It was almost unusually calm up there, so decent atmospheric seeing. 65 scans entered this stack: a spectroheliogram of the Sun with enhanced He I D3 details. Also, it has become fairly trivial to see the coronal features’ being reflected in the helium image, the holes at 9 o’clock and 2 o’clock, showing up as excess light in Helium, are rather obvious.
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.
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
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
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.
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.
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.
The Sun on 2024-09-13, around the CaH line, also touching Hydrogen epsilon. Pixel shifts range from -36 pixels (blue wing) to +40 pixels (red wing), meaning somewhere around -2..+2 Å in total, give or take.
I combined some spectroheliograph data with the etalon, Sol’Ex at 62/400 with Lunt CaK B1800 at 102/1100.
