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Wednesday 4th: Overnight frost. 43/40F Sunny periods, with fast moving cloud from the west.
My self-built, trapezoid dome in sunlight against a black, northern sky.
The dome is the wrong colour for solar! Green absorbs too much heat compared with bright, titanium white. Though white is [sadly] highly visible from a great distance. The convection currents, produced by the absorbed heat, can spoil the image with thermal shaking and boiling effects.
These heat waves are magnified by the telescope and make imaging difficult to impossible. The effect is not unlike looking over a bonfire. Or admiring a trembling, distant view on a hot day. The dome must be repainted already after only one winter. Will it be more green, or white?
The dome is the wrong colour for solar! Green absorbs too much heat compared with bright, titanium white. Though white is [sadly] highly visible from a great distance. The convection currents, produced by the absorbed heat, can spoil the image with thermal shaking and boiling effects.
These heat waves are magnified by the telescope and make imaging difficult to impossible. The effect is not unlike looking over a bonfire. Or admiring a trembling, distant view on a hot day. The dome must be repainted already after only one winter. Will it be more green, or white?
10:00 Have reset AWR to date and time again. Minus 1 hour to make LST correct. CduC now matches East of Greenwich, just for once.
Changed from lunar set-up to H-a solar stack + D-ERF and three warming bands to combat dew.
10:30 Struggling with dewing again. D-ERF inside and front of objective lens.
Removed heater bands and used hairdrier after removing D-ERF cell.
Dew gone, heater bands back on. Cloud thickening! Proms looking inconsequential.
Removed heater bands and used hairdrier after removing D-ERF cell.
Dew gone, heater bands back on. Cloud thickening! Proms looking inconsequential.
Soft, dim image. Checked through OTA from tail end. Rear of objective heavily dewed!
The only way to clear it is with a door in the OTA behind the objective! Bad weather work.
Wrapped some foam around the objective area with 3 bands heating at 74F.
11:00 5/41F: Managed first capture. The endless cloud insists on crossing the sun! Grr? ðŸ˜
Checked again. Dew reduced to half aperture, circular patch backside of Obj. lens.
11:25 Dew down to 1/3 aperture circle. I shall have to prioritize a foam dewshield. I'll cover the main tube behind the obj. to insulate it and increase its diameter to match the obj. cell. Otherwise there is no suitable surface on which to fit the dewshield. I'm scribbling these thoughts while I wait for a clearing in the cloud. It is getting increasingly solid.
11:30 First prom capture NE quadrant. 1000 frames, 5.4ms, 117 gain, 640 x 480, 185fps. No real definition. Hedge prom at 2 o'clock.Overexposing but still faint with low contrast.
12:20 Central circle of dew still there. Dew bands now at 83F. It needs a door to squirt the hairdrier at the back of the lens. Getting breezy in the dome. 47/44F. Even more cloud.
I had to laugh: My wife refers to my crossing the yard to the observatory, with my laptop case, as "Like going off to work." After a pause, just now, I set off back to the observatory with a quip that I was getting back to the grindstone. To which my wife answered "grindstone cowboy!" 😊
12:30 Solid overcast. What a waste of a morning!
11:30 First prom capture NE quadrant. 1000 frames, 5.4ms, 117 gain, 640 x 480, 185fps. No real definition. Hedge prom at 2 o'clock.Overexposing but still faint with low contrast.
12:20 Central circle of dew still there. Dew bands now at 83F. It needs a door to squirt the hairdrier at the back of the lens. Getting breezy in the dome. 47/44F. Even more cloud.
I had to laugh: My wife refers to my crossing the yard to the observatory, with my laptop case, as "Like going off to work." After a pause, just now, I set off back to the observatory with a quip that I was getting back to the grindstone. To which my wife answered "grindstone cowboy!" 😊
12:30 Solid overcast. What a waste of a morning!
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