First Calcium K Sun in terrible conditions! 12-03-20

[ArmyAirForce]

Calcium K Line and White Light Sun - 12-03-20

It was a blue sky this morning, nice and sunny.....and blowing a monster gale, but I had new astro gear to test, so wasn't going to let that put me off!!

So armed with my Evo 80ED scope, the Baader ND3.8 solar filter, Baader Calcium K Line filter and ASI120MM-S camera, I ventured outside in the hope my observatory was where I left it! It's four years this week since I built it.

I wasn't expecting fantastic results for several reasons. It was my first try at CaK imaging, the Sun wasn't that high, it was blowing a gale and the seeing was terrible due to the jetstream so the UV wasn't going to get though cleanly. However, I had a 45 minute session starting about 09:25hrs.

So the first solar capture is a five pane mosaic in false colour in the Calcium K Line. This was shot at the native 600mm focal length.

A mono version of the same image follows.

The mono CaK image can be more easily compared to the third disc which was a White Light image with the Baader Solar Continuum Filter. This is also a five pane mosaic with the same camera, scope and ND3.8 solar filter. 

Two more close up images follow, shot through my TAL x2 barlow, giving 1200mm focal length.

 

Stacking for the full discs was 25% of 3,000 frames while the close ups were 25% of 5,000 frames. I normally use Gaussian-Linear wavelet settings for the Sun, Moon and planets, but found I could get better detail in UV with Default-Dyadic wavelet settings. Things may change with better seeing, but for now, I need to approach the processing slightly differently to my usual images.

So, it was only a quick test in very poor conditions, but it already shows that CaK can show much more detail than White Light. I'd considered getting my Ha scope out, but the conditions didn't make the effort worth while, so a session capturing Ha, CaK and WL will have to wait for another day. I'm looking forwards to better seeing and further Sun spots from the waking Solar Cycle 25.

[Pete Presland]

Nice set of images there.