Cédric Champeau
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melix.champeau.me
Cédric Champeau
@melix.champeau.me
890 followers 240 following 610 posts
He/Him. Software Engineer at #OracleLabs, formerly #Gradle. Amateur astronomer. Author of #JSolEx (solar image processing for spectroheliographs). Opinions are my own.
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melix.champeau.me
Avant 2024, personne n'utilisait le terme "narcotrafic". On utilisait "trafic de drogue". Il ne fait aucun doute que le changement correspond aussi à une volonté politique, celle-là même qui veut nous imposer une vision où l'insécurité est partout. Effrayer la population en changeant les mots.
February 12, 2026 at 10:14 AM
melix.champeau.me
Was super lucky to visit the CERN CMS experiment today! Tomorrow I will give my presentation about JSol'Ex at Voxxed Days, very exciting!
A representation of the main CMS detector The detector "brain", where data is processed real time to decide whether an event is worth recording
February 9, 2026 at 9:09 PM
melix.champeau.me
Measuring solar differential velocity with a spectroheliograph, right on time for Voxxed Days CERN! melix.github.io/blog/2026/02...

#jsolex #spectroscopy
A couple of graphs showing the velocity of the solar plasma, in km/s and degrees/day.
February 5, 2026 at 11:17 PM
melix.champeau.me
I will have the great honor to give a talk at Voxxed Days CERN on February 10th, about #JSolEx, the solar image processing software I wrote for spectroheliographs! If you are curious about solar physics, this is an opportunity to learn!
Conference speaker card. Name of the speaker: Cédric Champeau. Conference track : Mind the Geek Beginner level. JSol'Ex : solar image processing in Java Date: 10th February 2026 cern.voxxeddays.ch
January 23, 2026 at 9:34 AM
melix.champeau.me
The Flaming Star Nebula, mosaic of 2 panels.

Details on my Mastodon account: mastodon.xyz/@melix/11581...
A large field view of the flaming star nebula, also known as IC 405.
December 31, 2025 at 9:18 AM
melix.champeau.me
I am mind blown. I asked Claude to port Ratatui to Java, using Gradle, create a demo app and compile it to a native binary. It took 20 minutes. Here's the demo (this is a native binary compiled using GraalVM using the official native build tools plugin). 🫳🎤

/cc @glaforge.dev @maxandersen.xam.dk
December 19, 2025 at 4:18 PM
melix.champeau.me
And here you get the result of stacking. The first image is with classic processing, the second one has unsharp masking and proms enhancement. All this was obtained without use of other software, because I'm lazy and I like automation offered by JSol'Ex scripts :)
An H-alpha image of the sun, stack of 6 images processed in JSol'Ex. An improved image of the sun in H-alpha, showing more details thanks to unsharp mask.
December 14, 2025 at 8:06 PM
melix.champeau.me
I often see that folks use AS! to stack their SHG images. However, the algorithm in JSol'Ex is very capable. Here's an example with 6 images from today. In the animation, on the left, you can see the images "distorted" by turbulence. On the right, the corrected versions by JSol'Ex.
December 14, 2025 at 8:06 PM
melix.champeau.me
JSol'Ex 4.4 is out! Adds a number of 3d visualizations, including 3d projection of your images, 4d spectral cube and a volumetric rendering of the solar tomography!

Download it at melix.github.io/astro4j/late...

#JSolEx #solar #science
a 3d visualization of the spectral profile a 3d visualization of the spectral profile at a particular position on the slit A 3d view of the intensity of the spectrum, for a particular wavelength, on the solar disk Spherical tomograph of the sun, capture of a 3d rendering
December 14, 2025 at 4:16 PM
melix.champeau.me
New release of JSol'Ex coming today if everything goes well! A glimpse at what you'll be able to do...
December 14, 2025 at 11:58 AM
melix.champeau.me
Sur cette image inversée, on distingue en foncé les régions actives. Les "nuages" blancs sont des filaments solaires, qui ne sont ni plus ni moins que des protubérances vues "de face".

Le tout traité avec mon soft JSol'Ex 4.3 !
Sur cette image inversée, on distingue en foncé les régions actives. Les "nuages" blancs sont des filaments solaires, qui ne sont ni plus ni moins que des protubérances vues "de face".
December 3, 2025 at 3:36 PM
melix.champeau.me
Au même moment, une superbe éruption a eu lieu au Nord-Ouest. Une version Doppler de l'image permet de visualiser les vitesses impliquées, énormes (elle s'est déployée sur des centaines de milliers de km en quelques minutes).
Large solar eruption A virtual eclipse image, showing on the top-right a large blue region which corresponds to a massive eruption on the sun.
December 3, 2025 at 3:36 PM
melix.champeau.me
En ce moment, un groupe d'énormes taches solaires nous fait face. Ce midi, malgré la météo capricieuse, j'ai pu l'imager. C'est stupéfiant à voir : on peut visualiser l'effet du champ magnétique autour de ces taches. C'est un peu l'expérience de la limaille de fer, mais à l'échelle d'une étoile.
The sun on December 3, 2025. A giant group of sunspots is visible on the South-East (bottom left). The region is surrounded with line patterns which recall the iron filings experiment. Close up view of the active regions group. The dark round spots are roughly the size of Earth.
December 3, 2025 at 3:36 PM
melix.champeau.me
Sortie de JSol'Ex 4.3.0 avec pas mal d'améliorations (qualité du stacking, performances améliorées, nouvelles fonctions de scripting, ...). J'en ai profité pour ajouter un script qui permet de générer une tomographie solaire.

melix.github.io/astro4j/late...
Une tomographie solaire, qui permet, via de fausses couleurs, de refléter l'altitude de différentes régions de la chromosphère (en vert, plus profond, en rouge plus élevé, les filaments en pourpre).
December 1, 2025 at 10:50 PM
melix.champeau.me
Again nice prominences today on the Sun! Captured with an SHG 700 and processed/stacked using JSol'Ex!

