I imaged two helium suns, at 5875.6Å the good old He I D3, together with another He I at 7065.2Å. In the D3, the signal is both stronger and of shorter wavelength, and also not at the very extreme of what the device can do, so there are more details.
He I at 7065.2Å
He I D3
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.
because google is no longer our friend when it comes to finding stuff
Solar spectrum, with tellurics https://hs5000.vo.aip.de/
SOLAR-ISS: A new reference spectrum based on SOLAR/SOLSPEC observations https://www.aanda.org/articles/aa/pdf/2018/03/aa31316-17.pdf
GOES X-Ray Flux https://www.swpc.noaa.gov/products/goes-x-ray-flux
Infrared Helium Sun: https://iopscience.iop.org/article/10.1088/1674-4527/ad37f4/pdf
Databases: https://data.nas.nasa.gov/helio/portals/solarflares/datasources.html
Flares and stuff: https://www.lmsal.com/isolsearch
Flare prediction forecast https://www.solarmonitor.org/forecast.php
Liege https://fermi.jhuapl.edu/liege/s08_0085.html
On 2025-06-16, at around 0936Z there was a bright flare visible in both Na D1 and Na D2, but also in He I D3 as a bright flash. 27 scans were recorded between 0856Z and 0940Z, with the last couple having the flare. The presented disk image is a composition of stacks, one stack of the disk without the flare, and another stack that shows the flare (motion blurred over a few minutes). Curious dopplers are also present in the raw, as sample frames from the raw scan show.
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.
Ever tried posting a link under a youtube video? It may get auto-deleted, no matter if it is on topic. Tried talking about how to find the on-topic resource, to avoid deletion? Also gets deleted. What we get instead is AI-slop upon AI-slop and a control of the narrative, like those not really on youtube never even existed.
Just fuck that.
Google is not your friend.
I recorded 30 scans of the Sun, using the SHG 700 with a 678MM camera.
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).
I used my solex setup to image the singly ionized iron right next to the forbidden oxygen. The signal is strong there. I cleaned up the image to remove most of the artefacts. Stack of 17 scans. 2025-04-21.
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…)
