Saturday, October 27, 2012

New Barlow Lens

Enormous Prominence!

An enormous prominence hung above the Sun's western limb on October 21st. The prominence was near sunspot 1591 as seen in the image below.
Sunspot 1591 and Prominence (Click for full detail.)
The best of the remaining features was sunspot 1596, shown in the following image taken with a 2X Barlow lens giving a field of view about 10.4 arc minutes wide by 7.8 arc minutes high.
Sunspot 1596 imaged with 2X Barlow (Click for full detail.)
Below is the same sunspot imaged with the new 3X Barlow lens giving a field of view about 8.8 arc minutes wide by 6.6 arc minutes high. The increase in magnification is modest, but it does show some nice detail. The 3X image was taken a few minutes later than the 2X image above. Notice the change that has occurred during the few minutes between the two images.
Sunspot 1596 imaged with 3X Barlow (Click for full detail.)
Unfortunately, the new Barlow lens has introduced circular interference fringes into images it produces. These are caused by multiple reflections within the lens itself. You might notice these fringes in the right half of the image above. I'm investigating ways to remove the fringes through image processing.

Friday, October 19, 2012

Mediocre Seeing

Waiting For Solar Drama

Turbulent morning air on an extremely clear, crisp October 11th made images waver. Patience eventually revealed some brief patches of steady air and allowed three good images of sunspots scattered across the Sun. The first image below is a 3-image mosaic showing complicated sunspot 1589 on the left a few days after it came into view on the Sun's eastern limb. Isolated on the right is sunspot 1586.
Sunspots 1589 (left) and 1586 (right) (Click for full detail.)
Sunspot 1585 was about to depart over the western limb:
Sunspot 1585 (Click for full detail.)
I'm waiting for a more dramatic display of solar variety before the year ends. Lately, only relatively uncomplicated, small sunspots have been widely separated on the Sun. My final picture shows small sunspot 1590 just emerging from the sun's eastern limb. This image contains some good clear examples of spicules, the grass-like columns of rising gas seen near the top center of the image.
Sunspot 1590 (bottom center) (Click for full detail.)

Thursday, October 11, 2012

Sun and Shadow

Gossamer Filaments

The Sun had three sunspots, several filaments, and nice prominences on October 5th. Now, after the autumnal equinox, the Sun is getting lower each day, its light blocked by more and more trees as it travels across the sky. My observing window is shrinking. In another six weeks it will be very difficult to continue imaging. It's time to make the most of the remaining days.

Here is a 3-image mosaic showing two sunspots and one nice prominence.
Sunspots 1582(left), 1579(right) and a prominence (click for full detail.)
A more detailed view of the prominence in the image above shows arching streams of gas following magnetic field lines.
More detailed view of prominence (Click for full detail.)
Here's the same prominence alone, displayed with a new color.
The third sunspot showed activity in the white area below the spot.
Sunspot 1585 (Click for full detail.)
This 5-image mosaic shows how the three sunspots were arranged on the solar disk.
(Click for full detail.)
In the midst of my observing session the solar image suddenly disappeared from the computer screen. At first I thought the camera was malfunctioning. The screen showed bright and dark areas, but no curved solar rim and no solar features. Focusing didn't help. Just minutes before everything was perfect! What in the world was causing this problem? I got out from under my light-blocking cloth and looked at the front of the telescope. There I discovered a triangular shadow cast by my chimney covering three quarters of the front lens! In just a few minutes the shadow moved off the lens and a sharp solar image returned. This is what happens in my less than ideal observing location as the Sun gets lower in the autumn sky.

Here is a 3-image mosaic spanning the Sun's southern limb. Notice the filament-to-prominence transition visible on the left, the nice, flame-like prominence in the middle, and the diffuse, veil-like filament on the right.
Filaments and Prominences (Click for full detail.)
Here's a closer view of the gossamer filament seen on the right in the image above.
Gossamer filament (Click for full detail.)

Wednesday, October 3, 2012

Sun Near Equinox

Learning Mosaic Construction

Exquisite, clear fall weather accompanied the autumnal equinox in my portion of Virginia. September 23rd was an ideal day to use my new telescope mount for its first full observing session. The new mount performed flawlessly. I set the tripod legs on marks made previously, leveled the base, turned the mount on, and commanded it to point to the Sun. The Sun appeared almost exactly centered on the eyepiece cross hairs! Only a very slight azimuth adjustment was needed to make centering more exact. All morning the near perfect tracking and precise mount movements made solar observing a real pleasure.

The morning of September 23rd was about 24 hours after the autumnal equinox, and the Sun was very nearly on the celestial equator. On display were three nice sunspots and several filaments. I captured some good individual images showing lots of detail. The most prominent sunspots, 1575 and 1577 are shown below.
Sunspots 1577(left) and 1575(right) (Click for full detail.)
Sunspot 1577 and some filaments (Click for full detail.)
Here's a nice two-image mosaic showing a wider view of the two sunspots.
Sunspots, filaments, and some prominences (Click for full detail.)
I took enough individual images, 22 in all, to cover the entire solar disk. The precise N-S and E-W motions of my new mount made this task relatively easy. Unfortunately, it was not so easy to construct a high-quality whole-disk mosaic. When I attempted to combine all 22 images I got the following initial result, reduced here to one quarter of its original size.
Two things are immediately apparent. First, there are three notches in the Sun's circular rim because I got sloppy with my planned sequence of disk-covering movements. Second, the individual images vary in brightness and do not invisibly blend as desired. My version of Photoshop Elements, apparently, is incapable of successfully blending the images. Maybe the latest version would do the job. I don't know.

I spent many hours manually adjusting levels, but I could never produce a whole-disk mosaic without some of the dreaded patchwork appearance. It was possible to produce three, 4-image mosaics showing strips across the solar disk. Here they are in sequence from north to south across the Sun's equatorial region. (Click on each to see larger detailed views.)
It may look like these three strips could be combined, but the result shows unwanted visible borders where the images join. For example, here's the result of combining the top two strips. (Again, click for more detail. These images are about 4,000 pixels wide, but the blog format will not display them to full size.)
Notice the visible borders present in spite of my best efforts to eliminate them. Part of the problem is variation in image quality from one individual image to another. Sometimes the atmosphere is very steady for one image but not for the next one. The variation in image sharpness from one image to the next shows up as a visible boundary of changing sharpness. I'm beginning to think it may be impossible to produce a seamless whole disk mosaic at this image scale because there are too many changes happening while the images are recorded. I need to capture the entire disk with fewer images. This could be done with a bigger video camera chip, or by using less magnification. My plan is to try a 1.5X barlow lens instead of the 2X lens I have been using. Images will be smaller, but maybe I can capture the whole disk quickly enough with fewer images.   

People say I'm crazy doing what I'm doing
Well they give me all kinds of warnings to save me from ruin
When I say that I'm o.k. well they look at me kind of strange
Surely you're not happy now you no longer play the game

People say I'm lazy dreaming my life away
Well they give me all kinds of advice designed to enlighten me
When I tell them that I'm doing fine watching shadows on the wall
Don't you miss the big time boy you're no longer on the ball

I'm just sitting here watching the wheels go round and round
I really love to watch them roll
No longer riding on the merry-go-round
I just had to let it go

John Lennon