Supernumerary and double rainbows and a drone image of rainbow

Last week I could capture some special rainbows: double rainbows and supernumerary rainbows.

I took aswell a picture using my DJIO Neo2 drone.... really promising. 

Very rare 9° Halo

On June 11, 2026 I could capture a very rare halo. Beside the 22° Halo, there was aswell a 9° halo. I send my picture to Beglium Weather group  which confirmed the 9° halo. The 9° halo finds it's origin in pyramid chrystals. See aswell this website : https://www.meteoros.de/themen/halos/haloarten/ee31

Comparing MgI B2 and CaIIH line and magnetic canopy

When observing the sun through the MgI B2 line, we are looking at the absolute base of the solar atmosphere—specifically within the transition zone from the high photosphere to the low chromosphere (the temperature minimum) at an altitude of approximately 600 to 700 kilometers above the visible solar surface. At this specific height, the gas pressure is still relatively high, causing the churning gas to powerfully push the magnetic fields aside and tightly compress them along the edges of the giant supergranulation cells. As a result, a MgI B2  image reveals supergranulation as a sharp, thin, and geometric 'spiderweb' of bright magnetic lines, interspersed with relatively quiet, dark cell centers where the normal, smaller granulation of the photosphere still faintly shimmers through. This yields a pure and undistorted view that lays bare the exact roots and foundation of solar magnetism.

Comparing MgI B2  with CaII H.

When we compare these images with observations in the CaII H line, we ascend several floors up into the active chromosphere, reaching an altitude of 1,000 to 1,800 kilometers. Because the gas pressure drops exponentially at this great height, the crushing force that compressed the magnetic fields below completely vanishes. Consequently, the sharp, thin lines from the magnesium image transform into broad, fluffy, and cloud-like structures in the calcium image; the magnetic fields flare out in a funnel-like shape, forming the so-called magnetic canopy that partially drapes over the dark cell centers.

Furthermore, the entire texture of the sun changes completely: the crisp, geometric appearance of the magnesium line gives way to a chaotic and 'hairy' landscape in the calcium line, filled with fibrils (magnetic gas streams shooting upward like blades of grass) and bright flashes from acoustic shock waves. Finally, due to intense heating higher up in the chromosphere, active regions around sunspots light up as gigantic, brilliant magnetic clouds (plages) in the calcium line, whereas those very same regions remain highly compact and sharply bounded in the lower magnesium line.

Concretely, we see the emergence of supergranulation in Mg I B2, which then further develops and expands in CaII H. I  dived into my archives and reprocessed my images from December 28, 2025. The results clearly showcase the sharp, crisp definition of the supergranulation in MgI B2 versus the fluffy, chaotic magnetic field boundaries in CaII H. According to solar physics papers, the phenomena we observe in MgI B2 can only be explained if we assume they occur in an NLTE (Non-Local Thermodynamic Equilibrium) environment. This stands in contrast to LTE (Local Thermodynamic Equilibrium), which is typically much easier to calculate and model.

Setup & Processing Details:

Equipment: SOLEX by James R with a 2nd Gen Slit, mounted on an AZ-EQ6, using an ASI678MM camera.

Capture & Initial Processing: Captured in SharpCap and processed via Inti.

MgI B2 Image: Created from a stack of 3 exposures using AstroSurface, with final editing done in IMPPG and Photoshop CS4.

CaII H Image: A single-exposure capture, processed and enhanced using Photoshop CS4 and Topaz DeNoise AI.

Reversed images

Sodium tail of Mercury

Not a good sky at all but good enough to do a test to catch the sodium tail of Mercury.

Set up:

- AZEQ6 Mount

- Sigma 18-35 f/1.8 lens

- Sodium Filter

- ASI2600MC

Software : SharpCap 4

Stacking : AstroSurface and editing CS4

So, weather was not good with poor transparency resulting in no tail at all. Next time focal point will be increased aswell.

