Sun (H-alpha), 12/31/2004

by Marek Cichanski


Despite all of this rainy weather, I managed to have a very nice solar viewing session just now. It felt really good to do a bit of observing in between storm systems.

I set up the ED80 and the SM40 / BF10, and I took a look at 'ol Sol. The seeing was very steady at about 10am. I have found that the amount of detail that I can see on the sun is very dependent on the seeing. Going from mediocre seeing to very good seeing is almost like throwing on another etalon. This was one of those sessions. It still takes a lot of observing effort to tease out all of the available detail, but after a few minutes my eye and brain get used to the monochromatic light, and they're able to get the most out of the image.

The preceding and following limbs of the Sun had large, blocky-looking prominences. They were rather different from the more filamentary ones that I usually see. There were some tiny, delicate, thin little prominences along the south limb. The chromospheric layer was nicely visible all around the limb, with some traces of 'spicule' structure in it. There was a beautifully crisp, sharp-edged, arc-shaped filament near the center of the disc. (I think that these filaments are simply prominences seen from above.) And a bit to the east of the center of the disc, there was a nice active region. It had what appeared to be a single sunspot, surrounded by dark, nearly circular structures. It reminded me of satellite images of Lop Nur, a big dry lake bed in the desert of western China, which resembles an ear when seen from above. There was also a good deal of mottling on the surface of the Sun, which was nicely visible due to the excellent seeing.

As I've said before in this space, one of my favorite things in amateur astronomy is 'getting away with it' when the weather is bad. This was a prime example. Makes up for a good bit of rain. Let's hope that the sky clears in time for the next dark moon cycle!


Posted on sf-bay-tac Dec 31, 2004 10:41:14 PT
Converted by report.pm 1.2 Jan 24, 2005 19:46:24 PT