[Solved] automatic filter assignment

I'll pass your request to Mabula, Thanks

Dear Sven @svenhallmann,

I think that there is a misconception here one way or the other.

First, regarding filters for Hydrogen, a HII filter simply does not exist to my knowledge because there is not such an emission line. For the hydrogen atom we have, for instance the Balmer emission lines that include H-alpha and H-beta:

https://en.wikipedia.org/wiki/Balmer_series

But there is much more actually for hydrogen, the famous H-alpha line is actually not part of the first Hydrogen series wich is the Lyman series...:

https://en.wikipedia.org/wiki/Hydrogen_spectral_series

H-alpha is very famous because it is emitted a lot in the universe, but it is not famous for being the most simple hydrogen emission line I think. The specific H-alpha wavelength is directly related to the energy step where the electron surrounding the proton falls back from n=3 to n=2 with n=1 the lowest energy level of the electron and n=2 the second lowest energy level. So H-alpha emission does not occur due to a H-alpha atom being ionized and then becoming not-ionized. The electron is in an excited state (because the gas is hot) and releases energy by emitting a photon but it stays excited still...

Now we do have HII - Hydrogen II nebula, but this only means that these are nebula where Hydrogen is mostly ionized meaning most H-alpha atoms do not have an electron attached and thus most of those H atoms do not emit H-alpha nor H-beta. Only the non-ionized atoms in such a nebula will emit radiation like H-alpha or H-Beta:

https://en.wikipedia.org/wiki/H_II_region

So HII assignment is not related directly to either the H-alpha or H-Beta emission lines thus filters that we use in astronomy. A HII nebula will probably emit on both H-alpha and H-Beta and other H lines. The orion nebula is a HII region which is very bright in H-alpha and also in H-beta I think.

A HI nebula would ne a nebula with mostly neutral hydrogen atoms.

So my guess here is that you need to tell Nina that you shot with a H-alpha or a H-Beta filter instead of a H-II filter becaus a HII filter does not exist... Or does nina let you select a HII filter when you are composing your imaging session?

Mabula

@mabula-admin 

Thank you for the detailed and interesting explanation!

In fact, there was a misunderstanding on my part. I previously thought HII and H-Alpha were the same thing, just the 656.28 nm line.

In Nina I specify the name for the filters myself, which are then written into the Fits header. I have now corrected that and the automatic assignment works perfectly.

Hi Sven @svenhallmann,

Aaah, okay, no problem, glad it is solved 😉

Mabula