A Beautiful Afternoon for Solar Astronomy

Yesterday afternoon was a little chilly but a beautiful afternoon for solar astronomy.  The sky was a deep blue, the distant mountaintops were crisp with no haze diminishing my view, and the temperature was a balmy 20° or so.  It was a great opportunity to spend a little more time with this new solar filter.

I set up everything indoors and then moved everything to our mudroom/laundry room at the back door to make it easier moving everything outdoors.  I knew I wanted to attempt to capture some photos so I also had two cameras ready as well as a few lens choices.  

You can clearly see in this first photo that it was a beautiful afternoon.  I don't think I've seen skies this clear in years!

I was able to set up the telescope in an area where I had cleared snow the previous night.  This area of the backyard is very near our outdoor kitchen and the back door to the house so I had easy access to any additional equipment I might need from indoors.  

Although it was a relatively moderate winter day, it was still winter and cold enough to need to dress warmly.  Since I have no desire to get frostbitten fingers again, I dressed very warmly and minimized my time outside.  This was a longer session than I had done since autumn but it still was not much longer than an hour.  Since I was trying to keep this session relatively short, I didn't want to take the time to set up and align a tracking mount.  This meant that I had to constantly nudge the telescope on a manual mount in the direction that the sun was moving across the sky.  This also meant photography would be challenging but I figured it would be well worth a try even if I only got one decent image.

Below is a photo of the sun which is actually an image taken from a single frame that shows what this new solar filter is capable of producing.  I mention that this is a single image because astronomers should never shoot just one image.  You want to stack many images for a few reasons I won't get into here other than to say that stacking many images results in far better final images.  Next, you should always use a camera that is appropriate for astro imaging.  In this case, for solar imaging, I should have been using a monochrome astro camera.  My Sony cameras are great cameras for all land-based imaging but they are not even close to ideal for astro imaging.  I lose an awful lot of fine detail and resolution by using my normal Sony camera instead of a monochrome astro camera.

Regardless, I used one of my Sony cameras for these solar images because any astro camera would require the use of a computer for image capture and that would require far more setup time.  Since I was insistent on avoiding frostbite, time was not on my side in this 20° weather.  I still had more than an hour to observe and image the sun but having to setup a computer too would have easily doubled the time I would be outside.  If I brought out a computer, I might as well set up a tracking mount too.  Instead, I kept things as simple as possible...  challenging, but as simple as possible. 

When I finally get to build my observatory, all of this will be much, much easier.  I'll have a computer ready to go only a few feet from the telescope, I'll have easy access to a tracking mount, and I will be able to stay warm.  Maybe that project will be completed in the coming months if lumber becomes available and at reasonable prices, the pandemic slows down, the weather cooperates, and my health cooperates.

So here is a full disk image of the sun in hydrogen alpha that I shot yesterday...

It is more obvious in the image below but, in both of these images, you can see a wavy ripple effect.  This is called Newton's Rings and they are an imaging defect that astronomers try to avoid.  The effective way to avoid getting Newton's Rings in your images is to use a tilt adapter to slightly tilt the camera but I do not own a tilt adapter.  I made do with what I had on hand.  I removed my eyepiece, slipped the camera into the eyepiece holder and used a wireless remote to capture images.  I knew I'd end up with Newton's Rings so I knew I would have to accept this rather annoying defect for now.  At least I was expecting it so that made it easier to accept these Newton's Rings.

The next image is a closer view of the eastern limb of the sun.  As I was observing, I noticed there was a lot going on here so I wanted to capture a quick photo.  I rotated this eastern limb so the prominences were shooting upward away from the sun.  

I was observing for long enough that I was seeing motion in the prominences.  Some prominences developed, rose from the surface of the sun and then dissipated 10-20 minutes later.  Some prominences changed shape.  Someday I hope to capture a time lapse video of an interesting prominence developing, shooting plasma away from the sun, slowly changing over time and dissipating.  These changes occur so slowly over time because we are seeing details across thousands of miles.  

Overall, these first two single frame images turned out great especially considering the challenging equipment I chose to use on this chilly winter day.  I'm quite happy with these results.  Actually, I'm pleasantly surprised by how good these two images look!

As good as these two images turned out, the observing was more exciting and crisp than we see in these photos.  It was an outstanding observing session.  

EDIT - 28 February 2022:  Since first publishing this blog entry, I decided to revisit editing these two solar images.  The above solar images are the newly edited versions which show finer detail and look more pleasing overall.

EDIT - 1 March 2022:  In a previous blog entry, I wrote about the first time I used this new solar filter and how frigid it was outside.  I only spent a few minutes outside to view the sun and didn't spend any time actually tuning the filter to get it on-band.  This filter needs to be tuned each time you use it to see the most detail but I haven't spent any time out in the cold trying to find where on-band would be.  

I didn't do any tuning on this day either.  Actually, my tuning may have been far off-band because, after being out there for about an hour, I noticed that the tuning knob was turned to a position far from neutral.  So, I know the filter was not tuned on-band.  I don't think I'm going to do much with tuning until the weather is considerably warmer.  I wanted to point out that I know these images aren't the best and that my filter was likely well off-band.