On 2026-09-20, I observed the Sun in O I 7772. I applied the same processing, applied an artificial flat to remove most artefacts. The two frames show considerable changes in the patterns shown by oxygen, while others rotate quietly together with the Sun.

The two frames are centered around UT 0800 and UT 1230, each frame is a stack of dozens of scans (around an hour).

As a bonus, the filament to the right of the disk center, is also obvious.

I used a modified Sol’Ex spectroheliograph, ML Astro Filter, EO 1800 gr/mm grating, and EO 775/25 OD4 bandpass filter, attached to a 72/430 refractor.

I observed the Sun in multiple wavelengths, Hα, He I 10830, O I 7772, and the disk center filament shows up rather obviously in the processed oxygen data.

I also tried hacking the Challenger Deep instrument, ultimately failing to improve its performance. The best addition proved to be yet another piece of black (both visually and IR) duct tape, covering a rogue area of the grating that’s perhaps rotated beyond its optimal angle.

O I 7772, false color, amplified via continuum subtraction, stack of data from multiple scans

O I 7772, amplified via continuum subtraction, stack of data from multiple scans

single scan Ha

single scan continuum around Ha

Previously, as described in Smudges in Oxygen, O I 7772 I hinted at the fact that smudges in oxygen are usually accompanied by bright smoldering in EUV, and that the difference between AIA 1600 / AIA 1700 is a potentially good indicator of where to expect smudges.

In 2029-09-15, I collected data where a prominent smudge appears in oxygen, without anything outstanding in other wavelength. The smudge persisted for several hours, during which the area in question didn’t flare.

The smudge is the dark „spot” at around 9 o’clock, corresponding to a plage and filament in Ha.

(tovább…)

Stacking 12 scans, through continuum subtraction and further processing, I managed to reveal some really subtle details on the Sun, clearly showing filaments in Oxygen. Somewhat ironically, on this day, there were no flares, no smudges and no bright prominences, to add to the repertoire of the image presented here. I included AIA 1600, GONG and AIA/SUVI 304 for reference.

I consider it settled: there are filaments in oxygen, in O I 7772, on the disk of the Sun, and a Sol’Ex derivative amateur spectroheliograph can observe them.

(tovább…)

Today I managed to gather the best data so far in support of having visible filaments in oxygen, over the solar disk. Nota bene, they have to be dark and dense filaments, as seen in hydrogen alpha, but they are there. A nice addition to the smudges.

I used the a customized SolEx spectroheliograph, with an 1800 ln/mm holographic grating, an EO in-cone prefilter centered to 775nm, ML Astro’s slit, and Altair Astro’s IMX 678M camera implementation. The assembly was mounted to a 72/430 doublet.

Because oxygen darkens over plages, filament observation is extra hard. But blink comparing against AIA 1600 and the iron from below the oxygen triplet reveals no candidate plages.

The flare’s dark imprint is at the bottom left corner of the „bright” sunspot, on this continuum subtracted image

On 2026-06-24, I observed the flare that occurred and peaked at around 0710Z, in the neutral carbon lines C I 9095 and C I 9112. Both darken subtly when the flare is present, just like oxygen does. But unlike with oxygen, which has an obvious chromosphere, I failed so far to identify anything meaningful for these carbon lines.

Also much like the oxygen, sunspots show excess light, while plages show a deficit, the disk being overall rather dull in comparison to neighboring continuum lines.

An interesting factor when processing these pictures is that the reference lines land on tellurics, and hence the solar lines doppler visibly as we scan from solar west to east.

The flare is at the big „bright” sunspot, bottom left.

(tovább…)

I observed the Sun in multiple wavelengths, recording spectroheliograms in Sr II 4077, Fe I 4383, and spectra in the UV — no disks, because of the clouds. Always the mandatory clouds.

Fe I 4383

If I identified the lines correctly

Sr II 4077 delta1

Sr II 4077 division

Sr II 4077 delta2

Sr II 4077 continuum at 11 pixels distance

Sr II 4077 line reconstruction