I’ve been experimenting with unusual narrowband filters. In this pic BLUE= iron and methylide emission lines (aka the G band) , Green = Mg and Orange= Sodium. I wasn’t sure what to expect but it turns out to be most interesting. A bit like an onion there seems to be layers. The green magnesium hangs out near the core. In the next layer the Sodium and around the edge (and also a bit in the middle too) the iron and/or methylide. It turns out that methylidyne (CH) is very common in space. In 1937 methylidyne’s strong 430nm emission wavelength was detected and by the 1940’s methylidyne was confirmed as the first molecule known to be present in interstellar space. Apparently it’s an important and basic ingredient for life (life as we know it Jim). Obviously it’s not going to be as common in space as hydrogen or helium or many of the other elements and yet it seems to have been picked up quite strongly in this little test. Or at least methylidyne and/or iron (because the G band filter encompasses both emission lines) seems to have been picked up quite strongly. So I’m thinking this G-Band emission line might be good for other nebula too. In fact it makes me wonder why us amateurs haven’t been narrowband imaging with it already. I mean Sulphur is very weak and I suspect we’re only imaging in that wavelength bc hubble is. If methylidyne is on par or even stronger than Sulphur then it could really add something to the amateur’s arsenal. Also as methylidyne is firmly blue we wouldn’t have to do the big botch known as the hubble pallete to make our space pics look nice. But Nico from Nebula Photos pointed out in the patron chat that the G-band filter’s passband is wide enough to register general blue light rather than specifically the light emitted from the methylidyne. And this is a good point. Maybe I’m just picking up the blue light from this very bright nebula? Next time I’ll reconfigure my filter wheel and take the same shot with the same scope with just a blue filter and compared the two. Thing is flipping the argument around it may be that a significant amount of the blue light we see in space comes from methylidyne (and/or Iron) anyway. Hmmmn…
I used the wow scope for this little adventure placed on the Skywatcher CQ350 which I’m testing out – thx Andrew for lending this mount to me. This is a big mount for such a medium sized scope but my mum’s back garden in Devon was pretty windy that night and so anything less would have cause an unduly large amount of wobble
Just from this little experiment into weird narrow band filters I think more investigation is worthwhile. It looks to me like the “eye” of Orion through the G band filter is brighter than through a regular blue filter. So I’m hopeful we are picking up something other than regular blue light. I suspect I’ve gone past my paygrade with this discussion though. If you are knowledgeable in such areas have anything to add please write a comment below.
BTW the 2nm Magnesium filter seems quite weak. It’s concentrated around the core. The 2nm sodium filter has potential. Its noticeably weaker in the “eye” of orion than the Ha band. Annoyingly the sodium emission line is what is used in sodium night lights so it might not be a good choice for light polluted sights. That being said London is now almost entirely LED now so I might give it shot.
Hello astrobiscuit.com owner, Your posts are always well-received and appreciated.
I have a slit spectrograph, and (when the weather improves – am in NZ) will try to make observations of a number of “slices” through the nebula, with corresponding images from the guide camera so you can see where the slit has been positioned.
Big professional observatories sometimes have instruments which can slice the image up to send it to spectrographs in slices (this is also done in some cases with microlens/pinhole arrays, or optic fiber arrays) and output the results as a 3d “datacube” for later analysis of the spectral distribution across the focal plane.
the spectra I can take range from circa 420nm through to 840nm.
then you would be able to see what’s narrow emission line light and what’s perhaps continuum light reflecting off dust, to aid in selection of appropriate narrowband filters.
Have taken data for three slices through M42 last night, will process and forward to Rory.
I would like to see this, too!