Sun January 4th

A 5cm layer of snow and a perfect blue sky. Sol'Ex time :)
My SSM3 Seeing monitor registrated very good seeing with levels below 1 arcs with sometimes below 0,5arcs. I still have issues with my allignment of the spectral lines which are curved. Maybe I need to adjust the slit? 

Setting: TLAPO80/480 with Sol'Ex by James R and ASI678MM

2nd Gen slit and Herschel Wedge

Tilt <0,5° and Sx/Sy 1,15

SSM3 seeing Monitor via SharpCap

Software: SharpCap, Inti, JSol'Ex, CS4, DeNoise AI

ROS 2026 - Registration is open

The next Solar Observers’ Meeting (ROS) is scheduled for June 13–14, 2026, in Serbannes. Once again, the program will feature many instruments dedicated to solar observation in white light, calcium lines, and the H-alpha line for observing prominences, as well as the latest filter innovations. The Sol’Ex spectrograph will also be part of the event.

Registration is now open.

Nikon D7500 Shutter Count

 

My Nikon D7500 has currently 42472 clicks. According to Nikon, my camera can reach 150.000 clicks.

The count was made using  https://www.camerashuttercount.com/

Sun January 2nd

My first observation of the Sun this year.
Moderate conditions and settings of Sol'Ex not perfect, mainly the north side of the Sun.

Setting

Sol'Ex by James R, TLAPO80/480 with ASI678MM

Tilt < 0,1° Sx/Sy 1,04

2nd Gen slit and Herschel Wedge

Software: SharpCap, Inti, JSolex 4.4.2 and CS4

My picture of Comet C/2025 A6 Lemmon in Magazine Heelal

My image of Comet C/2025 A6 Lemmon is published in Magazine Heelal. This is my 35th contribution to this Astronomical magazine. 

 

Happy New Year 2026

 Happy Astronomical New Year 2026 with lots of clear skies.

My Astronomical & Blog statistics

My astronomical and blog statistics.

- Same blogposts as the last two years

- Increase visits and now above 240.000 visits

- My project "Herschel 400" is not progressing

- A total of 16 observation nights, which much better then last year and comparable with 2023. The focus is on a couple of objects and long exposure images made over more days; eg. Comet C/2025 A6 Lemmon and Bernard's Loop.

Bernard's Loop Sh2-276

After a first session on X-mas day and a failed second session, a third session was completed on December 28.

This third session was a combination of H-alpha and Optolong L-Pro; all of them 300s exposure time.

Using APP, all images are stacked, resulting in a total integration time of 4hours 25minutes.

Bernard's Loop and Sh2-264, Lambda Orionis Ring or Angelfish Nebula is good visible. I'm still doubting on the quality of the images. Hopefully I can add one more session to get up to 6h total integration time. 

Sun on December 28

The Sun on December 28, 2025. Interesting is the Magnesium Mg I B2 line with a small prominence.

Setting: Sol'Ex by James R, with 2nd Gen slit and Herschel Wedge

Software: SharpCap, Inti, JSol'Ex, CS4, DeNoise AI

Tilt < 0,2° Sx/Sy 1,1

 

Book "Gek op Natuurkunde"

Walter Lewin is a famous physicist and teacher, best known for his inspiring lectures on physics at MIT. He has a unique way of explaining complex ideas using clear demonstrations and a lot of enthusiasm. His passion for science has motivated millions of students around the world.

In his book Crazy About Physics, Walter Lewin shares his life story and his deep love for physics. The book combines personal experiences with explanations of physical phenomena, making science feel exciting and accessible. Through stories, experiments, and reflections, Lewin shows that physics is not just about formulas, but about curiosity, wonder, and understanding the universe.

You should buy Crazy About Physics because it makes physics exciting and easy to understand through real-life examples, stories, and experiments. Walter Lewin’s passion and engaging teaching style can inspire your curiosity and help you see physics as something fascinating rather than difficult.

Bernard's Loop Sh2-276

Bernard's Loop is identified as Sh2-276. Sh2 is the abrevation of Sharpless, a catalog of 313 H II regions (emission nebulae) published in 1959 by US astronomer Stewart Sharpless. Sh2 is referred to the second and final catalog. Number 276 refers to a H II object, in this case Bernard's Loop.
The image below shows Sh2-276 and Sh2-264, Lambda Orionis Ring or Angelfish Nebula.

Setting: 

Nikkor 24-200mm with ASI2600MC and H-Alpha filter

Exposure: 29x120, 19x180, 4x300 or  total integration time of 2h15min

Software: SharpCap, APP, DeNoise AI, CS4

13 Years Blogging

My blog started on December 23, 2012 ... already 13 years blogging :)

Astronomical Highlights 2025

Looking back on 2025, It was a difficult year for my health, and the weather didn’t always help either. But still there were a lot of unique and WOW  astronomical moments. Below my personal list

1) Attending Space Weather training at STCE

2) Aurora during our holliday in Iceland

3) My new Sol'Ex by James R with 2nd Gen slit, capturing E Corona & JASON2025

4) Red rainbow with more then 4700 likes, 245 remarks and 52 times shared

5) My first long exposure of 7h capturing M51

6) M31 with asteroid Eros and learning ASTAP

7) Sunspot AR4048

8) Interstellar Comet 3I/Altas

9) Planet Jupiter, Mars and Saturn

10) Comet C/2025 A6

11) Wide field of Mercury, Venus, Jupiter and the Moon

Sol'Ex JSolEx 4.4 3D

JSolex version 4.4 creates a 3D image of the Sun using an image made with Sol'Ex.

SOLAP Sol'Ex

Nice feedback from SOLAP project: 

I wanted to thank you because this is the first year since the SOLAP
collaboration that we will have at least one shot per day in Ha in
BASS2000. We're not quite at 100% for CaH and CaK, but it's much better too.

Even even if we didn't have that feeling, 2025 was a good year in terms
of sunshine in Meudon. You have to go back to 2011 to find a better year.

I am taking a few days off, but you can still submit your photos during
this period. I will process them when I return on 31 December.

I wish you all a very happy holiday season.

Florence

Adjusting GEN2 slit Sol'Ex

Summary of  NOTICE projet Sol’Ex Le réglage fin du système collimateur Christian Buil

Adjusting a spectroheliograph is less straightforward than it may seem at first, because the camera focus and the light collimation influence each other. A spectrum can look sharp while astigmatism is still present — a tricky optical error where the image is sharp in one direction but not in the perpendicular one. For that reason, a step-by-step, iterative adjustment is required, alternately refining the camera focus and the collimator setting.

To make astigmatism clearly visible, a simple yet clever solution is used: an artificial field edge. By covering roughly half of the slit with a very thin piece of aluminium foil, a sharp transition is created. This makes it possible to judge the sharpness of both the spectral lines and the edge at the same time. Repeating this process a few times leads to an optimal and permanent adjustment — and that directly translates into better solar images.

With the GEN2 slit, an additional challenge appears. At 6 mm, this slit is relatively long, while the Sol’Ex optics were originally designed for a shorter slit. Toward the ends of the GEN2 slit, other optical aberrations become significant and can make focusing misleading. This is exactly where the aluminium-foil method proves its value: by using only the central, optically most reliable part of the slit, these disturbing effects are greatly reduced, allowing accurate collimation.

With the GEN1 slit, the slit itself is shorter and edge-related issues are less pronounced, but there is a different limitation: the chrome-coated surface of the slit is not accessible. As a result, the aluminium-foil mask cannot be applied, and this practical method for reliably checking and correcting astigmatism cannot be used.