Equipment review : Building a new observatory
New Observatory : from conception to finish
Foreword :
During the building of my new of my new observatory, Raßberg II, I took almost a thousand photos. The most important stages of the building work can be viewed under the gallery section of this website at Raßberg II
I must admit, that for our “first attempt” it worked brilliantly. It protected all the equipment through the Styrian seasons – cold winters and hot summers and was generally quite up to the task. The reason for the demolition – Maria, the farmer’s second daughter had a baby in the autumn of 2012 and planned to move back onto the farm at Christmas. Therefore we had to extend my house and unfortunately ( or fortunately, depending on how you look at it ), the extension was exactly where the observatory was.
When I realized I would need to rebuild, we considered many, many options. The first one was a tower in the garden with a dome observatory with direct access from my living room – really cool. However, this would have been extremely expensive and probably a waste of money, due to severe problems from thermal currents from the very large terrace and roof areas. We then considered various other options and locations – nearly everyone who had experience, recommended as far away from buildings as possible, which then gave us one prime location, the chicken shed !
After a lot of thought, we realized that the first observatory really wasn’t bad, but with our experience could be bettered. So what would be different ? Well, firstly, the size – the old one was definitely too small. At 2.5m x 2.5m one couldn’t swing a cat in it. When working alone, it was just possible, but one had too carry out some acrobatics to move around without bumping into delicate equipment. When I had guests, it was a nightmare, I’d often say “come on in, put your backs against the wall and don’t move ! “ The new observatory is be 4m x 3,8m – luxury. We will also bury all cabling under the floors, making movement easier. The old observatory was a DIY garden shed, just modified. Well, the new one will use the same modifications ie an internal skeleton to carry the roof, and we will simply clad the outside using larch ( very weather resistant and fits in with all the other things we have built on the farm – raised flowerbeds and a playhouse / adventure area ). Luckily we have a young lad helping who is a trained carpenter and he has lots of ideas. We used a wind and weatherproof lining on the inner walls plus isolation. We also clad the interior and painted this matt blue to reduce reflections ( a tip from a friend, black looks depressing in daylight and dark blue looks black at night ). The roof was so constructed, that thermal heating would be reduced. The roof design was also optimized so as to provide more protection from the elements. The carpenter also suggested an improved roller system for the roof – this was our biggest problem on the original design. Additionally, I want to pinch an idea from Arnold’s brother who has an energy efficient house – we will lay ducting underground and draw in cool air in order to minimize overheating in the summer.
The new location is, as mentioned above, next to the chicken house. We have already felled the two walnut trees there, which would have blocked the views. The old building provides electricity nearby and also stands directly between the observatory and farm house ie will shield the observatory from stray light. We have surveyed the site and with the exception of a very small area in the east, it has unhindered views in all other directions. As if all this isn’t good enough, despite being some 50m from my house, the site appears to have a good WLAN connection to my office.
As often the case, I had an idea, made a sketch of what I wanted and then got started. However, as is often the case here on the farm, after countless beers and discussions, things got changed here a bit and there a bit and in the end, something completely different emerged.
Firstly, the new location, although for astronomy was great, was not so good for building. We ended up removing almost 200 tons for earth to reach a good base for the foundations. Originally we planned a “simple” 4,0 x 3,2 m shed, standing on a point foundation. First change in plan – we decided to make the shed 4,0 x 3,8 m but have it standing on a plinth 11m x 4m. The idea was to have the area in front of the door like a patio. As a result, we dug a strip foundation to a depth of 50cm and width 40cm, and this for the entire 11m x 4m plinth. The pillar to support the telescope was another matter altogether. Here we dug a 2m deep hole that was 1,5m square and filled this with concrete and steel. Next we built a foundation wall along the strip of concrete to bring us back up to ground level, finishing this off with a concrete mantel to make sure it was level. We also raised the pillar foundation to the same height with concrete blocks. It was important that the central pillar and all its foundations be completely separated from the main foundation, so as to avoid vibrations. We then cemented a 3m long 20cm stainless steel tube in place, this would be the final pillar.
After laying drainage all around the building and an air circulation tube ( more of this later ), we filled in the central part of the foundation with rubble. A nice touch was laying the old pillar from my first observatory to rest next to the new pillar ! The foundation was finished off by laying power cables, a metal reinforcement grid and finally 15cm of concrete. We were now back to ground level – and it didn’t look too spectacular, despite more than 40 tons of concrete, 5 pallets of blocks and nearly 150 tons of rubble. It looked like a big concrete pad !
Next up was the building itself. Well, once again the beer set in and we had some more ideas. Originally the roof would slide to one side on wooden beams and end up over the patio area. Arnold then had a great idea. We would close in this area and make an annex building ! This would have to have a flat roof, so that the other roof could slide over it. On the other building site ( the extension to my house ), we had removed a number of windows and patio doors. We decided to recycle these and turn the annex into a conservatory.
Before beginning, the first job was laying a damp course. The frame for the building went up fairly quickly, in a couple of days, but because all this was being carried out as an aside project, in real terms it took a few weeks. Then came the tricky bit, the roof. On my first observatory, the rollers for the roof were the most difficult part. This project would be even more demanding. The wooden structure alone weighed nearly 1500kg, then there were over 1000 roof tiles and we had to allow for snow. We planned a weight of over 5 tons – this would need serious rollers. Our friend Freddie, who has an engineering company obtained some special industrial rollers which are usually found on aircraft hanger doors – these should do the trick !
