*
Wednesday 2nd Jan. 2019 36F: A clear sky but still blowing a gale! I went out after breakfast to have a look at a very slim crescent Moon and a 'hungry' half Venus through the 7" refractor.
It was already too light to ensure high contrast on the Moon. I pushed the power over 100x with the 20mm but it didn't help much. Venus was quite sharp but very bright even at 110x. So that it had a halo of light around it with its colour depending on focus.
The northerly wind was so strong it was blowing under the dome skirt and making my eyes water. I tried using my gloved hand to shield my face but then my hand became cold on the back.
I really must cut some curves from 2x4 timber to close off these gaps between the straight octagon sides and the 16 sided skirt. Which is a much closer approximation to a circle. As the rubber skirt will rub against this newly circular surface I had better ensure a smooth finish to reduce drag. Which means I can't just hack away with a wobbly electric jigsaw.
Ideally it needs a router but the great depth of cut is very time consuming and needs a very rigid radius bar. I could use my bandsaw followed by the disk sander. Though that would need a sharp and accurate line to work to.
One might think I could just clamp a router to the dome and rotate the dome around the building. Unfortunately the dome doesn't track so accurately that it can be used as a tool guide.
Later I found some off-cut arcs of ply from cutting out the shutter ribs. By clamping these to the top ring I was able to exclude most of the wind. A far more positive result than I was expecting. Which suggests I go ahead with my arcs of 2" thick timber to make the top ring fully round instead of octagonal.
I really must cut some curves from 2x4 timber to close off these gaps between the straight octagon sides and the 16 sided skirt. Which is a much closer approximation to a circle. As the rubber skirt will rub against this newly circular surface I had better ensure a smooth finish to reduce drag. Which means I can't just hack away with a wobbly electric jigsaw.
Ideally it needs a router but the great depth of cut is very time consuming and needs a very rigid radius bar. I could use my bandsaw followed by the disk sander. Though that would need a sharp and accurate line to work to.One might think I could just clamp a router to the dome and rotate the dome around the building. Unfortunately the dome doesn't track so accurately that it can be used as a tool guide.
Later I found some off-cut arcs of ply from cutting out the shutter ribs. By clamping these to the top ring I was able to exclude most of the wind. A far more positive result than I was expecting. Which suggests I go ahead with my arcs of 2" thick timber to make the top ring fully round instead of octagonal.
Even at 10am I can see the shadow of the trees and hedges cast onto the lower half of the dome. So it will be a while before I can get a clear view of the Sun in H-alpha.
Eventually I took some afocal snaps with my Lumix TZ7 at the eyepiece using a Green Solar Continuum filter. A chain of small spots is ringed in the attached image. Then I tried the Neximage5 in trying to capture the spots in closeup. The problem is that a year has passed since I used the camera and iCap software. So I can no longer remember much about the settings. I took a few stills and left it at that.
In H-alpha the spots are surrounded in a large pale oval. There are prominences at 3 o'clock and 9 o'clock. I went on trying to capture what I was seeing but was generally disappointed with afocal snaps and the Neximage5.
I was trying to take an afocal snap in H-alpha when my down jacket cuff suddenly started smoking from the focused finder image. Fortunately it is an old jacket which I usually wear in the workshop too. No obvious damage done. I have been using the finder's projected solar image inside its own shadow projected onto the dome to quickly center the telescopes. I shall have to make a pierced objective cap to greatly reduce the focused heat!
The wind picked up after lunch but the shelter of the dome allowed me to remain in relative comfort despite the breezes wafting about inside. The open areas under the floor meant there was a proper gale blowing around "downstairs."
Eventually I took some afocal snaps with my Lumix TZ7 at the eyepiece using a Green Solar Continuum filter. A chain of small spots is ringed in the attached image. Then I tried the Neximage5 in trying to capture the spots in closeup. The problem is that a year has passed since I used the camera and iCap software. So I can no longer remember much about the settings. I took a few stills and left it at that.In H-alpha the spots are surrounded in a large pale oval. There are prominences at 3 o'clock and 9 o'clock. I went on trying to capture what I was seeing but was generally disappointed with afocal snaps and the Neximage5.
I was trying to take an afocal snap in H-alpha when my down jacket cuff suddenly started smoking from the focused finder image. Fortunately it is an old jacket which I usually wear in the workshop too. No obvious damage done. I have been using the finder's projected solar image inside its own shadow projected onto the dome to quickly center the telescopes. I shall have to make a pierced objective cap to greatly reduce the focused heat!
The wind picked up after lunch but the shelter of the dome allowed me to remain in relative comfort despite the breezes wafting about inside. The open areas under the floor meant there was a proper gale blowing around "downstairs."
*
No comments:
Post a Comment