I semi-inverted (ballistic gamma curve) the Helium image, to get this view where the coronal hole’s „reflection”, in reality some excess light, gets to look dark.
Some more Helium games, 2025-03-05
The Helium Sun on 2025-02-09
With the usual setup, from the Ersatz-Obsi, I imaged the Sun in He I D3. A stack of 96 spectroheliograms (scans).
Again, the coronal hole, as a large scale feature, is readily visible.
Processing scripts are here.
2025-02-09, the Sun in He I D3, enhanced signal
colorized
comparison with the SDO/AIA image
A great spiral on the Sun, 2025-03-01
Cloudy and hazy sky, but hey, what else to do. The He I D3 enhanced signal clearly reflects what the corona is doing, according to NASA/SDO/AIA
https://sdo.gsfc.nasa.gov/assets/img/browse/2025/03/01/20250301_100911_1024_0211.jpg
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The Helium Sun on 2025-02-27
Finally, not just decent transparency (but awful turbulence), but also decent seeing. Helium I D3.
Solar Autoguider for my SHG
I took an ESP32 board, with a camera and LCD, and turned it into an autoguiding component for my spectroheliograph setup. Below’s the source code — before you judge it, think about it as an as-is release, half of it written while recording the Sun itself, mostly for fun. Some day in the future I may clean it up. PS: form9 from the printscreen got a decent title.
Note that, for this particular setup featured here:
- the ESP32 / OV2640 / ST7789 development board in the picture doesn’t have remaining free pins (maybe if the SPI/I2C buses are tapped into). My solution reports the center of gravity through the serial port.
- the EQ3 hand controller originally doesn’t have an ST4 connector
Both limitations from above have been overcome in my particular setup: I rebuilt the EQ3’s controller from the ground up, only the stepper motors are from factory, and it includes a special spectroheliograph scan mode. Both the autoguider and the otherwise standalone embedded device EQ3 controller connect to a desktop app, to the The Soapbox MountPusher Guider assembly. Thus the control is centralized there and Sharpcap, camera cooling, autoguiding etc are all orchestrated in a concert. See the family portrait below.
Some quick photos
2025-02-2x–vnp-esp32cam-solar-autoguider-7
2025-02-2x–vnp-esp32cam-solar-autoguider-4
2025-02-2x–vnp-esp32cam-solar-autoguider-6
2025-02-2x–vnp-esp32cam-solar-autoguider-5
2025-02-2x–vnp-esp32cam-solar-autoguider-2
2025-02-2x–vnp-esp32cam-solar-autoguider-3
2025-02-2x–vnp-esp32cam-solar-autoguider-1
2025.03.13. 100831
2025-01-25 Bad Ha Sky, Manual Culling
Borges, the blind librarian, helping out to manually cull the results, and select which frames, if any, go to stacking. The fog/haze helped, but the clouds… didn’t.
2025-01-25-0805 2-Sun-Ha 2025.01.25. disk 0 00 pipp lapl2 ap12291 reg1 ps4 mono
2025-01-25-0805 2-Sun-Ha 2025.01.25. disk 0 00 pipp lapl2 ap12291 reg1 ps4 color
manual culling
All the way to the corona
On 2025-01-12, I imaged the Sun in He I D3. Using my scripts to extract the weak signal, I got able to show features otherwise characteristic of the corona. I stacked a total of 72 scans, spanning between 2025-01-12-0741Z and 2025-01-12-0933Z. Basically, I imaged the fingerprint of the giant coronal hole.
Helium – don’t peek into secrets
The Helium I D3 line, unless one knows exactly what to look for, is elusive to put it mildly. Hence the secret. And the poet, Attila JÓZSEF warned us: a titkokat ne lesd meg. So let’s take the spectroheliograph and image the Sun ostinatamente. 78 scans went into this image on 2024-11-02.
The Helium Sun on 2024-11-07
Using the spectroheliograph and the ~30nm wide sodium ERF filter, I imaged the Sun in the He I D3 spectral line. Recordings processed with JSol’Ex, and details enhanced by the script below. For the final images, about forty individual frames (reconstructed scans) were stacked.
Fun fact, the light triangle in the lower half of the image corresponds to a dark feature in the corona, as seen on the SDO AIA 211 image.