Once the skeleton structure was finished, the exterior walls were covered with a type of goretex seal and then larch cladding. We chose larch as it is very weather resistant and nearly everything else we have built on the farm is in larch, so the new building would fit in well.
On my original plan, the walls were to be 1,80 -2,00 m high. Well, unfortunately that plan went right out the window. We had to set the annex’s flat roof high enough to allow the door to the chicken house to be opened. Then we had to allow room for the entire roller system. This pushed the interior wall height up to almost 2,80m. When I saw this, it was apparent that a) the 3m long pillar seemed to be getting shorter day by day and b) I would probably need a lift to get up to the telescope, which would be another 60 – 100 cm higher ! Well, I then had the idea of a raised floor, yet another plan change. The raised floor was supported on a grid like structure and had 3 steps from the main doorway to get up to floor level. From here the real height was just less than 2m, similar to my first observatory.
The foundation to the central pillar was raised further, but somewhat narrower - a 60 x 60cm block which came through the floor and finished about 50cm higher than the floor. The idea here was to use the flat area as a base for all of the power sockets, so no cables would be on the floor. The cable tree from the telescope ( with power and USB connections for various cameras, filterwheels, fans etc. ) would only go to this raised area avoiding the mass of cables I used to have on the floor. The USB cables plug into a hub which in turn runs under the floor to the laptop.
The interior walls were then clad with plasterboard and all the screw holes and gaps filled with plaster. The roof was then painted white ( to allow some lighting during the daytime ) and the walls and central plinth were painted in matt dark blue to avoid reflections. Originally I had intended painting everything in matt black but a fellow astrophotographer recommended blue, during the daytime this is far friendlier and at night works just as well as black. During the building I noticed that the light coloured pine floorboards quickly became shabby and were difficult to clean. I ended up buying and fitting the cheapest possible laminate flooring. This gave a dark, smooth finish which was easily wiped clean. Finally we finished the annex room in a similar fashion, with plasterboard walling, finished in a cream colour.
During the final stages, I started to install all the instruments and electrics. There was the telescope and its air cooling system, the main camera and a guide camera, the motorized filterwheel and a laser pointing system to aid alignment. Everything seemed to work fine, the first improvement I noticed was the freedom of movement and the lack of miles of cables all over the place.
During the final stages, whilst testing everything, a number of unforeseen problems arose and had to be addressed. The majority of these problems were due to the construction of the rail system for the roof. For those interested in this, I will briefly describe the problems and our solutions, but if anybody needs further information, then just email me for details.
Problem 1 : the roof was very difficult to open and close. We quickly decided that long term we needed a motor, as the roof was high up and very heavy. However, this was not the only problem. The roller block was situated in the middle between fully open and fully closed. We noticed that in both the open and closed positions, the extreme weight caused the rails to sag, making movement difficult. Initially we planned on additional rollers underthe rail, at both ends. We had one inside the observatory that ran along the wooden beam and a second one externally that would run along the flat roof of the annex. The builders fitted a stainless steel recess for this to run in. When I saw this, my first thought was, what happens in winter when the recess fills with water and freezes ? Well, just a few days later, we saw what happens, 2cm of rock hard ice ! Secondly, we noticed that the roller inside, although working, moved with difficulty – the shear weight of the roof was pushing the hard roller into the soft wood and causing indentations. So, what did we do ? On the interior roller we placed a 3mm galvanized steel sheet over the wood, this worked well. The exterior roller was a big problem. We decided the only solution was to extend the rail system and install a second roller block to take the weight. This was a) very expensive and b) meant knocking holes in the adjoining building to allow the rails to move. However, the rail system meant that water and ice were no problem ie could be used all year round. We did this and this too worked. At the time we also installed a motor, which initially was operated by a makeshift system.
Problem 2 : We thought everything would now be ok, but we were wrong. We had only opened and closed the roof a few times, when we noticed that the entire roof was going askew. It had moved almost 4cm sideways. We noticed this because the carpenter had built everything so perfectly, that bits started catching and knocking out lumps of plasterboard or damaging paneling. We determined that the problem was having the motor drive only on one side. The motor was powerful and pushed and pulled with ease. The otherside just dragged and hence things went askew. We decided to fit guide rollers to the motorized side, to stop roof from moving sideways. This modification also seems to work.
Problem 3 : whilst positioning the roof for the above modification, all of a sudden the roof just stopped although the motor was still running. After a lot of searching, we discovered that the toothed ratchet in the rail system was damaged. This had a nylon spacer which was screwed on, and all the screws had been ripped out by the power of the motor. We decided that a new ratchet had to be installed and that the spacer had to be metal and welded in place. This modification was a nightmare, as the entire rail system was enclosed and had almost no access. None the less, we managed it and since then things seem to be running fine.
In the meantime, I have fitted a proper controller with end switches, which makes use much easier and safer.
Lessons learned : our next observatory will certainly have the drive system placed centrally, this will resolve many issues. I also believe we could have manufactured a good solid rail system, which would be easier to maintain, simply from angle iron. Also in hindsight, I would opt for a flat roof – construction would be easier and cheaper, obstruction of view less, and it would be lighter.
Having said all this, the finished observatory really is superb, there are certainly very few of this standard around. I have begun working in it and it really does match my expectations. It is solid, easy to use and offers lots of space. This is important, as I am slowly getting a reputation as being an astronomer in the region and many people ask to visit the observatory. This was almost impossible in the old one, now it is not only possible, but very practical.
