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Saturday 28th 30-33F, frosty overnight but now with a heavy overcast. The serial grey skies continue.
I spent some time clipping the string of red diodes to the inner edge of the dome's base ring. The string [green twin flex] used to be laid loosely on the top of the base ring but always looked untidy. The solar panel control box/battery unit had almost run out of juice through cold and lack of sunlight.
The diodes provide too little light to spoil my night vision. They only help to show the limit of the floor space. Or rather the inner edge of the dome's base ring. Which can approach the limit of seriously overhanging telescopes. Usually the binoviewers cause the problem. I can't get my head behind them at certain object heights.
After that I went round tightening every screw and nut on the mounting. It seemed to help the overall stiffness when the telescopes were manually pushed back and forth. Having opened the shutters to let some light in they wouldn't close again. They were dragging at the top for the very first time since I built the dome.
Standing on a crate didn't help. I still couldn't get high enough to use the shutter's own inertia. So I had to drag a stepladder up the steep ladder to the observatory floor. The heavy duty, drawer slides at top and bottom are fully covered by the shutter "boxes." So it may just have been local icing. Pushing the shutters closed at half height solved the unusual friction problem.
The shutters have been remarkably easy to close until today. Usually I just gave them enough of a tug to get each whole shutter moving as one unit despite their inherent flexibility. Then they would close tightly together without the least gap between the inner ribs. There is, of course, an overlapping weather strip of ply to shed the rain from where the inner shutter ribs come together. Initially, I had planned to have cords over pulleys to pull the shutters closed together at the top. It was never worth the effort to fit them until now.
I made the shutters slightly too wide to ensure they would meet. So there is an air gap between their outer ribs and the fixed ribs on the edge of the dome's observation slit. This provides some air movement when the dome is closed in hot weather. Despite letting in some light the gaps have never leaked even in driving rain with a gale behind it.
The ability to open and close the dome in mere seconds is a major advantage of domes. It allows much greater freedom to use the telescopes in changeable weather. Many amateur astronomers have to carry everything outside and set up from scratch every time they want to observe or image. The mounting usually has to be re-aligned to ensure accurate tracking. With a permanent observatory none of this is necessary. When the choice is between going out in the cold, or watching TV, the observatory will win every time over the open lawn.
Being sheltered from the local breeze will depend on wind direction and where the dome [observation slit] is pointed in the sky. Fortunately my site enjoys SW winds while I am usually pointing the telescopes at the sun in the SE all morning. Much the same orientations exist after dark with the moon and planets. There is a wall of tees to the west. This helps to dull the wind but robs me of seeing objects in the western sky.
Only after lunch, with the meridian flip on the sun, will it sometimes become breezy in the dome. I even have a better way of coping with cold, breezy conditions. I add a tubular, fleece, "polo neck" to my usual, winter outfit. It makes a huge difference not to have the wind whistling around one's neck. Though I usually wear collared jumpers under my down jacket and wear a trapper hat, these do not offer the same protection as my simple, fleece neck "sleeve." Highly recommended if you can find one.
Skiing salopettes are very useful to avoid cold legs and feet if you are sitting for long periods in the observatory. These insulated over-trousers can usually be found for small change in many charity shops. My latest winter observatory wear is a pair of fake-fur lined, "snow" boots. Bought cheaply online and good for -50C! I haven't had cold feet since I've tried them. My feet slide effortlessly in and out of the boots thanks to the glossy fur lining. Far easier to don and remove than my usual walking boots.
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