Sol'Ex Pro fine adjustments

The Sol'Ex Pro version has an adjustment ring for the collimator block. It works better then version 1 but still it's difficult to get a sharp image. Christian Buil provided an exact number for the distance of the collimator block: 88,5mm. This setting is explained in below.  Be aware this distance is for H-Alpha. I asked the question about CaII H/K line and this was Christian's response:

Regarding a question I was asked: the 88.5 mm value I recommend is optimal for H-alpha and, more generally, for the visible spectrum. For the Ca II H & K lines, it is preferable to aim for 88.8 mm. This corresponds to about 0.3 turn of the adjustment ring when switching from H-alpha to Ca II directly on the telescope, without having to disassemble the instrument.


So te difference between H-alpha and CaII H/K is according to Christian 0,3mm. 

I''m using the distance of the opening in the collimator block to adjust for H-alpha and CaII H/K.

As a base this is about 6,24mm and will be 6,54mm for CaII H/K

Sun with SolarMaxIII Double Stack and 678MM

The Sun this afternoon with SolarMaxIII Double Stacked and first time using my ASI678MM. I used a reducer x0,5 and made flats using SharpCap. Also the seeing monitor of SharpCap was used to capture only the 2% best images. Exposure time 0,294ms and 2000 frames. AstroSurface completed stacking and keeping 1000 frames for editing.

The sun was very active with a relative H-alpha number of 184.

Sun with Coronado SolarMaxIII DS

It is already the sixth consecutive day with clear skies and temperatures are climbing above 30°C. Therefore, I absolutely wanted to observe the sun, but given my surgery, this was not possible. Today went better and I asked the kids to set up the telescope with my Coronado SolarMaxIII DS BF15. The sun is still quite active with several sunspots and prominences. According to my observation, the Rp or relative H-alpha prominence number was 131.

Pictures made with my IPhone 16 - no editing.

Comet C/2025 R3 PANSTARRS published in Magazine Heelal

My observation of Comet C/2025 R3 PANSTARRS is published in magazine Heelal of June 2026.

"Perhaps the observer who was the last to record PANSTARRS from our region was Pascal Hilkens. On Sunday morning, April 19, he set his alarm for 04:30 AM local time “to then go by bicycle to the hinterland in search of a dark sky. At a distance of 5 km from Nieuwpoort-aan-Zee, I found a nice location with a full view of the east. There were still some light domes and the horizon had some high cloud cover. From 5:25 AM to 5:55 AM, I took several photos with my Nikon D7500 with a Nikkor 18-200 mm lens, but visually I could not observe the comet.”

Very cool to have my observation published. My images could not be published as the details were to small. 

Solex Image and fall of Solex

This morning I made two images of the Sun using my Sol'Ex by James R. Unfortunately I walked into the Sol'Ex which fell on the ground with some damage. Luckely my camera and the optics are fine. Only damage to 6 3D parts.

Setting: Sol'Ex, ASI678MM with Herschel Wedge

Software: SharpCap, Inti, CS4

Explaining the Sodium tail of Mercury 16 days before or after perihelion.

The phenomenon behind the visibility of Mercury's sodium tail is a fascinating interplay of orbital mechanics and light. While Mercury reaches its maximum orbital velocity of about 59 km/s at perihelion, its radial velocity—the speed at which it moves directly away from the Sun—is nearly 0 km/s at that exact moment. However, due to its highly eccentric orbit, the planet begins to recede rapidly after passing this point. Approximately sixteen days post-perihelion, this radial velocity reaches an optimal peak of over 10 km/s.

This radial motion is critical because of the "Sodium Trap." The Sun's atmosphere contains sodium that absorbs light at specific wavelengths, particularly the D-lines (around 589 nm), creating a deep "dark gap" or absorption line in the solar spectrum. At perihelion, the sodium in Mercury's exosphere is aligned with this dark gap. Without sufficient photon flux, the atoms lack the radiation pressure needed to be pushed into a visible tail.

