Solar Imaging

With the frigid temperatures outside being down in the single digits and sub-zero range everyday, I've been trying to keep busy indoors.  Of course, by saying "I've been trying to keep busy" I am referring to keeping busy in the little bit of spare time I have between health issues, daily physical therapy, daily piano practice, and down time.  Still, I like to accomplish something and learn something each day regardless of whether it is a good health day or bad health day.  

The windy frigid temperatures have kept me indoors.  I don't even like going outside to get the mail in this weather so Sheila does that most days!  As I've written in this blog often, my health fares quite poorly in warmer environments (in the 80s and above) but I've been very sensitive to cold environments also as I approach 60 years old (in a few months, in case anyone wants to know).  I simply have zero tolerance for cold environments now.  (Watching the grandkids at the ice rink is brutal and even painful!  I'm very uncomfortable, feel lousy and can hardly move after about 30 minutes or so in an ice rink as a spectator.)  When I am uncomfortably cold I do not enjoy anything.  This is especially true after recovering from frostbitten fingers a little over a year ago.  

During these long periods spent indoors, I sometimes go back through old photos.  In this case, I spent some time revisiting some relatively recent solar imaging I had done before our first snowfall this winter.  I wasn't happy with how these images turned out and had always hoped to find a better way to squeeze out a bit more detail.  Those initial images just didn't look right.  Part of the problem was due to the fact that I was using new unfamiliar equipment and compounding this was the fact that this new equipment was capturing light in a very different wavelength than I had ever captured previously.  This frigid cold snap being spent indoors seemed like a good time to do some refining of my processing skills for this type of imaging.

In this case, I was imaging in the Calcium K spectrum rather than the white light spectrum. This Calcium K spectrum is specifically centered at the 393.3nm wavelength.  The sun shows a bit of a different layer at this wavelength than I had ever imaged in the past.  Up until this point, I had only imaged the sun in white light which shows us the photosphere.  This particular Calcium K (CaK) filter shows us a layer sort of between the photosphere and the chromosphere.  (Imaging the chromosphere in more detail in the Hydrogen Alpha wavelength will be next on my list.)

When I posted an image a few months ago from this last solar imaging session in CaK, I was not at all happy with the results.  I believe the biggest problem was that the seeing conditions were very unsteady.  The sun was stretching and contracting back and forth, up and down, side to side, like a rubber band being stretched to its limits.  This was due to evaporation on Earth radiating up into the atmosphere creating convection currents.  The view in bad seeing is sort of like looking across a big blacktopped parking lot on a hot sunny day with wavy convection currents rising from the blacktop visibly distorting your view with a wavy shimmering effect.  This is how the sun looked on this particular day.  I don't get too many good astronomy days here though so I went ahead with my imaging session anyway.  The results of this imaging session, at the time, were not all that impressive.  I was hoping I could improve upon it this time around.

A couple of days ago, I decided to learn how to use a new piece of software that makes processing these type of astronomy images a little easier.  The software uses computer calculations and evaluations to choose the best images and then stacks them.  Stacking multiple good images provides a better image than a single good image if the stacking is done correctly so I needed to figure out how to use this program.  I had previously been choosing only a very few of the best images manually and then manually aligning and stacking them.  This was a very tedious and time-consuming process that simply did not work well and especially when the seeing conditions were poor.  

I had some success at learning more about this particular stacking program so I ended up with a significantly better image this time around.  I think this might be the best image I can get out of those lousy seeing conditions.  It is certainly a far better image that my first attempt a few months ago!

What we can see in this image, above, is granulation, supergranulation, faculae, and the umbra and penumbra of a sunspot.  

If I remember correctly, I only had about 130 images in total due to clouds significantly limiting my imaging time and, since the seeing conditions were so poor, most of these images were terribly distorted, fuzzy and lacking detail.  I ended up stacking only the best 20% of these meager 130 images.  This is far less than ideal.  That being said, I think the above image is quite nice for such terrible conditions and it actually resembles a proper CaK image...  finally!  

The sun is purple in this image because this wavelength, 393.3nm, is actually in the purple/blue range of color.  Our eyes don't see this color all that well so using a camera to capture images and video is the only way for us to "see" what is happening at this wavelength.  Really, I could change the color to whichever color I desire but this purple color is actually used for CaK imaging in the scientific community so this is the way I chose to present it here.  This way we know it is a CaK image at first glance without having to read the specifics about the image. 

I'm looking forward to imaging in CaK more when the weather becomes more tolerable and the skies are clear.  I have a few other ideas to try so I could use some new data!