Closed vnp85 closed 1 month ago
I don't think that copying INTI's polynomial values will help, because they can be "reversed" (the polynomial makes sense based on the orientation, which may be different). However I think I understand what's going on. I will keep you posted.
Thank you.
Some polar caps are visible also in hydrogen, let me post it.
For the Ca from above, I tried to black box test with each scenario:
I also tried to exclude the possibility of instrument error and/or artefacts, hence also processing with INTI.
And a sanity check against the Sun, just in case (Vega would most certainly show polar caps).
Beta
Alpha
To be clear there are 2 separate issues at play here:
Hm, I read about you adding a flat correction only tangentially, I didn't think much of it as a possible source of problems.
My Sol'Ex setup may be somewhat atypical in that instead of a ND filter I've seen most people use, I have a piglet setup: I use full aperture narrow band filters as ERFs, in a filter drawer in front of the lens, which gives it a snout shape, hence the name. This limits my aperture to 2", but keeping all the light I need, hence even 360 fps is a possibility, with zero gain. And throwing out the rest with at least OD2 or even OD5, depending on the filter quality. I have some Chinese cheapo Na filter that's around OD2-3, but Antlia's Ca-Ha triband ERF is supposed to be good enough. These filters may lead to odd reflections (which I clearly have), on top of the slit's possible unevenness manifesting itself in low contrast situations, such as the Helium line.
Thank you @melix , I downloaded the 2.6.3 dev version and it indeed performs better.
Detailed tests with version 2.6.2 dev, issue first observed with 2.6.1 dev.
Context: in Calcium H/K, line detection may fail becasue of the unusually high activity of the Sun, turning a dark absorption line into an emission line, at least regionally -- but those regions are substantial. When line detection fails, as of version 2.6.1 dev, one can try either manually putting markers and thus obtain a polynomial, or choose a happy frame's polynomial to be used globally.
The problem: with both forced polynomials, the image shows unexpected banding and wavelength deviations (often times as "polar caps") no matter the settings.
INTI: running the same ser video (link below) also tested with INTI, which does manage to find right wavelength, and produces the expected image with only minor glitches. Most importantly: no large scale banding and no polar caps.
JSol'Ex: taking the coefficients from INTI, and pasting the crafted JSON into the input field, still fails to produce the expected image.
The ser video: http://narnia.go.ro/seagate2tb.php?mask=2024-07-14
For context, image results with different settings. For reference, an etalon image I took the day before (Lunt):
INTI's output, full auto:![image](https://github.com/user-attachments/assets/975eb026-eebf-4661-8c4b-43202fa9e158)
JSol'Ex 2.6.2 dev, full automatic, disk_0_00 png![image](https://github.com/user-attachments/assets/2e34f533-6a1e-4f98-aa19-3b8f5d57f15a)
JSol'Ex 2.6.2 dev, forced polynomial from happy line, disk_0_00 png![image](https://github.com/user-attachments/assets/7f01c37a-810f-46ce-965b-741e0619beb6)
JSol'Ex 2.6.2 dev, forced polynomial from manually placed markers, increasing markers density towards the disk edge to force the curve accuracy, disk_0_00 png![image](https://github.com/user-attachments/assets/eddc01e8-8445-4d17-8370-29cc88252b53)
JSol'Ex 2.6.2 dev, coefficients taken from inti, the cubic one (missing from INTI) set to zero, disk_0_00 png![image](https://github.com/user-attachments/assets/e90ad559-90e8-40cb-8a4d-c875ee162aab)