet concrete around deeply buried posts and will simultaneously match the site's ground level.  :thumbsup:

Share this post

Link to post
Share on other sites

Sorry, Guys.

I have just discovered the 4.4m calf dome weighs 485lbs!

Which makes each of the three segments 160lbs.

I think this is far too much for one elderly person to manhandle.

Particularly since there is so much modification to carry out.

Then lifting it onto a platform 8' off the ground!

It might be possible to hire a machine for the lift, but it's still a lot of very heavy work.

So it's back to the Porsa 2.7. Or an aluminium, half cylinder.

For those interested I was looking at  between £2500 and £3000 for the calf dome, delivered.

No doubt your local prices are quite similar if you are interested in such a project.



Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By badgerchap
      Hi all,
      I'm considering building a small scale observatory - remote imaging to keep the form factor small. The problem is I only rent my house, so I can't exactly go all out. My landlord is fairly forgiving though, so I can do minor damage as long as it's repairable when we eventually have to move.
      My plan then is to repurpose a steel frame (40mm tubing) which I will clad and insulate. This will be easy enough both to build and to move/remove if necessary. However, I'm not sure what I should do about the mount.
      My setup isn't massive - TS Optics 6" f4 reflector on an NEQ6 with a WO 66mm refractor guide scope. However, I'd like something more stable than the NEQ6's standard tripod as I'd like to not have to do PA every time I go out. I'm looking for ideas for a pier that will be sturdy enough, yet that I don't have to immerse in concrete. I've no worries about burying the base of it just in the ground, but I'm not sure if that'll be stable enough. My thoughts were to use some 160mm HDPE pipe, bury it to a depth of about a metre and fill with sand. The bottom end would be capped so the sand doesn't run out and the top end would be plugged with (something as yet undecided) to hold a pier plate.
      How stable to people think this would be? As I'd be operating remotely, I'm not worried about disturbing it whilst imaging, but I am concerned it might shift with temperature changes etc.
      Is this a rubbish plan? If so, any ideas about an alternative?

    • By Barrilles
      I thought I would share this design.   I needed a house for the 6 inch Mak Cas on a pier.  I wanted it bug proof and I wanted a sitting area near the scope that I could warm.  Some wind block would be nice.  After reviewing a lot of roll off roof designs I went with a roll off building instead. It rolls to the west, where trees would otherwise block the sky.  I am clear to the south, and the house blocks a bit to the north.  The 5 by 10 building was built to roll on 6 casters on top of square steel tracks. There is a 3 by 5 warm room in the back. The floor is steel for rigidity, while the building is normal 2x construction with hardie exterior to match the house.  Its a bit heavy to push by hand, so we added a bicycle crank set to move it along. The bicycle frame is inside, with a very narrow slot in the floor for the chain.  I have yet to install the electrical as winter came and slowed down construction.  So far, no rodents, wasps, bats or other guests have been able to move in. Enjoy.

    • By CSM
      I have my Celestron 9.25 AVX permanently mounted in my observatory.  So having done my alignment I simply hibernate the scope when I finish and restart the next time with minimum fuss.  What advantages would I gain by using the Celestron SkyPortal with my Android phone?  I mainly do imaging.
    • By Gib007
      Read more and download:
      Tweet Remote Control is a Windows program written in Visual C# 2015, embedding the Tweetinvi and ASCOM references. It is meant to act as an inconspicuous safety backup, particularly useful to those with remote hosting for their astrophotography equipment.
      The original motivation behind Tweet Remote Control is for when you lose remote control of the remote computer. This can happen due to various reasons, including TeamViewer failing or their server encountering connectivity problems. It is sometimes necessary to restart the computer, or TeamViewer alone, for example, in order to recover remote control. When all else fails, parking your mount and closing your roof may become necessary measures to protect the equipment against possible collisions and from the elements. It is here that Tweet Remote Control can assist, provided the remote computer has an active Internet connection, of course. This stops you needing to have someone to immediately attend to the equipment physically.
      Put simply, Tweet Remote Control starts with Windows and runs in the background. It connects to a Twitter account of choice and therefore responds to specific commands, effectively sent by tweeting them via the connected Twitter account. The program monitors this connected Twitter account and reads new tweets made. If a tweet made matches a command written into the program, it deletes the tweet, executes the command received and tweets on your behalf (to update you on what is happening). Since all the program requires to function is a connection to a Twitter account, it need only be running on the remote computer with an active Internet connection - the rest is up to your tweet commands! Many features are supported, including control of ASCOM roofs, mounts and power relay switches (as well as Lunatico Astronomia's Seletek Dragonfly).
      Tweet Remote Control ensures it always starts automatically with Windows (once you connect a Twitter account, that is), and re-authenticates with Twitter automatically every two minutes. This ensures the program is always active with minimum delay, even if the remote computer's Internet connection drops for a period of time. When Tweet Remote Control starts, if it is connected to a Twitter account, it does so minimised to your Windows system tray as a small, black and white icon labelled TRC. Here, the program will remain with no user input required and with no pop-ups whatsoever. The key is being always-on and always-ready without user input and without hassling the user with pop-ups or messages.
      Finally, Tweet Remote Control is 100% free. Please feel free to contact me for bug reports or to request new features be added!
      Current list of capabilities in version 1.4:
      1. Restart your computer
      2. Shut down your computer
      3. Restart TeamViewer on your computer
      4. Close an ASCOM roof
      5. Open an ASCOM roof
      6. Check the current status on an ASCOM roof
      7. Park an ASCOM mount
      8. Check the current status on an ASCOM mount
      9. Open power relays (turn off) on a Dragonfly
      10. Close power relays (turn on) on a Dragonfly
      11. Check power relays on a Dragonfly
      12. Open power relays (turn off) on an ASCOM power relay switch
      13. Close power relays (turn on) on an ASCOM power relay switch
      14. Check power relays on an ASCOM power relay switch
    • By RayD
      Well the time has come, along with the all important permission, for the start of my very own observatory build.  I've looked at lots of builds on SGL, many of which I'm really impressed with, but obviously each build has its own constraints in relation to time, money, size of garden and of course now permitted development rules.  With this all taken in to account I decided on the following as a general concept:
      Overall size to be 3.6m x 2.4m (12' x 8' in old money) I have decided to have a warm room, even though I do image mostly remotely, as I thought I could store equipment in there, and it could house the power supply etc.  Also it's a place to go when I've been told off for doing something wrong, as you do!  Main scope room to be 2.3m x 2.4m and warm room 1.2m x 2.4m. I will be using a roll off roof, custom design but really nothing new, and this is likely to be pent as I have limited space for it to open.  Being pent makes it easier to open only a section of it (I think). Main base frame is beam and block using 7n MD concrete blocks sat on hardcore, topped with 150 x 50 pressure treated joists. I am using 75 x 50 for all the general framing as I want to use 50mm Celotex insulation with a reasonable air gap. I will be using a steel pier on a 1m3 plug. I think that's about the general overview, and I have drawn it all up in CAD and Sketchup for a 3D perspective (SWMBO doesn't get CAD drawings).
      I know the build is going to take some time, and I'm aiming to be imaging in there by the Spring of 2017 being realistic, with total completion in the Summer.  I will try to get it done earlier but don't want to compromise quality for speed, and of course work gets in the way, with only weekends currently available for working on it.
      I'll update this thread as much as I can and please feel free to throw and comments or recommendations my way as I will be explaining why I am doing what I'm doing in each post, but as it's my first observatory build I would welcome any and all comments, good or bad.
      Let the build begin