2 - Control room

CCD imaging requires more equipment than visual observing and even "simple" film astrophotography, and much of it isn't designed to be exposed to the damp, nighttime air. While I never had any problems caused by this, I was always worried about it. By the time I had 3 computers and several power supplies in the observatory I was quite concerned and thought I needed somewhere more protected to keep the delicate bits.

Technology had moved on, however, and a control room might not be necessary. Running the CCD remotely (via something like VNC) might be good enough. In the end I decided that I still wanted somewhere dry to keep the computers and that a control room would not be a detrimental step, so I did both - installed a network and added a control room.

Network

I could install the network (even temporarily) and try it out before I built the control room and then decide whether I wanted the control room or not. Installing the network was simple - deciding which network wasn't. In the end I opted for cheapness and simplicity (usually my guiding rules) and installed an old-fashioned coax 10MBPS ethernet. The cable was cheap (cost me nothing for 200 metres) and the network adaptors were $5 each. It requires no hub, no repeaters and is adequately fast.

After some playing with the network cable with it just laying on top of the ground I decided that the network was definitely worthwhile and I should go ahead with that phase without delay. It takes a bit over 4 seconds to transfer a single ST-8 FITS image (3MB) from the observatory to the house computer. Compared to the effort I used to go through this is a breeze, and trivial relative to the 60 seconds to read the CCD out in the first place (I don't have the USB upgrade). I also decided to go ahead with the control room as the extra room it would generate would be desired, as well as keeping the computers out of the weather.

The coax was put into a 20mm conduit (along with a couple of extra multi-core cables to be used for an intercom and possible remote control) and buried. There is about 90-metres of cable between the study in my house and the control room outlet, and another 30-metres between the control room and dome outlet. There's a few metres of cable inside the house and control room and another 10-metres or so inside the dome. A coax network can cope with 176-metres and I'm within that distance and it works fine. Had I opted for 100MBPS CAT5 then it would have been considerably more expensive and difficult (although I'm told that it can be done in a single length of CAT5 between 2 computers only without interference problems).

The network works fine. I can set the system going from the control room then retreat to the house to monitor progress via VNC. Even better, I can then go to the dome and do some real observing while the CCD is busy doing its thing and keep an eye on it from there.

Control Room

The design of the control room was dictated by the initial design of the roll-off roof. Had they been designed as one then it might have been different, but as it turned out (more by luck) the extension looks and acts as if it were intended to be this way.

After much thinking I decided that the control room would be a garden shed just the same as the original skyshed - this would stop it looking too out of place. Careful measurement showed that the extra 25mm gap in the roll-off roof height would be able to just fit over the top of the standard shed roof line with them both having the same floor level.

To complicate matters, the dome was north-east of the skyshed and the (almost invisible) guy-wires bracing the end of the roof rails were a severe hazard to visitors in the dark as they were in a direct line walking to the dome. It would be most sensible to have the control room under the rolled-off section but the height of the walls and other constraints precluded this, so the direction of roll of the roof had to be swapped. This was the first job done.

With an angle-grinder I cut the rails at the door end of the skyshed. I then separated the pieces joining the two sides. Holes were dug for the uprights (including their concrete foundations) and the straight sections, along with their uprights, were picked up and placed in their new holes (on the opposite side so that the rails lines up). This was easier said than done as the concrete footings were not light. But a bit of brute force and ignorance, a wheelbarrow (and my neighbour Rob for one that was too heavy for me) had it done quickly enough. It was then a matter of lining them up carefully, levelling them (which required some extensions added to one side as the ground slopes down that way) and then welding the rails together again. I then cleaned them up and painted them - a job I never got around to doing the first time. Some small shrubs were planted near the guy-wire to make them more noticeable.

The roof now rolled off the other way so I was part way there. Next was to prepare the area for the new shed. It was while doing this that I had a major stroke of luck - I found a shed of exactly the right make for free. All I had to do was to dismantle it and cart it away. My son Alexander and I managed this in a few hours, although things were slowed down a little when it came to the base frame which had been buried in the concrete floor by the inept original owners. The slight damage it sustained while trying to extracate it contributes now to the door not opening quite so smoothly as it should.

The cement was allowed to set for a few weeks, then the shed was erected. It took me the best part of a day with the help of my (sometimes helpful) children. Above-left is a view of the completed shed from the south-west showing how well the new shed blends in with the old. There is a thin, dark line just visible which is the gap between the two. This was subsequently covered over with a section cut from one of the wall panels which wasn't used. You can see the overlap of the roof over the new shed in the next picture (above-centre). The slightly higher roll-off roof is on the left, just overlapping the lower new roof. They blend in perfectly. The covering section is also in place here.

The shed was bolted down in place and the finishing jobs were done. The short gap between the two sheds is sealed on the outside, but there is still a gap on the inside when the roof is rolled back. I cut pieces of thin galvanised steel sheet (remnants of the dome skin) and screwed them between the tops of the sheds to seal this part. Finally, I had to cut a hole in one corner between the two sheds to allow cables to be passed through. This is 100mm diameter (above-right picture) and I pushed a short section of 100mm plastic sewer pipe (unused) through the hole (large enough to take the biggest connector I would expect to use, and then a bit bigger). A rolled-up piece of foam is inserted as a seal once the cables are in place. Mains power was brought through a separate conduit and sockets and lights (both red and white) were wired in place.