Borges, the blind librarian, helping out to manually cull the results, and select which frames, if any, go to stacking. The fog/haze helped, but the clouds… didn’t.
2025-01-25-0805 2-Sun-Ha 2025.01.25. disk 0 00 pipp lapl2 ap12291 reg1 ps4 mono
2025-01-25-0805 2-Sun-Ha 2025.01.25. disk 0 00 pipp lapl2 ap12291 reg1 ps4 color
manual culling
On 2025-01-12, I imaged the Sun in He I D3. Using my scripts to extract the weak signal, I got able to show features otherwise characteristic of the corona. I stacked a total of 72 scans, spanning between 2025-01-12-0741Z and 2025-01-12-0933Z. Basically, I imaged the fingerprint of the giant coronal hole.
The Helium I D3 line, unless one knows exactly what to look for, is elusive to put it mildly. Hence the secret. And the poet, Attila JÓZSEF warned us: a titkokat ne lesd meg. So let’s take the spectroheliograph and image the Sun ostinatamente. 78 scans went into this image on 2024-11-02.
Using the spectroheliograph and the ~30nm wide sodium ERF filter, I imaged the Sun in the He I D3 spectral line. Recordings processed with JSol’Ex, and details enhanced by the script below. For the final images, about forty individual frames (reconstructed scans) were stacked.
Fun fact, the light triangle in the lower half of the image corresponds to a dark feature in the corona, as seen on the SDO AIA 211 image.
One day after the X1.8 flare, business as usual on the Sun. I collected 40 scans in the Helium I D3 line, spanning about 40 minutes — so if there were any small scale details to begin with, they are probably lost.
He I D3 enhanced, heavy wizardry
The Sun on 2024-09-13, around the CaH line, also touching Hydrogen epsilon. Pixel shifts range from -36 pixels (blue wing) to +40 pixels (red wing), meaning somewhere around -2..+2 Å in total, give or take.
I combined some spectroheliograph data with the etalon, Sol’Ex at 62/400 with Lunt CaK B1800 at 102/1100.
The Sun in Helium D3, He I D3
This really feels like standing on the shoulders of giants. I got my Sol’Ex spectroheliograph, and started using it with INTI and JSol’Ex (links below). Long story short, while the Sol’Ex in the plastic feels like a toy, it bends, sags and kinks and twists and vibrates and all, I find it an excellent introduction, and beyond, to solargraphy and spectroscopy. The software? It blows my mind.
Solar disk in Altair Astro’s 3nm CaK Ultra filter, enhanced contrast
I got a new filter to pudding-test: Altair Astro’s 3nm Calcium K Ultra, stated to have 3nm FWHM and a very high transmission. Let’s see how it performs.
Before we jump in, let me also present some information I compiled along the way, and some theory and links fellow amateur astronomers may find useful.
Important note: this article is not sponsored by the vendor, and the vendor has not influenced the conclusions presented below in any way.