The sodium atoms are supplied to the exosphere by several distinct processes:

Thermal Desorption: Extreme daytime temperatures of 430 °C cause sodium to evaporate from the surface.

Solar Wind Sputtering: High-energy particles from the sun strike the surface at an atomic level, knocking individual sodium atoms loose.

Micrometeorite Impacts: Tiny dust particles strike the surface, causing mini-explosions that throw material into space.

Think of a surfer paddling away from a wave. If the surfer stays still relative to the wave's source, the frequency remains the same. But by paddling away at high radial speed, the frequency of the incoming waves of light shifts. This Doppler effect causes a redshift in the solar light reaching Mercury. Sixteen days after perihelion, the shift is large enough (about 0.02 nm) that the sodium atoms move out of the solar absorption shadow and receive approximately 40% more light.

This increased photon flux provides the physical momentum "kick" needed to accelerate the atoms away from the planet, while simultaneously causing them to glow through fluorescence. This specific timing is why observers look for windows sixteen days after perihelion—such as June 3, 2026 or November 26, 2026—to capture the tail at its most brilliant.

Het fenomeen achter de zichtbaarheid van de natriumstaart van Mercurius is een fascinerend samenspel tussen baanmechanica en licht. Hoewel Mercurius zijn maximale baansnelheid van ongeveer 59 km/s bereikt tijdens het perihelium, is de radiale snelheid—de snelheid waarmee hij direct van de zon af beweegt—op dat exacte moment nagenoeg 0 km/s. Vanwege zijn zeer excentrische baan begint de planeet echter snel afstand te nemen zodra hij dit punt passeert. Ongeveer zestien dagen na het perihelium bereikt deze radiale snelheid een optimaal hoogtepunt van meer dan 10 km/s.

Deze radiale beweging is cruciaal vanwege de zogenaamde "natrium-val". De atmosfeer van de zon bevat natrium dat licht absorbeert op specifieke golflengten, met name de D-lijnen (rond 589 nm), wat een diep "donker gat" of een absorptielijn in het zonnespectrum veroorzaakt. Tijdens het perihelium bevindt het natrium in de exosfeer van Mercurius zich precies in dit donkere gat. Zonder voldoende toevoer van fotonen ontbreekt het de atomen aan de stralingsdruk die nodig is om ze weg te duwen en een zichtbare staart te vormen.

De natriumatomen worden aan de exosfeer geleverd door verschillende processen:

Thermische desorptie: Extreme dagtemperaturen van 430 °C zorgen ervoor dat natrium uit het oppervlak verdampt.

Sputtering door zonnewind: Energierijke deeltjes van de zon raken het oppervlak op atomair niveau en slaan individuele natriumatomen los.

Inslagen van micrometeorieten: Minuscule stofdeeltjes raken het oppervlak en veroorzaken mini-explosies die materie de ruimte in slingeren.

Stel je een surfer voor die wegpeddelt van een golf. Als de surfer stil blijft liggen ten opzichte van de bron van de golf, blijft de frequentie hetzelfde. Maar door met een hoge radiale snelheid weg te paddelen, verschuift de frequentie van de inkomende "lichtgolven". Dit Doppler-effect veroorzaakt een roodverschuiving in het zonlicht dat Mercurius bereikt. Zestien dagen na het perihelium is deze verschuiving groot genoeg (ongeveer 0,02 nm) zodat de natriumatomen uit de "schaduw" van de zonne-absorptie stappen en ongeveer 40% meer licht ontvangen.

Deze verhoogde fotonenstroom geeft de fysieke "kick" die nodig is om de atomen van de planeet weg te versnellen, terwijl ze tegelijkertijd gaan gloeien door fluorescentie. Deze specifieke timing is de reden waarom waarnemers zoeken naar momenten zestien dagen na het perihelium—zoals op 3 juni of 26 november 2026 —om de staart op zijn helderst vast te leggen.

