Six Sunspots

Pleasant Observing Conditions

Although the sky over my Virginia observing site remained hazy from Canadian wildfire smoke on June 5th, only a few widely scattered clouds were present. Occasional light breezes and temperature ranging from 63 to 67 degrees made morning observing conditions very pleasant. The Sun presented six sunspots and several filaments shown in the following 23-panel full disc mosaic. Solar activity is continuously increasing!

The previous image was processed to show disc features. Details show well when you click on the image to enlarge it. Different processing reveals prominences around the solar limb in the next image where the disc is, consequently, overexposed.

Four sunspot areas along with filaments and a prominence are shown in the next scenic portion of the solar landscape. From left to right are active area 3327, then elongated sunspot group 3323, then large umbra 3321. The small umbra of sunspot 3320 is in the upper right corner.

A slightly different region is portrayed in the next image which shows the dark umbra of sunspot 3326 in the upper left corner along with 3323, 3321 and 3320. Sunspot 3325 sits near the right edge.

View the next image of 3323 and 3321 at full size to see complex structure in best detail.

A diffuse filament floated near the top of Sun. The 2nd inverted image emphasizes cloud-like filament elevation.

Filaments across the disc float nicely above the surface in the next inverted disc portrait which shows best at full size.

I was able to capture images for only one hour before increasing clouds closed the observing window. Images showed good detail in spite of mediocre seeing.
 

Fading Solar Flares

Eruptions Decay

During my last solar observing session on May 22nd I was able to see two solar flares. Although I missed the initial development of each flare, I was able to make small time lapse animations of their decline. The flare in active area 3312 faded away over 20 minutes between 9:47 and 10:07 EDT as shown in the first animation below:

(The individual frames in these animations run from start to finish in an endless loop.) The flare seems to sink into the background.

The other flare, in sunspot 3311, disappeared in only 10 minutes from 10:14 to 10:24 EDT as you can see in the following 11-frame animation:

Each individual frame in these animations was obtained by stacking the 100 best frames from a 1,000-frame video. I recorded one video clip every 60 seconds.
 

Solar Flares and Smoke

Unlucky Timing

More than a month of cloudy weather followed my last solar imaging session. Finally, on May 22nd, clouds cleared. Unfortunately, the sky was a hazy white instead of blue. Conditions were otherwise quite pleasant with temperature ranging between 63 and 70 degrees. A fair number of sunspots and prominences were visible as you can see in the following full disc image, an imperfect 20-panel mosaic.

Separate mosaic panels did not blend well below center, so a vertical line of brightness difference runs down the middle of the mosaic. My monochrome camera produces black and white images to which I later add color. The next image is the same mosaic as above, but colored to approximate the red hydrogen-alpha light I see visually through my telescope's eyepiece.

In the first moment my camera became operational I noticed how dim the video preview was. I had to increase camera gain and adjust the "gamma" in order to see something similar to what I would normally see on a clear blue sky day. The white hazy sky was definitely attenuating light! The haze was caused by smoke blown eastward from distant western Canadian wildfires. The next two satellite images show the smoke over much of the USA and penetrating into my home state of Virginia.

Smoke degraded my images, but interesting things showed up anyway. An active string of sunspots in the Sun's northeast quadrant pointed toward a hazy "filaprom" on the nearby limb. This is the most detailed image I captured and shows well at full size.

Complex multi-umbra sunspot group 3311 is located between sunspot 3313 on the left and 3314 on the right. Soon after this image was captured a solar flare exploded in 3311. More on this below.

The other major sunspot was 3310 whose umbra dominates the next image below. To the left of 3310 is an area of white energetic emission called active area 3312. Area 3312 also emitted a solar flare near the same time as 3311's flare.

Sometimes changes happen rapidly on the Sun. It takes luck to be observing the active part at just the right time. For example, at 9:06 EDT I saw the following erupting spike prominence coming off the limb from departing sunspots 3308 and 3305.

If I had started imaging sooner, I would have been able to watch this grow in real time. Instead, I saw it slowly evolve into the following small arching prominence 10 minutes later at 9:16 EDT.

Unlucky timing continued. Images for the following 5-panel mosaic were obtained between 9:23 and 9:26 EDT.

Twenty one minutes after 9:26, at 9:47 EDT, I moved back to sunspot 3310 and discovered active area 3312 (to the left of big umbra 3310) was flaring. The flare shows up as a white overexposed area at 9:47. (Compare with the 9:26 mosaic above.)

For the next 20 minutes I watched this flare fade away. I had missed the flare rising. Then I moved up to sunspot group 3311, north of 3310, and saw a flare in 3311 at 10:14 EDT! Once again, the flare is a white overexposed area in the next image. (Compare, again, with the mosaic above.)

