April 8th 2024 Total Solar Eclipse: Fine Detail in Corona

I went down a bit of a rabbit hole this week, assuming that to really get sharp detailed images of totality I needed to go through the rather involved process of using calibration frames to process all of the images I planned to stack before trying to stack, register and merge them. After spending a few evenings starting down that road, I took a break and in reviewing tutorials on processing solar eclipse images I ran across several that describe doing everything directly in Photoshop without the use of registration frames. 

Following the process described in this Sky & Telescope article, I created the image above using a set of images shot at 2 stop intervals from 1/4000th of a second to 1 second, all shot at f/5 and ISO 100 with my Nikon D750 through our Sky Watcher Evostar 72ED telescope. 

Click on it to enlarge and check out the incredible detail. You'll find features like:

• Plenty of detail in the solar corona
• Solar prominences
• The lunar surface illuminated with light reflected from Earth (Earthshine)
• Several stars from the constellation Pisces

This is just the first phase of edits described in the article so more to come. In the meantime, I did a separate version with features labeled. 

April 8th 2024 Total Solar Eclipse: Initial Telescopic Images

Fine details in the solar corona

One of my primary goals for this total solar eclipse was to capture a variety of telescopic views of the eclipse. The similar goal I had in 2017 was spoiled by overcast skies that resulted in a mad dash down the road with Beau Hartwig chasing clear skies. Seeing totality with my own eyes meant giving up on my photographic goal. I don't regret that for a minute but I was thrilled that this time the skies cleared for us just in time for the "Big Show". 

To avoid having to split my attention between experiencing totality and taking pictures, I used our old 2012 MacBook Pro running a software package called Solar Eclipse Maestro to control the camera, snapping pictures at pre-defined times and exposure settings. SEM worked flawlessly and had it not been for a user-error on my part (which I'll cover in a future post), I would have captured everything I planned for. As it is, I still was able to capture most of what I planned including:

• Diamond Ring effect (though not as spectacular as that from other people due to my snafu)
• Baily's Beads effect
• Solar corona fine detail
• Earthshine (lunar surface illuminated with light reflected from Earth)
• Partial phase images (though I missed much of the first half of the eclipse due to clouds)
• a full set of images and calibration frames I have submitted for the NASA-based science project called the Eclipse Megamovie

Although the images captured were as good or better than I hoped, post-processing them to fully bring out the available detail is a rather complicated thing involving a variety of software tools. I am still working on that but I wanted to go ahead and share some initial edits. 

The image above is a blend of each of the 19 different shutter speeds used to capture images to submit to the Eclipse Megamovie project. They were taken during totality to capture as much fine detail of the solar corona as possible. The project team will use the calibration frames to pull out even more detail than appears in this image but, for my first pass at this I used some basic stacking techniques in Photoshop. Click on it to see enlarged... isn't the level of detail incredible?

I'm also including some cursory edits I've done of a few other images below including a partial phase image and a picture of Baily's Beads. What I am the most excited about though is the spectacular solar prominences that appear in the Baily's Beads shot. Wow! Even more incredible is that the largest one was visible naked-eye. 

Once I've had time to go through the rest of my images and finish some of the more complicated editing processes, I'll share more of these. I'll also do a follow-up post on my equipment and what went into capturing these images. 

I hope you got a chance to see totality for yourself but, if not, please enjoy my first pass at sharing the view with you. 

Late in the partial phase of the eclipse. Note the sunspot in the center!

  

Baily's Beads and Solar Prominences

The Green Comet

Well, the first thing that came to mind seeing news headlines about The Green Comet was a flashback to the 60s TV show The Green Hornet staring Bruce Lee. :-)

Seriously, this has been a newsworthy comet. While it wasn't bright enough to be seen except under very dark skies and/or with optical assistance like a telescope, as you know if you've followed the news, it is a singularly unique solar system visitor. Check out sites like EarthSky.org for more details and some of the more interesting images. 

For my part, I had hoped to capture comet C/2022 E3 (ZTF) with my rig (Evostar 72ED on a Star Adventurer tracker, using a Nikon D750). Unfortunately, the North Texas weather hasn't cooperated. Last week when it was at its closest to Earth (and at its brightest magnitude), we were in the throes of a winter storm. By the time we had a night with relatively clear skies on Friday night, we also had a nearly full Moon. It was also still very cold outside. If it had been a moonless night, I'd have packed things up and headed out east of town to darker skies to shoot but since I knew the Moon was going to make it hard to get really good shots, I just set up in my backyard. At least I could duck inside from time to time to warm up. 

Here is the result. See below for more on how it was created. 

Comet C/2022 E3 (ZTF) captured in my backyard
February 3rd, 2023

Between the light pollution and the glare of the Moon, it was hard for me to pull out much detail but you can at least see the dim fuzzball of the comet's core. The comet was in a region of the sky without any bright stars but the few brighter ones on the right side of the image are in the constellation Camelopardalis.

Still, it was time well spent. It was the first time I've gone through the process of capturing what are called calibration frames (bias, darks, flats), additional shots taken to improve astrophotography images by accounting for things like sensor noise and dust. It is also the first time I have processed using calibration frames; I took 100 images (20 seconds each) and post-processed them and the calibration frames using a software tool called Siril and then finished in Photoshop. 

Capturing a comet is often tricky since it is moving at a different rate than the stars. Using a star tracker (vs. a telescope mount), my only choice was to track the stars and hope to be able to post-process the comet and stars separately then combine them afterwards. I did that but it took a long time and many tries just to get the results above. I wish I had more data but longer exposures weren't possible since the histogram showed that any longer than 20 seconds at ISO 3200 would have resulted in clipping (i.e., the blue was almost lost to the right side at 30 seconds). On top of that, the comet would have blurred if I used too long an exposure given how fast it was moving.

One of the other tools I learned how to use is Astrometry.net which can do something called plate solving, taking an image and finding where in the sky it is a view of. Here is the results of plate solving using one of the images used to create the shot above. I find this raw, astrometrically-labeled view an interesting alternative version of my night's labors since the comet (though not green) stands out a bit more.

The three dots and labels represent stars in the constellation
Camelopardalis identified using plate solving on astrometry.net

Anyway, the next time I am shooting a dim fuzzy (hopefully without the Moon up and away from city light pollution), I'll have had some practice and expect to be able to produce much better results. 

Stay tuned...

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