VVW Halo and Publication

Since end 2025 I'm a member of the whatsApp groep VVW Halo. The associated WhatsApp group is a private community for members of the Weather association VVW. It is used for real-time weather observations, such as reporting storms, lightning, or optical phenomena like halos and rainbows. The reportings are analysed and published in their monthly magazine Halo.

The first quarter results are published last month including my observations and pictures. Looking at the graphs, a halo could be seen in the mentioned period average every 3 days.

My first Meteorite Sikhote-Alin USSR 1947

The Sikhote-Alin meteorite fall remains one of the most spectacular events in modern astronomical history, occurring on the morning of February 12, 1947, in the Primorye region of Russia (USSR). Unlike many meteorite falls that occur over uninhabited oceans or deserts, this event was witnessed by numerous people who saw a fireball brighter than the sun descending over the Sikhote-Alin Mountains. The bolide entered the atmosphere at a high velocity and began to break apart under the immense pressure of the descent. The final explosion was so powerful that it was heard hundreds of kilometers away, leaving a thick smoke trail in the sky that persisted for several hours.

When the meteorite disintegrated, it created a massive debris field known as a strewn field, covering a significant area of the dense forest. The impact was violent enough to produce over a hundred craters, the largest of which measured twenty-six meters in diameter. Because the parent body was a massive iron meteorite, it did not simply burn up; instead, it showered the taiga with tons of iron fragments. Explorers and scientists who reached the site discovered a scene of total devastation, with shattered trees and jagged metal shards embedded in the ground.

Collectors generally distinguish between two types of specimens from this fall. The first type is the individual meteorite, which traveled through the atmosphere long enough to develop a smooth surface known as a fusion crust, often covered in thumbprint-like indentations called regmaglypts. These are prized for their aerodynamic appearance. The second type, which is frequently found at major events like the ATT fair in Essen, consists of shrapnel fragments. These are jagged, twisted pieces of iron that were torn apart by the force of the main explosion or upon impact with the frozen ground.

Owning a piece of Sikhote-Alin is special. The Sikhote-Alin meteorite is classified as an iron meteorite belonging to the meteorite group IIAB and with a coarse octahedrite structure. It is composed of approximately 93% iron, 5.9% nickel, 0.42% cobalt, 0.46% phosphorus and 0.28% sulfur, with trace amounts of germanium and iridium. Minerals present include taenite, plessite, troilite, chromite, kamacite and schreibersite 

When you hold a piece purchased at a specialized fair like the ATT in Essen, you are holding a fragment of a planetary core that formed billions of years ago, only to be violently delivered to Earth in a remote Russian forest less than a century ago. It serves as a tactile connection to the raw power of our solar system and a permanent reminder of the day the sky literally fell in eastern Siberia.

Aurora Flatfield ¨Panel

At the annual ATT Essen I purchased a second hand flatfield panel. The Aurora Flatfield Panel with a diameter of  315 mm and an 12V Inverter works perfect with my ASIair. 

This flatfield shield will serve to make flats. 

Supernova SN2026kid in NGC5907

NGC 5907 is spiral galaxy located in constellation Draco and about 46,5 million lightyears away from Eath. It's magnitude is 10.3 and is commonly called the Splinter Galaxy or Cat Scratch Galaxy.
On April 22, a supernova was detected in NGC5907; a supernova type II, and was noted as SN2026kid. This is the second supernova, the first one in 1940.


Capturing the supernova using TAL200K f/8.5 with ASI2600MC on May 1 and May 2. 

- Total integration time 2h40min (Lights 32x300s).

- Bias, Darks

- Flats using Aurora Flatfield Panel Flat315R with ASIAir. 

Processing with APP and editing using CS4 and DeNoise AI.

