DBO2

With the move to the new house, construction started on the new Observatory in May 2011.

With a complete blank sheet of paper, I settled on the following design.

  • Roll off roof.
  • Warm room for computers and a human.
  • 3.6mtr x 2.7 mtr floor plan.
  • All wood construction to reduce costs and allow the ability to repair any part at a later date.
  • Bitumen corrugated roof.
  • Low 1.5mtr high sides to allow full view at low elevations.
  • Observatory oriented roughly North /South, with roof rolling off to the North.
  • Close to the house for security and access
  • Full 360 degree all sky access.
  • Observatory raised off ground to prevent rot
  • 1 sq Mtr concrete block for scope pier mounting.

With all that worked out, I calculated the structure needed to s.it on six 40mm square concrete pillars, which are sunk 600mm into the ground. The 125mm x 50mm framework formed the base of the observatory and these sat on the six piers, which are raised above ground level.

In the centre of the 2.4 mtr x 2.7 mtr observing area, I dug a hole sufficient to take a 1sq meter concrete block which would give the telescope pier a very stable and vibration free platform. This block stopped just below the observatory.

Once done, I was ready to start of the framework. This consisted of six 75mm x 75mm uprights – four at the corners and two at the point between the cold and warm sections. Additional 50mm x 50mm uprights filled in the open areas to allow sufficient fixing points for the clapboard outer sheathing.

The roof runs on inverted trolley wheels attached to a base framework. The wheels run within ‘U’ section steel channel, bolted to 100mm x 50mm bearers running each side and along the length of the structure.

Once the framework was complete PVC plastic sheeting was stapled to the outside of the framework and then covered with 155mm x 19mm tanalised clapboard. Rather than nail these to the framework, everything was fixed using galvanised woods crews. This allows for easy removal of any component should repair be necessary.

The roof was constructed in a similar manner using the same 50mm x 50mm framework. Three sides of the roof protruded below the outer edges of the observatory allowing a leak free seal. The Southern end which has to roll over the observatory base retained its watertight integrity with a 5mm clearance and a fixed outer board fixed to the observatory base and covering the gap. When closed, even in driving horizontal rain, the roof join never leaks. The sizes of the roof were covered in clapboard, and the roof was sheathed in a bitumen corrugated sheets, with a generous overlap coming downs the side to retain water tight integrity. The roof ended up a lot heavier than I had hoped and was only just possible to open it without assistance 🙁

The floor was constructed using 150mm x 25mm decking wood, which was screwed to the base framework. The inside of both the warm and cold rooms was lined with WBP 9mm plywood sheet. While this was done purely for cosmetic reasons, these sheets added considerable strength to the structure, which is rock solid.

The pier from the old DBO was was reused, but I cut it down to about 1.2 metres high – a height which allows the scope to just peer over the top of three of the observatory sides.

A warm room was constructed at the door end of the observatory. The partition between the cold and warm sections was constructed using a 50mm x50mm framework, which was then covered in 9mm plywood. A sheet of toughened glass was installed in the partition to allow sight of the scope area while remaining inside the warm warm. A door in the partition allowed access to the cold side. as well as allowing heat in the warm side to be retained.

The desk from the DBO 1 was reused but I did install a second monitor, keyboard, and mouse in the cold area, to allow control of the scope from there.

The observatory was completed in September.

 

Then disaster.

 

In December of 2011, the roof took flight in extremely high winds, end to end rolled downwind before leaping a 3 metre high hedge before landing again . Miraculously the scope was untouched when the roof took off. Apart from a couple of hours a light drizzle of rain, suffered no damage whatsoever.

With the weather being so poor and the need to redesign a much lighter and less aerodynamic roof, I decided to completely clear the observatory of equipment and remove the warm room. Over the next couple of months various roof designs were made and rejected. In the end I decided that reducing weight and reducing internal height would allow a 30% weight saving. I was able to salvage most of the old roof and incorporate 95% of the components in the new design.

To stop the roof going airborne again, I decided to use two 5000kg breaking strain lorry straps, which lock roof to the observatory base. Despite the horrendous winds over the Autumn and Winter of 2012, the roof has remained in place and has proved to be completely leak free. The weight saving excercise now means it’s a doddle to open up on my own. The reduced height inside isn’t a problem either and it’s still possible for me to stand inside without my head hitting the roof

With the warm room gone- which in retrospect, hasn’t really been a great loss, I designed a box to hold the computer and provide storage for the camera, eyepieces and other kit I need in the observatory. I call this the Pulpit for obvious reasons.

Constructed with 9mm ply over a 25xx square framework, the pulpit contains the PC CPU, the Losmandy’s power supply and a case worth of eyepieces and cameras. To keep everything damp free inside, a 60 watt bar heater keeps the electronics nice and dry and free of mould.

The lid opens up revealing the PC screen, the keyboard and mouse and is at a height that I can stand at the keyboard. While sitting down sounds nice, in fact I found the chair always got in the way, so I find standing allows a lot more freedom to move around from the PC to the scope when needed.

The work was completed in April 2012 and despite a poor Summer, I’ve managed to make inroads into observations of my Messier Objects List as well as do quite a bit of Solar work too.

All in all the lighter roof has made it significantly easier and without the warm room has made the whole observatory feel much roomier. This proved to be useful during my astronomy group’s annual BBQ held here, we managed to squeeze in a dozen or so bodies keen to look through the scope.

Preparing the site Pouring six concrete support piers
Laying out the observatory support floor framework The hole for the pier mounting block
Casting the pier block The basic framework
PVC plastic lining sheet Clapboard outer planking
Roof structure underway…. …and ready for ends and sides.
Roof completed Internal roof structure
Desk and lining for the warm room Warm room partition and window going in.
Scope in and almost ready for first light Solar imaging

Then Disaster

With no warm room, the end gable had to be lowered and a 250mm removed from the old door. Old roof runners salvaged from the old roof were reused.
Roof framework under construction. Roof framework completed and ready for installation of corrugated roof sheets.
Ready for lining interior in the now absent warm room section Exterior construction complete
One of the two sets of roof retaining straps. With the scope parked in this position, the roof rolls off with a few inches clearance. Construction complete. The straps can be used to tie down the roof when it’s open just in case of any gusts while observing.
Ready for the first clear night. Ready for the first clear night.
The Pulpit undergoing testing before installation. All fired up and ready to go.