I imaged the Sun in the neutral Helium line at 7065.2 Angstrom (706.52 nm), on 2025-07-20. The weather was unfavorable with passing clouds and varying seeing, so between 0911 and 1033 UT, a bit after local noon, I recorded and finally kept 19 scans.

I ran a few searches on the internet. Just like with the solar disk in Fe II 5018.45Å, with prominences and all, this may well be the first amateur spectroheliogram of the Sun in this wavelength, and probably the first ever to be processed to reveal these details.

It was a challenge to find this line, but among others, the flash spectrum came to my help.

I used a 80/540 refractor, an in-cone band pass 642 IR filter as the energy rejection filter, and the ML Astro SHG700, with the cooled 678MM camera. Image processing with JSolEx, my own scripts.

More data is needed to confirm this, but at a first glance, this line at 7065, just like the He I D3, appears to reflect features from the corona.

(tovább…)

A stack of 40 scans obtained with ML Astro’s SHG 700 spectroheliograph.

A stack of 16 scans obtained with ML Astro’s SHG 700 spectroheliograph.

Using the ML Astro SHG 700 (third batch) spectroheliograph, on a 80/540 refractor, ASI 678MM camera, I recorded seven scans of the Sun, in the singly ionized iron line, Fe II 5018.45Å.

This is what I got after getting rid of the artefacts and amplifying a bit the already strong signal (way stronger than He I D3).

singly ionized Barium, Ba II at 6141.73Å

I scanned the Sun into a cube, containing the Ba II line at 6141.73Å which, like we’ve seen with ionized metals before, turn the active regions dark, instead of letting them shine against a darker photosphere. The atmosphere was remarkably calm on 2025-04-21, and further, the disks were anti-jagged by an experimental feature in JSolEx. (tovább…)