7 x narrowband for M42

[riklaunim]

Here is my first full multi-narrowband comparison that includes helium, argon and neutral oxygen exotic bands. To shoot Ha/S2/O3 I used Baader narrowband filters, and for exotic bands - Edmund Optics filters... plus Baader Solar Continuum to get continuum image (reflective parts of the nebula). Solar Continuum doesn't catch any emission bands (except maybe weak 543 nm helium band) so it will show only reflective parts.

In general helium should be visible close to stars that excite the gas (as it needs a lot of energy to glow). "Neutral" oxygen, [O I] will glow where there isn't enough energy to excite the gas (like H-alpha or [O III]). In planetary nebulae filaments/gas condensations may glow in [O I], while in nebulas like M42/43 it's rather hard to say what and where it will glow (if at all). [Ar III] is yet another band (and I can't say if it's somewhat specific compared to those more popular).

Processed single mono images, and raw stacks are available in my gallery: part I, part II, part III and part IV

The comparison:

[s II] vs Continuum; clear difference visible (red is sulphur):

[Ar III] vs Continuum; slight difference only:

[O I] vs Continuum; not much difference. Not much [O I] in M42/43:

[Ar III], [s II], He I:

Helium makes trapezium pink

[s II] - H-alpha, [O III], [s II]:

In this case "exotic" bands didn't add much (maybe except helium). Crab nebula should show bigger differentiation. Cone and Rosetta nebula will also be checked

You may also check M42 spectrogram: http://astrosurf.com/buil/lhires3_faint/poster.png

[steppenwolf]

Fascinating stuff, thanks for sharing.

[Catanonia]

ok a lot of that went over my head but fascinating.

To sum up, are the filters worth it in your opinion ?

[riklaunim]

[O I] looks most interesting, and helium maybe second - for some planetary nebulas. As for H II region nebuls - that needs to be checked

[ollypenrice]

Well done for trying somethng new and exciting.

Olly

[philj]

Fascinating stuff shows there is some useful work that can be done.

Philj