#solar #astrophotography
Processed image of the sun in H-alpha An inverted version of the image in H-alpha. An image at the continuum around H-alpha (3Å) A Doppler image of the sun. A flare is visible on the right (West)
October 14, 2025 at 8:14 PM
melix.champeau.me
The sun captured in H-alpha late afternoon. Just had a few minutes so it's a stack of 5 images captured with the SHG 700 and entirely processed with JSol'Ex. The Doppler image shows interesting regions with high velocities! The active regions crop even shows Ellerman bombs! #solar #astronomy
The sun in H-alpha The sun in the continuum around H-alpha A Doppler image showing high velocities (the blue patch) A close up on active regions. Small white hot points are Ellerman bombs.
August 31, 2025 at 8:33 PM
melix.champeau.me
Right. Basically in my mind, you get gaussians. During the day, gaussian to the peak under ideal condition, and during the year, gaussian at peak month. See actual graphs from here.
Comparison of total production during the year Production during sunny day Production during average day (clouds and sun alternation) in summer
August 30, 2025 at 7:32 AM
melix.champeau.me
Same exists in Java
August 28, 2025 at 2:51 PM
melix.champeau.me
La binarisation typique de Trump, la simplification du vocabulaire (les méchants d'un côté, les gentils de l'autre) dans la bouche de Retailleau. Flippant notre époque.
CNEWS. "Il y a d'un côté la France des héros et de l'autre la France des salauds". Bruno Retailleau
July 25, 2025 at 6:52 AM
melix.champeau.me
Par ailleurs l'argument ne tient même pas la route de manière factuelle, lol.
Extrait du site de Nutella: "Nos noisettes proviennent principalement de Turquie, d'Italie et du Chili".
July 22, 2025 at 9:13 AM
melix.champeau.me
Last image before I pack everything. Helium D3 line.
An image of the sun, showing the Helium D3
June 20, 2025 at 8:12 AM
melix.champeau.me
An image of the sun captured from my backyards this morning, under good conditions. All processed with #JSolEx. It also automatically detected a couple of Ellerman Bombs. Science is fun! This afternoon I'm heading to Baron, Oise, in France, for JASON to meet with other solar observers!
An image of the sun in H-alpha Inverse version of the sun in H-alpha An image of the spectrum, showing an Ellerman Bomb An image of the spectrum, showing an Ellerman Bomb
June 20, 2025 at 7:06 AM
melix.champeau.me
On est d'accord qu'il y a 20 ans, des "tirs de mortier" on appelait ça des pétards ? Dans ma tête, un mortier c'est ça. Pas vraiment la même chose. A quel moment on a basculé ?
Un mortier de 120mm. Source : https://fr.m.wikipedia.org/wiki/40e_r%C3%A9giment_d%27artillerie
June 8, 2025 at 10:28 AM
melix.champeau.me
Le sosie de @sebi2706.bsky.social joue au #futuroscope
Groupe la boutik
April 20, 2025 at 9:43 AM
melix.champeau.me
Fascist attack against the Gnome project. Press release from Solidaires Informatique.
Friday, March 14, 2025, the GNOME free software platform community project was subject to a spam campaign on one of its public chat rooms. Pedocriminal content, photos of tortured animals and transmisogynistic messages were sent in mass by accounts taking the name of a well-known pro-trump fascist from Free Software communities. At the heart of this attack, violent messages essentializing trans women to mutilated bodies. Why was the GNOME project targeted? Because it defends values of inclusion and works actively to put them in place since a long time, through its code of conduct and involvement in programs such as Outreachy. Numerous members of the GNOME community and beyond have personally received these messages exposing them to violent and criminal content, including members of Solidaires Informatique. These conversation channels are a key tool for project workers and community members. Their goal is not only to hurt the most minoritized persons in the community, but to isolate them and exclude them from free software projects. It is not for the minoritized to leave these spaces but for extreme right-wing activists. It is worth noting the lack of moderation tools integrated into the core of the used messaging system, and the failure of third-party antispam tools put in place, we must no longer accept that tech-bros design communication tools without taking into account the advanced means of moderation constantly demanded by the most minoritized communities. But if the moderation tools have failed, let's not forget that the heart of the issue is the domination systems, racism, transphobia, misogyny and ableism which, crystallized in fascism, are at the heart of this attack. Let's protect the workers, let's protect our communities, let's build truly inclusive communication commons and repel fascism, as long as necessary
March 20, 2025 at 12:36 PM