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Sunday: The weather forecast is promising sunshine. In variable amounts. Best clarity early on. Completely calm at present.
I haven't had a chance to try the new geometry of the H-alpha 6" [120/10] since changing the etalon distance from focus to the expected 200mm for a modified PST. The distance was previously too short by 20mm.
The sky has been very hazy or very cloudy. I should have my chance today provided the optics don't dew over. It is just below freezing at the moment. [08.00.] Still waiting for the sun to rise despite an official sunrise of 7.23am. There are the first signs of a shine on the dome.
0930 CET: 41/38F clear and still. Sun at 16° altitude. Blank in WL.
The dark filament is reduced to a small C-shape. With pale areas [plage] surrounding it. I am still adjusting the etalon and focus to try and bring out more detail. No proms so far. GONG H-a showing no proms and a smudge for the filament.
10.00am The filament is now only a short straight line and difficult to see. It is now forming a dark edge to a lighter spot.
After this I wrote half a page of my usual diatribe only to lose it somewhere between the laptop and the PC when I went in for elevenses.
13.00 54/49F Thin, high cloud moving across from the WSW. Still struggling for surface texture in H-a. I have removed the etalon and adjusted everything. No magical fix. I have opened the veranda doors to clear out any excess warmth in the dome. Breezier than before but the temperature differential between out and in is almost unchanged.
After hours of pointing at the sun the Lacerta heat sink is only slightly warm to the touch.
Added a spacer to the rear end of the etalon adapters to take up the slack. Surprisingly, I now have much more even surface texture but still, rather low contrast. One very tiny prom at my 8.30. At least I now have a reference for etalon tuning.
13.30pm 53/50F [improving] but the sky is becoming ever more milky from thin, high cloud becoming denser. Lunch. Even more cloud after lunch. Parked the scopes.
0930 CET: 41/38F clear and still. Sun at 16° altitude. Blank in WL.
The dark filament is reduced to a small C-shape. With pale areas [plage] surrounding it. I am still adjusting the etalon and focus to try and bring out more detail. No proms so far. GONG H-a showing no proms and a smudge for the filament.
10.00am The filament is now only a short straight line and difficult to see. It is now forming a dark edge to a lighter spot.
After this I wrote half a page of my usual diatribe only to lose it somewhere between the laptop and the PC when I went in for elevenses.
13.00 54/49F Thin, high cloud moving across from the WSW. Still struggling for surface texture in H-a. I have removed the etalon and adjusted everything. No magical fix. I have opened the veranda doors to clear out any excess warmth in the dome. Breezier than before but the temperature differential between out and in is almost unchanged.After hours of pointing at the sun the Lacerta heat sink is only slightly warm to the touch.
Added a spacer to the rear end of the etalon adapters to take up the slack. Surprisingly, I now have much more even surface texture but still, rather low contrast. One very tiny prom at my 8.30. At least I now have a reference for etalon tuning.
13.30pm 53/50F [improving] but the sky is becoming ever more milky from thin, high cloud becoming denser. Lunch. Even more cloud after lunch. Parked the scopes.
Click on any image for an enlargement.
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