My Helios collegue, Walter, informed me about a new imaging software SHG_Main for spectroheliographic images of the Sun. My files from October 14, 2023, which included Sodium D1, D2 and Helium (D3) could not be processed using INTI software. So after installing SHG_Main I succesfully processed the data and after editing I got a solardisk in Helium D3. My first one even!
The software has a "spectrum" tab which searches for different lines. In my case I anchored Na (D1) and Na (D2) and after calculation of the dispersion factor the software found the He D3 line (see graph).
An Helium D3 image was made using the data from the spectrum tab and another image was made with -10 pixels further away from He D3 line. Both pictures were substracted from each other using CS4 and false colours were added.
I do remember that the data set was made under windy conditions which prevented a smooth recording that day.
Comparison between solar pictures in H-Alpha, CaK and He D3. All pictures taken on October 14,2023. All three pictures show prominences.