Dome build: Ever onwards!

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Friday: Fitted U-shaped metal handles on the inside of the veranda doors to give me something to pull on. It was proving difficult to close the doors when it was windy. 

Then  I removed the upper covers on the shutter doors and sealed between the upper and lower covers. After which I screwed all along the edges of both shutters to ensure they remained firmly in place. It sounds easy until you have to do it at full stretch from a tall ladder. I used a combination of inside and outside ladders. 

My safety belt was clipped onto the ladders in case I tried to fly. Which I nearly did today while I was fitting the door handles. I was crouched against the open trapdoor when I shifted my weight and automatically grabbed the [vertical] hatch for balance. Fortunately the two sliding bolts held the hatch firmly, with a bang against the stepladder handrails. Otherwise I could have been hurled headfirst and backwards down the ladder!

I also tidied up inside the observatory and swept the upstairs floor. Small off-cuts of wood and plywood had been gathering dust along with odd, fallen screws and packing nails around the edges of the floor. 

I hung up a digital, inside/outside thermometer with an outdoor sensor on a lead. This will be useful to monitor temperatures within the dome. The inside reading will be compared with the remote sensor hanging free under the floor of the northern veranda where sunshine never falls. 

An overheated dome can cause warm air flow out of the observation slit leading to poor seeing. Domes, in general, have a poor reputation for this thermal agitation problem. Like looking over a garden bonfire at its worst.

A white finished dome helps reduce inside temperatures by reflecting solar warming. However, my plan is paint the dome a rather dark green to make it all but invisible against the background trees. How that colour heats up, in warm sunshine, on a plywood base is anyone's guess. Plywood has poor thermal conductance and low heat capacity. 

The dome is exceptionally well ventilated around the skirt unless I deliberately close the gaps. Opening the downstairs entrance doors may force a thermal "chimney effect" up through the open pier. This should quickly scour any warm air out of the dome. Any breeze from the southerly direction will accelerate heat loss. Quite a gale blows up through the pier when wind conditions are suitable. Opening the veranda doors on the westward side will help further.

The dome is primarily to allow the telescope[s] to be permanently set up on the mounting without the need for constant re-alignment. The dome provides a weather canopy without much increased warmth. It also reduces thermal radiation to the cold night sky. So the observer remains slightly warmer and more comfortable without the normal wind chill of being fully exposed.  The slightest breeze drags body heat out of the observer and chills their extremities. Hopefully the dome will also end the problem of dewing of the optics.

I also need a clock which can be easily read in the dark without needing to find a torch. A wrist watch is a nuisance at night. Particularly when wearing a down jacket with elasticated cuffs and similar gloves.

The AWR Goto handset [paddle] provides an illuminated, digital reading of the time. Though I would need reading glasses to be able to make any sense of the figures. The same goes for the Goto controlling laptop of course. I only need +1 diopter at normal range to read screen text and to see the cursor on a planetarium star map. 

A string of red diodes on a long strip will hopefully be fixed around the dome. These would provide only a gentle wash of light to avoid crashing into things in the dark. The heavy counterweight on a GEN is always a head magnet. Red light will help to avoid spoiling my night vision.

A "downstairs" light will be vital to remind me to close the trapdoor to avoid falling through the hole in the observatory floor. I had planned a micro-switch on the hatch but that would risk failure to light up when the hatch is open and still lethally dangerous. A fixed downstairs light will provide the safety warning without any risk of unnoticed malfunction.

The big stepladder was deliberately placed inside the building despite all the obvious "pitfalls." An outside ladder would soon accumulate ice and snow. Which would be even more dangerous than man traps! Provided I clean my feet of snow before I climb, the ridged, aluminium treads should provide safety and adhesion. So now I need a doormat inside the building.I still haven't decided how to cover the ground floor. Slabs seem obvious while the present pea gravel shifts about a bit in foot trafficked areas.

I am sorely tempted to go and buy the green, dome paint tomorrow. The risk of being caught in midwinter without the ability to paint for many months ahead is a bit of a worry. If I don't paint the dome then I risk the wooden dome structure becoming saturated. With no chance to dry out until a warm, spring day arrives much later. The problem is finding a suitable weather window to ensure the paint goes onto a completely dry base.

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