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THE OBSERVATORY

                                                 

                                               afgewerkt


The first thing I had to decide was the shape and the archirectural style of my observatory. I took every possibility into consideration, knowing that it must be easy to build with as little money as possible. There is absolutely no discussion, that a dome is the most ideal observatory. But that was no option for me, because I find it too expensive and also very difficult to build. A roll-off roof was a possibility but then I needed a bigger part of my vegetable garden and I could not live with that. An additional disadvantage of a roll-off roof is the fact that one is always very exposed to cold wind and moisture. And that's even worse for computers and camera's. So finally I decided to build an ordinary wooden shack, 2.5 meters square, with a saddle roof. At the north side the roof cannot open, but at the south side the roof opens in two parts, and slides downwards. Under protection of the northern part of the roof there is a bench who supports the computers. There is no possibility to observe the northern hemisphere. But that is no problem, cause there is mostly not very much to see, except perhaps a lost comet now and then. Polaris is just within reach, and that's good enough for me. Polaris is necessary to point the scope at the pole. And sooner or later all the northern objects come into reach.
My first job was to draw up a plan. I used AutoCad, so I could see if the hinged roof would work properly. On the basis of this plan I purchased all the wood for the shack, and from then I could start the construction.
First I had to put impregnated poles (7cm x 7cm) in the ground, embedded in concrete. This concrete is a mixture of 5 parts coarse sand and 1 part cement. It is mixed and used dry. The moisture in the ground makes sure it hardens well.

                                                      palen

The best way to work, is first to drill holes in the ground with a ground-drill. You can make perfectly round holes with it, as deep as you want, and not too wide. that saves concrete and is more stable and solid afterwards. Ground-drills can often be rented for a day or more in most DIY shops.
Around the poles I made a rim with 1meter long
concrete boardstones.

                                                boordstenen

On this boardstones I nailed lead plate (2mm thick) against the wooden poles. The lead is sold in rolls of several widths, and is normally used by plumbers. As you can see in the picture, i bended the lead in a S-shaped form.

                                                deklood

Next thing to do was to install the walls. The walls are made of curved and impregnated planks. The lower plank comes over the lead board. The planks fit tongued and grooved into eachother. Important!! Make sure to nail the planks with the tongues upward and the grooves downward. Otherwise rainwater will find its way in. The planks must also be level.

                                                 ruwbouw

The roof is made of 3 seperate waterproof plywood plates. The surface of these plates is covered with a thin and shiny layer of hardboard. These plates are mostly used to make framework for concrete constructions. The fix northern roof is covered with roofing shingles. Roofing shingles are heavy, so I decided to cover the hinged roof with fluid rubbercoating because I did'nt wanted to overload the hinges. But now after a couple of years the coating is totally worn out, so I think to use shingles too.

At both sides of the walls I mouted a U-shaped profile. In this profiles the roof parts slide up and down by means of a metal tap.

                               rails         
dak          

To give the observatory a certain presence, I motorized the roof. To do this I used an old (but still good) garagedoor motor. I found one on a scrapyard. A couple of axles and pulleys, and lots of imagination were needed also, but the roof works as it should be.

                               motor         katrol

The electric control is made with a few relays, end-switches and a start and stop button in a small metal housing. Nothing special. A switch takes care about the turning direction of the motor. Open or Close.
Now it was time to take care about the inside. I heavily tamped down the ground with a sledge hammer, until it was 5 to 10cm lower, and very hard. On top of the ground came two layers of plastic foil (0.5mm thick), against rising moisture. And where the telescope had to come, i drilled holes 50cm deep on the 4 coins and then i poored an armed concrete square plate on it, with a tickness of 10cm, and 1.2 meter square.
On top of this plate came 16 concrete tiles (30cm square). Now I had a perfect level and steady floor.

                               betonplaat          tegels

An observatory must have some electricity facilties. And now it was the right time to fix this. Fortunately next to the observatory I have a greenhouse who is provided with electricity. Therefore  it was easy to lay an underground cable to the shack. I provided my observatory with 8 outlets. But after a few months I found that this was too little. So folks don't hesitate to install a few outlets more. Better too many then too little. And a 230 volt multiple socketblock is very cheap.
Around the tiles I made a floor in OSB plates. The floor rests on a supporting construction in bangkirai wood. Bangkirai is very strong and doesn't rot. The floor feels warm in wintertime, and that counts during a nightlong observing session in freezing temperatures.

The inside walls of my 'kingdom' are covered with 10mm thick CDX plates. These plates are much cheaper then waterproof plywood, and good enough for this purpose. 

To prevent my computers from moisture I made a case in 10mm plywood. At the inside I glued polystyreen plates (3cm) for isolation.
In wintertime the front of the case is closed with an isolated cover, and the case is kept at 10°C with an electrical element and a temperature controller.
You can see the element on the left side of the computerscreen.

                                isolbak          isolbak1
 
Even from the first night I used the observatory, I realized what a great comfort it gave to observe. You sit in front of the pc, while the camera is gathering photons. You almost don't feel any wind, and the apparatus stays dry. When the session is over, you shut the power off, close the roof, and that's it.
In the old days, at this point, there was still half an hour work, moving scopes and computers inside.
About my observatory I have only one thing to say :"Oh boy what a luxury" !




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