Sunspots Bloom

Holiday Display

On November 23rd, Thanksgiving day, the Sun displayed beautiful features. It happened to be a rare cloudless day in my part of the world! This imaging opportunity was too good to pass up, so I hauled my equipment outside in cool autumn conditions. Temperature ranged from 47 to 50 degrees while I worked in gentle breezes. It was comfortable in a light jacket. Unfortunately, the Sun was relatively low in the sky, and atmospheric seeing was mediocre. Nevertheless, it was thrilling to witness solar activity this day. The next image reveals why I was so happy. (Click on images to enlarge for better detail.)

The previous image is a mosaic consisting of 37 individual panels. I superimposed a 20-panel disc mosaic on top of a 17-panel prominence mosaic. Major sunspots appear in the left (eastern) hemisphere, and dramatic prominences are scattered all around the limb. A nice filaprom hangs on the eastern limb. Although this mosaic isn't perfect, it's one of the best I've ever produced.

There seems to be something like a quantum mechanical uncertainty principle when it comes to simultaneously capturing both disc and prominence detail. If exposures and processing are chosen to best show disc detail, then prominence detail diminishes. If exposures and processing are chosen to reveal prominence detail, then disc detail is overexposed and washed out. The only ways I know to exhibit both disc and prominence detail is to either superimpose two separate images, or to process disc and prominences separately within the same image. The first image above is an example of superimposing two separate images. The next image is an example of processing disc and prominences separately within the same image. It shows, diagonally up from left to right, sunspots 3500, 3494, and 3493 along with dramatic prominences on the limb.

The image above was captured at 9:37 EST. At 10:21 EST, 44 minutes later, the middle prominence had evolved into a faint, wispy structure shown in the next 3-panel mosaic processed to exhibit prominence detail. Notice how disc detail is overexposed and washed out in order to reveal the dim prominence. Also notice the nice "filaprom" (prominence to filament transition) farthest up on the limb to the left of the upper sunspot group.

The second large sunspot group, filaments, and a prominence are shown in the next image.

Sunspots above are, from left to right, 3491, 3492, and double umbra 3490. They make an attractive scene.

Two smaller sunspot groups along with the 3491, 3492, 3490 group are visible in the next image. It was constructed by cropping a 7-panel interior disc mosaic.

Sunspot group 3489, with three small umbras, is below center, while another small spot, 3498, is near the right edge. A larger view of sunspot 3489 is shown next.

Finally, I caught two small flares in progress before ending this observing session. The next two images show the first flare, a white overexposed area below double-umbra sunspot 3490. The top image was captured at 9:15 EST. The bottom image shows the flare erupting 83 minutes later at 10:38 EST.

The second flare appears as two white overexposed areas on either side of a dark filament sitting to the left of sunspots 3493/3494. The top image below was captured at 10:04 EST. The bottom image shows the flare eruption 20 minutes later at 10:24 EST.

Seeing conditions significantly deteriorated as noon approached signaling an end to this very productive observing session.