Once again I missed the flare buildup! I could only watch it fade away over the next 10 minutes. Sky conditions worsened and it was time to quit. In spite of unlucky timing it was still exciting to see two flares on the same day.
 

Astrophoto Trial and Error

Slowly Learning

Evening skies remained beautifully clear following my afternoon solar imaging session on April 12th. After sunset observing conditions were ideal with low humidity, no dew, no wind, no moonlight, and temperatures in the 60's! I set up my 130 mm Stellarvue refractor and Nikon Z6 2 camera for another attempt at astrophotography. As twilight faded I took a quick 2-second exposure of Venus near the Pleiades with the Nikon mounted on a fixed tripod. ISO was set at 1600 and the f/2.8, 24-70 mm lens was set to 70 mm. Venus was closer to the Pleiades a few days earlier, but this pairing was still nice.

With the camera on the telescope I captured dark frames and flat fields in order to improve image quality. Dark frames are easy to get - just cover the telescope aperture with a lens cap and capture what the camera records when no light falls on the detector. Ideally, when no light falls on the detector, it should record zero for every pixel across the field of view. A real detector, however, does not read zero across the field. If the dark frame has the same exposure time as an actual image of a celestial object, then the non-zero dark frame detector response can be subtracted from the image to leave a result not degraded by false signal.

A flat field image is the image of a uniform light source across the field of view. Ideally, the camera detector should record an image of a uniform light source that is absolutely uniform across the field of view. Unfortunately, a real camera's response will not be absolutely uniform because pixels vary somewhat in sensitivity, or because some dust or dirt on the detector blocks pixels, or because the optical system doesn't produce uniform light across the detector. My Nikon exhibits significant vignetting - images are brighter in the center and darker at the edges. So I need to record a flat field image to correct real images from non-uniform detector response. 

Producing a uniform light source for the telescope in my backyard is inconvenient. For this session I covered the telescope aperture with either a single sheet of white paper, or a white cloth. I then illuminated the paper or cloth with an LED light held at some distance. This method was partially successful, a definite improvement over no flats at all, but it wasn't perfect. I still had to sacrifice dim image detail in order to make sky background uniformly dark.

Here are some results from April 12th. First is an image of the edge-on galaxy NGC 4565 in the constellation Coma Berenices made by stacking eighteen, 10-second exposures with ISO set at 6400.

Click on this image to view it at full size and notice the small smudge below galaxy 4565 at the end of a curved string of 5 stars. This smudge is spiral galaxy NGC 4562. If you look closely at the full size image, you might just make out a tiny grey fuzzy object about half of 4565's width distant on the left side of 4565. This is a 14.6 magnitude spiral galaxy, IC3546.

NGC 2903, a barred spiral galaxy in Leo, is shown in the next image made by stacking nine, 15-second exposures at ISO 25600. Once again, the full-sized image shows the most detail and reveals the bar and some spiral structure.

Also in the constellation Leo, a trio of galaxies fit nicely in the camera's 2.3 X 1.53 degree field of view. The next image was made by stacking eight, 15-second exposures at ISO 25600. From top to bottom the "Leo 3" consists of galaxies M65, M66, and edge-on galaxy NGC 3628. This image is a significant improvement over my previous attempt on March 4th. The longer exposure time and darker moonless sky made a big difference. Some details of galaxy structure are visible when viewed at 100 percent.

The next picture is the Whirlpool Galaxy M51 in the constellation Canes Venatici made by stacking eight, 15-second exposures at ISO 25600.

The four previous galaxy pictures were made without a Barlow lens. All of them beg for greater magnification and longer exposures. The image scale is also too small to display the full amount of fine detail present in the best images of these galaxies. Nevertheless, I was pleased with the improved image quality compared with my last attempt on March 4th!

Another magnificent clear, mild, moonless night occurred on April 18th. On the 18th I tried three new things. First, I lowered ISO setting to 1600 to see if image noise could be reduced. Second, I increased exposure times. Third, I tried a few images with a 2X Barlow lens.

The next two images are the galaxy pair M81 and M82 in Ursa Major. The first image, from April 12th, was made by stacking twenty, 8-second exposures at ISO 12800. The second image, from April 18th, was made by stacking twenty, 30-second exposures at ISO 1600.

There doesn't seem to be much difference between the two previous images. The longer exposure at lower ISO in the bottom image didn't reveal more detail. Perhaps a longer exposure at higher ISO would have revealed more.

What about higher magnification? The next two images of globular cluster M13 in the constellation Hercules show the effect of adding a 2X Barlow lens. The first picture, from April 12th, was made with no Barlow by stacking nine, 15-second exposures at ISO 6400. The second picture, from April 18th, was made with a 2X Barlow by stacking twenty, 30-second exposures at ISO 1600.

