O I 7772 (~) continuum, showing excess light on spots and shadows on plages

I observed the Sun in two oxygen lines, the O I 7772 and O I 8446, with the modified Sol’Ex (1800 gr/mm grating, band pass filters etc, 42/400 refractor). Unlike 7772 (the triplet), the 8446 (close doublet) doesn’t light up at the limb, as chromosphere. Regardless, I observed and processed the images. For λ7772, I have a full aperture etalon (CWL 775nm, FWHM 25NM, OD4 blocking), but only relatively wide bandpass filter(s) for λ8446, so parasite light is somewhat of an issue. Still, there is an interesting dark feature present in both observations, at around 4 o’clock, close to the edge.

(tovább…)

O I 7772 divided by a nearby continuum, stretched. Showing prominences, excess light on sunspots, darkening on active regions, and a dark shadow where the flare occurred at around 2026-02-03 07:49Z

Active region 4366 shows quite the flares. I observed the Sun at around local noon, at the infrared oxygen triplet at 777nm, focusing on the O I 7772 line. Below I present data from two scans, UT 2026-02-03-0727 with little indication of flaring, and UT 2026-02-03-0749 with clear signs of something going on.

I see what seems to be a clear indication of flaring: regions in oxygen go darker when other wavelengths shine, somewhat like He I D3 does — albeit I’ve seen bright helium flares in both D3 and even in He I 5016 before. Instrument: the modified Sol’Ex spectroheliograph,  with the 1800 ln/mm grating, and a front mounted full aperture Edmund Optics filter, CWL 775nm FWHM 25nm OD4. With the refractor thus stopped down to about 46/400, I recorded a time series. General observing conditions were poor, with passing clouds and bad seeing.

Processing: reconstructing the disks of the wavelength and a chosen continuum, dividing and stretching the two, and various other scripts for other kinds of output.

(tovább…)

before, and during the flare. Hα for reference

Did I just record a solar flare, its imprint in some form, in the infrared oxygen triplet’s O I 7772 line? I think there is something in the data, I just don’t know what exactly.

Using a modified* Sol’Ex, I recorded the Sun at the infrared oxygen triplet, together with the neutral iron Fe I 7781. Passing clouds and some haze made the session less than ideal. The recordings have been reconstructed in JSolEx, and further processed with JSolEx’s ImageMath module.

The oxygen triplet lights up in an obvious manner near and beyond the disk edge, and prominences are visible after applying curves or subtracting a continuum from the disk at the wavelength. This is what I expected, based on what I read in the literature.

Between around 10:30Z-11:00Z, local time 12:30-13:00, there was a flare on the Sun, and for the second half of it, I recorded, still between the clouds.

blink compare: bad seeing and the clouds didn’t help

(tovább…)

Paschen Gamma (enhanced) Solar Disk

Using the purpose built spectroheliograph, with stacked filters of 1075nm/50nm and 1100nm/50nm, I observed the Paschen gamma line (λ 10938.1Å), hoping to extract Hydrogen-resembling disk details. Neither the seeing, nor the low winter Sun helped the observation, worsening the already challenging endeavor.  For this observation, I used the IMX 585MM camera, instead of the 678MM, hoping to get more photons per pixel, sacrificing some spectral resolution — mixed results.

Still, the image published here, with the signal enhanced, could well be the very first Paschen Gamma Solar Disk, bringing the details to life.

The line itself is much weaker than the He I D3, it is a nebulous blur on the spectrum on the disk center, and is dwarfed by He I 10830 in the flash spectrum. In this respect, it resembles the situation of the (Balmer) epsilon line, which is overwhelmed by the calcium valley, or that of the He I D3 which is somewhat subtly visible while scanning, and is fully revealed only through continuum subtraction.

(tovább…)

With a rather unusual setup, the SolEx coupled with the IMX 571 wielding Altair Astro 26C camera, I observed a bright solar flare at 2025-09-28 08:43Z (a longer time series actually) at to my surprise, the helium line also lit up. This is not a typical nor a recommended setup of the SolEx. I sacrificed spatial (either way, bad seeing) and spectral (…) resolution for bit depth.

With the Helium image, I cheated a bit: the perpetually changing thin clouds resulted in the helium wavelength’s disk center getting saturated from time to time, so data’s been taken from non-saturated takes, to fill that gap.

He I 5015, continuum-subtracted

Fe II 5018, CLAHE-enhanced signal

spectra, before and during