H-alpha activity - H-alfa number

In the period from August 2024 to March 2026, 52 H-alpha observations were carried out using a Sol’Ex spectroheliograph on a TLAPO60/360 and later a TLAPO80/480. Processing via INTI results in superior resolution, meaning the calculated prominence relative number (Rp = 10H + E) is systematically higher than the VdS reference. This is reflected in a k-value of 0.76 with a strong correlation (R2 = 0.88). Furthermore, the data confirm the time-lag effect of the chromosphere: the H-alpha prominence maximum occurs later than the sunspot maximum in the photosphere. This is logically explained by the fact that prominences are often residual phenomena of active regions that are already decaying underneath. The methodology used follows the standard from "Die Sonne beobachten" by Reinsch and Völker.

Determination of the H-alpha Relative Number for the solar limb (Rp or RHa)
The formula is defined as follows (1)

Rp or RHa = 10 H + E

With:
Rp or RHa: the H-alpha relative number
H (Herde): the number of activity centers on the solar limb
E (Einzelerscheinungen): the number of individual limb phenomena, individual phenomena such as separate prominences or limb flares.

(1) Die Sonne beobachten - Reinsch, Beck, Hilbrecht and Volker

Conclusion:
My observations follow those of VdS and Kanzelhohe.
My observations are systematically higher, which may indicate a difference in equipment resolution, cf. traditional H-alpha versus Sol’Ex.
The k-value is 0.76 with a reliability (R2) of 0.88.
Observations confirm the "time-lag" effect of the H-alpha maximum relative to the sunspot number. This is logically consistent, given that sunspots occur in the photosphere and prominences in the chromosphere.

Lecture by Steven Goderis on micrometeorites

Lecture by Professor Steven Goderis at the annual VVS meeting in Brussels (Grimbergen MIRA). 

Professor Steven Goderis and his research team at the Vrije Universiteit Brussel employ advanced geochemical techniques to unlock the secrets hidden within microscopic space dust recovered from both the Antarctic ice and ancient geological strata. 

By conducting precise measurements of oxygen isotopes and identifying specific minerals like chromium-rich spinels, they can accurately trace the origin of these particles back to different types of primitive asteroids. A crucial part of their work involves analyzing the concentration of these micrometeorites within different rock layers, as the fluctuating numbers of these cosmic grains provide a direct record of massive impact events in Earth’s past. These sedimentary archives allow scientists to reconstruct the flux of extraterrestrial matter over millions of years and understand how the chemical composition of our solar system has evolved. Beyond identifying their source, the team examines the chemical alteration of these particles to determine past CO2 levels and atmospheric conditions during their high-speed entry into our planet's orbit. Furthermore, studying the magnetic properties trapped within these tiny grains provides a rare glimpse into the strength and orientation of ancient magnetic fields that shaped the early solar system. By combining these diverse analytical approaches, Goderis continues to push the boundaries of planetary science, using the smallest particles to answer the biggest questions about our cosmic history.

Micrometeorites

Selfie with Steven Goderis and in the back my friend Jean-Marie :)

Lecture Code Rood by Toon Verlinden

Together with colleague Walter and Philip, I attended a lecture by Toon Verlinden of his book "Code Rood" or Code Red.

In the book Code Red, Toon Verlinden analyzes the vulnerability of our modern civilization by linking four catastrophic scenarios to their historical predecessors. He uses the 1815 eruption of Mount Tambora as a chilling example of a supervolcano; it caused a year without a summer and global famine at the time, reminding us of the fragility of our current food chain. Regarding the danger of asteroids, he points to the 1908 Tunguska explosion, where a relatively small fragment wiped out thousands of square kilometers of forest, to demonstrate why we are now developing missions like DART to prevent impacts with precision missiles.

Verlinden also warns of a repeat of the 1859 Carrington Event, a solar storm that merely caused telegraph lines to spark back then, but today would completely cripple our power grid and the internet. Finally, he draws lessons from the devastating 1918 Spanish Flu to emphasize the necessity of rapid vaccine development and global surveillance against new pandemics. By analyzing these destructive moments from the past, Verlinden shows that our modern technology is not only a source of vulnerability but also offers our only real chance to survive a subsequent global disaster.

I bough his book back in 2024 and beside signing my book, a selfie with author was made.

Near occultation of SAO77121 by the Moon on March 24, 2026

Last Monday (March 24), I was located just north of the graze line for the lunar occultation of star SAO77121. My colleague Bart from Helios had alerted us, allowing me to track the event. As Bart predicted, I was in the area where the star was not occulted. My colleague Lieven also observed the event; he was positioned just south of the graze line and saw the star narrowly escape occultation as well.

Timing UT21h34

Setting: Star Adventurer GTI with Nikon D7500 and 200mm lens

Conditions: Transparency good and Seeing moderate. 

Sunspot AR4392 March 22

 

Inverted image of H-alpha spectrum of the Sun from last Sunday March 22, 2026. Crop from AR4392.

Picture made using SolEx with ASI678MM on TLAPO80/480.

Halo 360°

Capturing a very bright 360° Halo around the Sun.

Coronal Hole and Sol'Ex images March 22

My Sol'Ex was used to capture the HeD3 line and after editing is was possible to bring forward the current coronal hole of the Sun. A comparison was made with SDO/AIA 211A and GOES19 195A. All in all it's not most beautiful picture but still I could capture the coronal hole. For sure I will try this again when a more deligned coronal hole shows up.

The day started with some bad seeing but during noon time seeing became better. I made time to adjust the Sol'Ex and was able to get sharp images in all captured wavelenghts.
Tilt was corrected with some very good results: 0,1° deviation... not bad at all. The most suffer from dust on the slit. Yesterday I did some cleaning, but not enough it seems.