The second magnified M13 image does show more stars and begins to display some orange/yellow color of older stars. There's not enough magnification to resolve individual stars in the cluster's center, however. I'd like to try longer exposure time on this in the future.

Finally, galaxy M108 and planetary nebula M97 in Ursa Major are close enough to form a beautiful pair in my camera's field of view. The next image was constructed with no Barlow lens from twenty, 30-second exposures with ISO at 1600. The colors of planetary nebula M97 show up well, but the galaxy lacks detail. These objects deserve more magnification.

I installed a 2X Barlow lens and took another twenty, 30-second exposures at ISO 1600 to get a magnified view. Unfortunately, as the next image shows, the result is dimmer because object brightness was spread over a larger area.

Once again, I'd like to return to this pair and double or triple exposure time.

It looks like on a given night I'll have to limit the number of different objects I photograph to spend more time exposing a selected few. Unfortunately, there's no way to avoid an intense, glaring light shining directly on my observing site from a neighbor's window. This light will sometimes get turned off after midnight, but often it's left on all night long! Anyway, it will be at least another few weeks with clouds and moonlight before conditions will allow another astrophotography attempt.


 
 

Scattered Sunspots

Nice Prominences

It took two months for a dominant high pressure system to arrive and clear away persistent daily clouds. On April 12th only thin haziness kept skies from being completely clear. I set up my solar telescope in late afternoon and didn't begin imaging until 3:22 pm (EDT). Morning is usually preferable for solar imaging. I worried about bad seeing, but seeing was reasonably good. It was lovely to bid chilly winter goodbye and enjoy working in temperatures ranging from 78 to 81 degrees with hardly any wind.

No large sunspot umbras were present, but lots of smaller ones were scattered among stringy filaments as you can see in the following 20-panel mosaic processed to show disc detail. Each individual panel is a stack of 400 video frames from a 4,000-frame video.

The most interesting features are active area 3272 just below center and active area 3276 rotating into view near the solar limb on the left.

The next image is a close view of 3272 showing a complex arrangement of tiny umbras set among white energetic emissions. These show up nicely when the picture is viewed at full size. Our view from Earth looked down from above on a beautiful example of dark magnetic arches to the upper right of the umbra region.

The eruptive nature of active area 3276 is seen in profile near the eastern limb in the next two images.

A good variety of prominences were spread around the limb as you can see in the next 18-panel mosaic processed to enhance limb features. (Consequently, the disc is overexposed.)

The next two images show enlarged portions of the most interesting limb sections.

Haze was forecast to disappear later on the evening of April 12th. I took down the solar telescope and mounted my 130 mm refractor for possible night observing. The nighttime session will be the topic for my next blog post.

Pleiades/Moon Conjuction

Quick Photo

Cloud cover forecasts at my location are often inaccurate. When I glanced outside on March 25 after sunset it was unexpectedly clear with a crescent Moon above the western horizon. Clear skies don't last long these days, so I hurried to set my camera on a tripod. I took several quick exposures to see if I could capture earthshine on the Moon. The following image is the best of the bunch.

It turns out the Moon was passing close to the Pleiades cluster! Of course, I should have known this and set up a telescope in advance to get a much better picture, but I expected cloudy skies.

The lunar crescent is overexposed and the Pleiades are underexposed. A longer exposure to brighten the Pleiades would make the crescent even more saturated. Now I'm curious to see how well my 130 mm refractor would render a scene like this at higher magnification.

The image above is cropped from a 2.5-second exposure with a Nikon Z6 2 camera. The lens was set at 40 mm, f/2.8, and ISO was 100. 

World War I Airplanes

Old Warplanes

During my annual visit to the Military Through the Ages exhibition this year at the Jamestown Settlement Museum I came across two displays I'd never seen before. First was a French biplane shown below.

This plane was armed with a machine gun whose firing mechanism was synchronized with the propeller so bullets wouldn't destroy the blades.

The fabric and wire construction of these planes seems incredibly fragile compared to modern fighters. Cloth and wire weren't much protection from machine gun bullets! Nearby was a German plane from the same war.

A smaller machine gun fired forward from the German plane.

Cockpit controls seem extremely primitive!

The German plane was a Fokker E3 whose features are described below.

Among the many reenactors attending this year's exhibition was a group portraying The Devil's Nightmare Regiment from roughly the year 1529. They always present a colorful display of weapons, costumes, and living customs from this time period. I found their recruitment poster particularly amusing.

It's always a pleasure to visit this wonderful exhibition each year, especially on a mild sunny day!