 

300.000 Visitors on my Blog. Thank You

 

Today my blog reached 300.000 visitors. Thank you for keep reading my blogposts.

100 days to Total Solar Eclipse August 12, 2026

 100 days to go to Total Solar Eclipse August 12, 2026.

Supernova type 2 SN2026kid in NGC5907

NGC 5907 is spiral galaxy located in constellation Draco and about 46,5 million lightyears away from Eath. It's magnitude is 10.3 and is commonly called the Splinter Galaxy or Cat Scratch Galaxy.

On April 22, a supernova was detected in NGC5907; a supernova type II, and was noted as SN2026kid. This is the second supernova, the first one in 1940.

I could image the supernova using TAL200K f/8.5 with ASI2600MC.

Polaralignment and Staralignment using SharpCap

Capturing with ASIAir Plus

Filter : Optolong L-Pro

Exposure : 10x300s (with guiding)

Software: SharpCap, ASIAir Plus, APP, DeNoise AI, CS4

Workproces astrophotography using ASIair Plus

 

My workprocess when using TAL200K with ASIair for deepsky imaging. 

44 Nysa in M44

This weekend, asteroid 44 Nysa could be observed when crossing M44. M44 or Beehevi Cluster, is a bright open star cluster.

Setting:

TLAPO80/480 with ASI2600MC.

Filter Optolong L-Pro

Exposure : 37x60s (FITS)

Software: SharpCap, ASTAP, CS4

The best fits files were stacked using ASTAP. Stacking was done both on stars as on 44 Nysa. 

Venus, Uranus & Pleiades

Venus, Uranus with Pleiades.

Venus, Moon and Pleiades

During my vacation in Nieuwpoort I could capture Venus, the Moon with Pleiades. I used my Nikon D7500 with Sigma 18-35mm f/1.8 lens.

Jef Ongena lecture on Georgens Lemaître

Jef Ongena's lecture on Georges Lemaître sheds a clear light on the origins of the Big Bang theory. He explains how the Belgian priest and astronomer was the first to realize that the universe is not static, but constantly expanding from a primeval atom. In doing so, Ongena corrects the historical narrative in which Edwin Hubble often receives all the credit for this discovery. During his presentation, he clarifies how Lemaître kept science and faith strictly separate to protect the integrity of both fields. The speaker further connects these historical insights with modern astronomical observations of cosmic background radiation. The result is a compelling account of intellectual courage and the Belgian contribution to our fundamental knowledge of the cosmos. Thanks to Ongena's accessible style, this complex subject becomes understandable for a broad audience. This ensures that Lemaître's legacy remains alive in contemporary scientific discussions about the beginning of everything.

Selfie with Jef Ongena

Some references:

The difference between f/1.8 and f/3.5

Since a couple of months I own a Sigma 18-35mm f/1.8 lens. I know this lens captures more light but how much more and what about comparing with my Nikon 18-200mm f/3.5-5.6 lens.

I captured the same scene with same settings:

- Nikon D7500

- Exposure time 1.3s

- ISO 800

The difference, which is significantly can be seen in the picture below.

The Sigma lens f/1.8 captures 4 time more light as my Nikon 18-200mm lens on 18mm f/3.5.

So f/numbers do matter :)

Comet C/2025 R3 (PanSTARRS)

It was a very early start this morning. I got up at 4:30 AM and hopped on my bike, heading inland in search of darker skies. About 4 km from the Nieuwpoort coast, I found a clear view of the eastern horizon. After setting up my gear, the waiting game for the comet to rise began. By 5:30 AM, an orange-red glow started to creep over the horizon.

I couldn't spot the comet with the naked eye, or even on my camera screen, so it was a bit of a gamble whether I’d captured it—especially with those high clouds lingering near the horizon. Back at the apartment, after some post-processing, I finally saw it: Comet C/2025 R3 (PanSTARRS). There’s even a small tail visible!

At the moment of capturing, the Comet was about 7° above the horizon.